Category Archives: Invertebrates

Cicadas, or how I Am Such A Scientist, or a demonstration of good editing

Charles Q. Choi runs a bi-weekly series on the Guest Blog over at Scienctific American – Too Hard for Science? In these posts, he asks scientists about experiments that cannot be or should not be done, for a variety of reasons, though it would be fun and informative it such experiments could get done.

For one of his posts, he interviewed me. What I came up with, inspired by the emergence of periodic cicadas in my neighborhood, was a traditional circadian experiment applied to a much longer cycle of 13 or 17 years.

Fortunetaly for me, Charles is a good editor. He took my long rant and turned it into a really nice blog post. Read his elegant version here – Too Hard for Science? Bora Zivkovic–Centuries to Solve the Secrets of Cicadas.

Now compare that to the original text I sent him, posted right here:

The scientist: Bora Zivkovic, Blog Editor at Scientific American and a chronobiologist.

The idea: Everything in living organisms cycles. Some processes repeat in miliseconds, others in seconds, minutes or hours, yet others in days, months or years. Biological cycles that are most studied and best understood by science are those that repeat approximately once a day – circadian rhythms.

One of the reasons why daily rhythms are best understood is that pioneers of the field came up with a metaphor of the ‘biological clock‘ which, in turn, prompted them to adapt oscillator theory (the stuff you learned in school about the pendulum) from physics to biology.

And while the clock metaphor sometimes breaks down, it has been a surprisingly useful and powerful idea in this line of research. Circadian researchers came up with all sorts of experimental protocols to study how daily rhythms get entrained (synchronized) to the environmental cycles (usually light-dark cycles of day and night), and how organisms use their internal clocks to measure other relevant environmental parameters, especially the changes in daylength (photoperiod) – information they use to precisely measure the time of year and thus migrate, molt or mate during an appropriate season.

These kinds of experiments – for example building Phase-Response Curves to a variety of environmental cues, or a variety of tests for photoperiodism (night-break protocol, skeleton photoperiods, resonance cycles, T-cycles, Nanda-Hamner protocol etc.) – take a long time to perform.

Each data point requires several weeks: measuring period and phase of the oscillation before and after the pulse (or a series of pulses) of an environmental cue in order to see how application of that cue at a particular phase of the cycle affects the biological rhythm (or the outcome of measuring daylength, e.g., reproductive response). It requires many data points, gathered from many individual organisms.

And all along the organisms need to be kept in constant conditions: not even the slightest fluctuations in light (usually constant darkness), temperature, air pressure, etc. are allowed.

It is not surprising that these kinds of experiments, though sometimes applied to shorter cycles (e.g., miliseconds-long brain cycles), are rarely applied to biological rhythms that are longer than a day, e.g., rhythms that evolved as adaptations to tidal, lunar and annual environmental cycles. It would take longer to do than a usual, five-year period of a grant, and some experiments may last an entire researcher’s career. Which is one of the reasons we know so little about these biological rhythms.

~~~~~~

Living out in the country, in the South, just outside Chapel Hill, NC, every day I open the door I hear the deafening and ominous-sounding noise (often described as “horror movie soundtrack) coming from the woods surrounding the neighborhood. The cicadas have emerged! The 13-year periodic cicadas, that is. Brood XIX.

I was not paying attention ahead of time, so I did not know they were slated to appear this year in my neck of the woods. One morning last week, I saw a cicada on the back porch and noticed red eyes! A rule of thumb that is easy to remember: green eyes = annual cicadas, red eyes = periodic cicadas. I got excited! I was waiting for this all my life!

Fortunately, once they emerge, cicadas are out for a few weeks, so my busy travel schedule did not prevent me from going to find them (just follow the sound) to take a few pictures and short videos.

There are three species of periodic cicadas that emerge every 17 years – Magicicada septendecim, Magicicada cassini and Magicicada septendecula. Each of these species has a ‘sister species’ that emerges every 13 years: M.tredecim, M. tredecassini and M.tredecula. A newer species split produced another 13-year species: Magicicada neotredecim. The species differ in morphology and color, while the 13 and 17-year pairs of sister species are essentially indistinguishable from each other. M.tredecim and M.neotredecim, since they appear at the same time and place, differ in the pitch of their songs: M.neotredecim sings a higher tone.

So, how do they count to 13 or 17?

While under ground, they undergo metamorphosis four times and thus go through five larval instars. The 13 and 17-year cicadas only differ in the duration of the fifth instar. They emerge simultaneously, live as adults for a few weeks, climb up the trees, sing, mate, lay eggs and die.

When the eggs hatch, the newly emerged larvae fall from the trees to the ground, dig themselves deeper down, latch onto the tree roots to feed on the sap, and wait another 13 or 17 years to emerge again.

There are a number of hypotheses (and speculations) why periodic cicadas emerge every 13 or 17 years, including some that home in on the fact that these two numbers are prime numbers (pdf).

Perhaps that is a way to fool predators which cannot evolve the same periodicity (but predators are there anyway, and will gladly gorge on these defenseless insects when they appear, whenever that is, even though it may not be so good for them). Perhaps this is a speciation mechanism, lowering the risk of hybridization between recently split sister species?

Or perhaps that is all just crude adaptationist thinking and the strangeness of the prime-number cycles is in the eye of the beholder – the humans! After all, if an insect shows up every year, it is not very exciting. Numerous species of annual cicadas do that every year and it seems to be a perfectly adaptive strategy for them. But if an insect, especially one that is so large, noisy and numerous, shows up very rarely, this is an event that will get your attention.

Perhaps our fascination with them is due to their geographic distribution. Annual cicadas may also have very long developmental times, but all of their broods are in one place, thus the insects show up every year. In periodic cicadas, different broods appear in different parts of the country, which makes their appearance rare and unusual in each geographic spot.

In any case, I am more interested in the precision of their timing than in potential adaptive explanations for it. How do they get to be so exact? Is this just a by-product of their developmental biology? Is 13 or 17 years just a simple addition of the duration of five larval stages?

Or should we consider this cycle to be an output of a “clock” (or “calendar”) of sorts? Or perhaps a result of interactions between two or more biological timepieces, similarly to photoperiodism? In which case, we should use the experimental protocols from circadian research and apply them to cicada cycles.

Finally, it is possible that a ling developmental cycle is driven by one timing mechanism, but the synchronization of emergence in the last year is driven by another, perhaps some kind of clock that may be sensitive to sound made by other insects of the same species as they start digging their way up to the surface.
The problem: In order to apply the standard experiments (like construction of a Phase-Response Curve, or T-cycles), we need to bring the cicadas into the lab. And that is really difficult to do. Husbandry has been a big problem for research on these insect, which is why almost all of it was done out in the field.

When kept in the lab, the only way to feed them is to provide them with the trees so they can drink the sap from the roots. This makes it impossible to keep them in constant conditions – trees require light and will have their own rhythms that the cicadas can potentially pick up, as timing cues, from the sap. So, the first thing we need to do is figure out a way to feed them artificially, without reliance on living trees for food.

Also, we do not know which environmental cues are relevant. Is it light cycle? Photoperiod? Or something cycling in the tree-sap? Or temperature cycles? What are the roles of developmental hormones like Juvenile Hormone or Ecdysone? We would have to test all of them simultaneously, hoping that at least one of them turns out to be the correct one.

Second, more obvious problem, is time. These experiments would last hundreds of years, perhaps thousands! Some experiments rely on outcomes of previous experiments for the proper design. Who would do them? What funding agency would finance them? Why would anyone start such experiments while knowing full well that the results would not be known within one’s lifetime? Isn’t this too tantalizing for a scientist’s curiosity?

The solution? One obvious solution is to figure out ways to get to the same answers in shorter time-frames. Perhaps by sequencing the genome and figuring out what each gene does (perhaps by looking at equivalents in other species, like fruitflies, or inserting them into Drosophila and observing their effects), hoping to find out the way timing is regulated. This will probably not answer all our questions, but may be good enough.

Another way is to set aside space and funding for such experiments and place them into an unusual administrative framework – a longitudinal study guided by an organization, not a single researcher getting a grant to do this in his or her lab. This way the work will probably get done, and the papers will get published somewhere around 2835 A.D.

~~~~

See? How long and complex my text is? Now go back to the post by Charles to see again how nicely he edited the story.

Cicadas, Brood XIX, northern Chatham Co, NC [Videos]



Guest Blog at Scientific American – second guest post: We all need (a little bit of) sex

As I noted yesterday, the Scientific American Guest Blog is about to get really busy! Already today we have another new post – We all need (a little bit of) sex by Lucas Brouwers (blog, Twitter). Go and check it out and post comments (it takes a second to register).

Insects! Outreach and Three Books (video)

From Joanne Manaster:

Joanne shares information about the University of Illinois’ outreach, BugScope and tells of a yearly event featuring insects called The Insect Fear Film Festival. Awesome! Also, three Featured Books by Sonia Dourlot (Insect Museum), Hugh Raffles (Insectopedia) and May Berenbaum (The Earwig’s Tale) All three books have chapters listed in alphabetical order, but not in the way you would imagine

Look Up! The Billion-Bug Highway You Can’t See (video)

Bed bugs and cockroaches: The insects that bug us

Our August Science Café (description below) will be held on Tuesday 8/17 at Tir Na Nog on S. Blount Street.

Just in time to lead up to BugFest the museum’s annual event highlighting the world of arthropods, our café this month will be a discussion about insects (in particular, some species that we are not too fond of… bed bugs and cockroaches!)

I first learned about bed bugs from a television documentary probably a year or more ago. Since that show, and most likely because I work in a natural history museum, I have heard more and more about these pests and how difficult they are to deal with. Because travelers can bring them home in suitcases after staying in infested hotel rooms, it is important for all of us to understand their life history. An interesting website http://bedbugregistry.com/, is a site where the public report bed bugs that they have encountered in hotels and apartments. You can see from the listings that these pests are found throughout our country.

Another pest that people are more familiar with, the cockroach, (found in all 50 states) is also very difficult to deal with — So, we’ve added them to the line up for our evening’s café discussion. Learn how to distinguish one species of roach from another and how to be on the lookout for these unwanted house (or office) guests.

Bed bugs and cockroaches: The insects that bug us

Tuesday, August 17, 2010

6:30-8:30 p.m. with discussion beginning at 7:00 followed by Q&A

Tir Na Nog, 218 South Blount Street, Raleigh, 833-7795

After disappearing from many countries for almost 50 years, bed bugs have made a comeback and are once again sucking our blood while we sleep and stowing away in our luggage when we travel. Cockroaches, on the other hand, have always been a fact of life for people living in the South, but all roaches are not the same — some are part of our outdoor environment and only end up in our homes by accident, while others are only found in buildings and produce allergens that can pose health risks.

In this Science Café, we will explore some of the urban legends related to bed bugs, observe some insects to get an idea of what to watch out for, and discuss how you can keep these tiny vampires out of your home. We will also discuss do-it-yourself options for cockroach control as well as give you some cockroach identification tips.

About Our Speaker: Richard Santangelo is a research specialist in the Entomology Department at North Carolina State University. His work focuses on urban pest control aspects of entomology, including pesticide resistance monitoring of cockroaches and bed bugs, product testing of commercial insecticides for pest control, and allergen intervention in low income housing and hog farms. Santangelo has also worked on a Colorado Spider Survey with the Denver Museum of Nature and Science and biological control of cotton pests in Arizona.

Craig McClain talk at Sigma Xi

Although I’ve known Craig McClain for a few years now, both online and offline, I only had some vague ideas about what kind of research he is doing. I knew it has something to do with the Deep Sea and with the evolution of body size, but I did not know the details. So, when the opportunity arose to hear him give a talk summarizing his work, I jumped to it and went to see him on Tuesday at Sigma Xi as a part of their pizza lunch series.
Craig1.jpg
First I have to say that Craig is a great speaker (if you are looking for one for a seminar series, this is useful information for you) – it was fun and very clear. And thought-provoking. And fascinating. I am still thinking about it, what it all means, etc.
Craig2.jpg
But Delene was there as well and she took copious notes and wrote a great blog post about the talk so there is no need for me to duplicate that effort. So if you want to know more about the substance of the talk, just go and read her take either on her own blog Wild Muse or the same post on the ScienceInTheTriangle blog.
Craig3.jpg

What bug is this?

A reader sent me this picture, asking for an ID – it was taken in upstate New York:
NY bug.jpg

Breakfast with a side of Science – What’s Bugging You? Animals We Love to Hate

At the NC Museum of Natural Sciences:

What’s Bugging You? Animals We Love to Hate
Wednesday, September 30, 2009
8:00 – 10:00 am with discussion beginning at 9:00 followed by Q&A
Location: The Acro Cafe – 4th Floor of the Museum of Natural Sciences
Fire ants. Mosquitoes. Flies. Ticks. Gnats. Bed Bugs. The list goes on and on.
They disturb our sleep, sting us, envenomate us, suck our blood, eat our food, crawl on us…yet at the same time, they pollinate our food and flowers, provide insect control, and increase biodiversity. So, what is a pest? Are some of these pests invasive species? What can or should be done about them?
About the Speaker:
Join Dr.Colin Brammer, Entomologist and Curator of the Museum’s Naturalist Center for a discussion on all things pest related in our next Breakfast with a Side of Science

The Butterfly House on the island of Mainau

A couple of German bloggers and I went to see the Butterfly House on the Island of Mainau. They had good cameras with lenses that allowed them to take extreme close-ups. I had to do with a little pocket camera, but a few pictures turned out decent enough to show:

Continue reading

Name this Bug!

I am pretty sure it’s a true bug (i.e., I am not being sloppy by calling just any ole’ insect a bug). I got as close as I could with my iPhone, but the lighting was bad. This is on my porch and the bug is really large – about 1 inch in length of the body.
bug1.jpg
bug2.jpg
bug3.jpg
bug4.jpg
bug5.jpg
So, what is it?

Why social insects do not suffer from ill effects of rotating and night shift work?

ResearchBlogging.orgMost people are aware that social insects, like honeybees, have three “sexes”: queens, drones and workers.
Drones are males. Their only job is to fly out and mate with the queen after which they drop dead.
Female larvae fed ‘royal jelly’ emerge as queens. After mating, the young queen takes a bunch of workers with her and sets up a new colony. She lives much longer than other bees and spends her life laying gazillions of eggs continuously around the clock, while being fed by workers.
Female larvae not fed the ‘royal jelly’ emerge as workers.
Workers perform a variety of jobs in the hive. Some are hive-cleaners, some are ‘nurses’ (they feed the larvae), some are queen’s chaperones (they feed the queen), some are guards (they defend the hive and attack potential enemies) and some are foragers (they collect nectar and pollen from flowers and bring it back to the hive).
What most people are not aware of, though, is that there is a regular progression of ‘jobs’ that each worker bee goes through. The workers rotate through the jobs in an orderly fashion. They all start out doing generalized jobs, e.g., cleaning the hive. Then they move up to doing a more specialized job, for instance being a nurse or taking care of the queen. Later, they become guards, and in the end, when they are older, they become foragers – the terminal phase.
This pattern of behavioral development is called “age polyethism” (poly = many, ethism = expression of behavior), or sometimes “temporal polyethism” (image from BeeSpotter):
Age polyethism.jpg
This developmental progression in behavior is accompanied by changes in brain structure, patterns of neurotransmitter and hormone synthesis and secretion, and patterns of gene expression in the central nervous system.
Some years ago (as in “more than ten years ago”) Gene Robinson and his students started looking at daily patterns of activity in honeybees. The workers in their early stages are doing jobs inside the hive, where it is always dark. They clean the hive, take care of the eggs and pupae, and feed the larvae and the queen around the clock. Each individual bee sometimes works and sometimes sleeps, without any semblance of a 24-hour pattern. Different individuals work and sleep at different, apparently random times. The hive as a whole is thus constantly busy – there is always a large subset of workers performing their duties, day and night.
As they get older, they start doing the jobs, like being guards, that expose them to the outside of the hive, thus to the light-dark and temperature cycles of the outside world.
Finally, the foragers only go out during the daytime and have clear and distinct daily rhythms. Furthermore, the foragers have to consult an internal clock in order to orient towards the Sun in their travels, as well as to be able to communicate the distance and location of flowers to their mates in the hive using the ‘waggle dance’. As bees are social insects, it is difficult to keep individuals in isolation for longer periods of time, but it has been done successfully and, in such studies, foragers exhibit both freerunning (in constant darkness) and entrained (in light-dark cycles) circadian rhythms, while younger workers do not.
In the Robinson lab, then PhD student Dan Toma and postdoc Guy Bloch did much of the early and exciting work on figuring out how the rhythmicity develops in individual worker bees as they pass through the procession of ‘jobs’.
In an early study, they measured levels of expression of mRNA of the core clock gene Period (Per). The gene was expressed at low levels and no visible daily rhythm in early-stage workers, but at much higher levels and in a circadian fashion in foragers.
As the levels of expression were measured crudely – in entire bee brains – it was impossible at the time to be sure which of the two potential mechanisms were operating: 1) the celluular clock did not work until the bee became a forager, or 2) the cellular clocks were working, but different cells were not synchronized with each other, producing a collectively arrhythmic output: both as measured by gene expression of the entire brain and as measured by behavior of the live bee.
Either way, the study showed correlation: the appearance of the functional circadian clock coincided with other changes in the brain structure, brain chemistry and bee behavior. They could not say at the time what causes what, or even if the syncronicity of changes was purely coincidental. They needed to go beyond correlation and for that they needed to experimentally change the timing to see if various processes can be dissociated or if they are tightly bound to each other.
And there is a clever way to do this! First, they took some hives and removed all the foragers from it. This disrupted the harmony of the division of labor in the hive – too many cleaners and nurses, but nobody is bring the food home. When that happens, the behavioral development of other workers speeds up dramatically – in no time, some nurses and guards develop into foragers. And, lo and behold, the moment they became foragers, they developed rhythms in behavior and rhythms of the Per gene expression in the brain. So, as the development is accelerated, everything about it is accelerated at the same rate: gene expression, brain structure, neurochemistry, and behavioral rhythmicity.
Nice, but then they did something even better. They removed most of the cleaners and nurses from some hives. Again, the balance of the division of labor was disrupted – plenty of food is arriving into the hive but there is not enough bees inside to take care of that food, process it, feed the larvae, etc. What happened then? Well, some of the foragers went back into the hive and started performing the house-keeping duties instead of flying out and about. And, interestingly, their brain structure and chemistry reverted its development to resemble that of cleaners and nurses. They lost behavioral rhythmicity and started working randomly around the clock. And the rhythm of clock-gene expression disappeared as well.
So, genetic, neural, endocrine, circadian and behavioral changes all go together at all times. Social structure of the colony, through the patterns of pheromones present in the hive, affects the gene expression, brain development and function, and behavior of individual bees. Just like the gene expression and behavioral patterns, the patterns of melatonin synthesis and secretion in honeybee brains is low and arrhythmic in young workers and becomes greater and rhythmic in foragers. With the recent sequencing of the honeybee genome, the potential for future research in honeybee chronobiology looks promising and exciting.
But are these findings generalizable or are they specific to honeybees? How about other species of bees or other social insects, like wasps, ants and termites? Are they the same?
Other species of socials insects have been studied in terms of age polyethism as well. The earliest study I am aware of (let me know if there is an older one) studying behavioral rhytmicity in relation to behavioral development was a 2004 Naturwissenschaften paper by Sharma et al. on harvester ants. In that study, different castes of worker ants exhibited different patterns – some were strongly diurnal, some nocturnal, some had strange shifts in period, and some were arrhythmic. Those with rhythms could entrain to light-dark cycles as well as display freerunning rhythms in constant darkness.
Just last month, a new paper on harvester ants came out in BMC Ecology (Open Access). In it, Ingram et al. show that foragers have circadian rhythms (both in constant darkness and entrained to LD cycles) in expression of Period gene (as well as behavioral rhythms), while ants working on tasks inside the hive do not exhibit any rhythms either in clock-gene expression or in behavior, suggesting that the connection between age polyethism and the development of the circadian clock may be a universal property of all social insects.
We know that in humans, night-shift and rotating-shift schedules are bad for health as the body is in the perpetual state of jet-lag: the numerous clocks in our bodies are not synchronized with each other. We have evolved to be diurnal animals, entrained to environmental light cycles and not traveling over many time zones within hours, or working around the clock. Social insects have evolved a different strategy to deal with the potentially ill effects of shift-work: switch off the clock entirely until one develops far enough that time-keeping becomes a requirement.
Yang, L., Qin, Y., Li, X., Song, D., & Qi, M. (2007). Brain melatonin content and polyethism in adult workers of Apis mellifera and Apis cerana (Hym., Apidae) Journal of Applied Entomology, 131 (9-10), 734-739 DOI: 10.1111/j.1439-0418.2007.01229.x
Sharma, V., Lone, S., Goel, A., & Chandrashekaran, M. (2004). Circadian consequences of social organization in the ant species Camponotus compressus Naturwissenschaften, 91 (8) DOI: 10.1007/s00114-004-0544-6
Ingram, K., Krummey, S., & LeRoux, M. (2009). Expression patterns of a circadian clock gene are associated with age-related polyethism in harvester ants, Pogonomyrmex occidentalis BMC Ecology, 9 (1) DOI: 10.1186/1472-6785-9-7

Yes!!! Circus of the Spineless is Alive Again!

Hop over to The Other 95% and dig into all the invertebrate bloggy goodness!

Circadian Rhythm of Aggression in Crayfish

ResearchBlogging.orgLong-time readers of this blog remember that, some years ago, I did a nifty little study on the Influence of Light Cycle on Dominance Status and Aggression in Crayfish. The department has moved to a new building, the crayfish lab is gone, I am out of science, so chances of following up on that study are very low. And what we did was too small even for a Least Publishable Unit, so, in order to have the scientific community aware of our results, I posted them (with agreement from my co-authors) on my blog. So, although I myself am unlikely to continue studying the relationship between the circadian system and the aggressive behavior in crayfish, I am hoping others will.
And a paper just came out on exactly this topic – Circadian Regulation of Agonistic Behavior in Groups of Parthenogenetic Marbled Crayfish, Procambarus sp. by Abud J. Farca Luna, Joaquin I. Hurtado-Zavala, Thomas Reischig and Ralf Heinrich from the Institute for Zoology, University of Gottingen, Germany:

Crustaceans have frequently been used to study the neuroethology of both agonistic behavior and circadian rhythms, but whether their highly stereotyped and quantifiable agonistic activity is controlled by circadian pacemakers has, so far, not been investigated. Isolated marbled crayfish (Procambarus spec.) displayed rhythmic locomotor activity under 12-h light:12-h darkness (LD12:12) and rhythmicity persisted after switching to constant darkness (DD) for 8 days, suggesting the presence of endogenous circadian pacemakers. Isogenetic females of parthenogenetic marbled crayfish displayed all behavioral elements known from agonistic interactions of previously studied decapod species including the formation of hierarchies. Groups of marbled crafish displayed high frequencies of agonistic encounters during the 1st hour of their cohabitation, but with the formation of hierarchies agonistic activities were subsequently reduced to low levels. Group agonistic activity was entrained to periods of exactly 24 h under LD12:12, and peaks of agonistic activity coincided with light-to-dark and dark-to-light transitions. After switching to DD, enhanced agonistic activity was dispersed over periods of 8-to 10-h duration that were centered around the times corresponding with light-to-dark transitions during the preceding 3 days in LD12:12. During 4 days under DD agonistic activity remained rhythmic with an average circadian period of 24.83 ± 1.22 h in all crayfish groups tested. Only the most dominant crayfish that participated in more than half of all agonistic encounters within the group revealed clear endogenous rhythmicity in their agonistic behavior, whereas subordinate individuals, depending on their social rank, initiated only between 19.4% and 0.03% of all encounters in constant darkness and displayed no statistically significant rhythmicity. The results indicate that both locomotion and agonistic social interactions are rhythmic behaviors of marbled crayfish that are controlled by light-entrained endogenous pacemakers.

I think the best way for me to explain what they did in this study is to do a head-to-head comparison between our study and their study – it is striking how the two are complementary! On one hand, there is no overlap in methods at all (so no instance of scooping for sure), yet on the other, both studies came up with similar results, thus strengthening each other’s findings. You may want to read my post for the introduction to the topic, as I explain there why studying aggression in crayfish is important and insightful, what was done to date, and what it all means, as well as the standard methodology in the field. So, let’s see how the two studies are similar and how the two differ:
1) We were sure we used the Procambarus clarkii species. They are probably not exactly sure what species they had, so they denoted it as Procambarus sp., noting in the Discussion that it was certainly NOT the Procambarus clarkii, which makes sense as our animals were wild-caught in the USA and theirs in Germany. As both studies got similar results, this indicates that this is not a single-species phenomenon, but can be generalizable at least to other crayfish, if not broader to other crustaceans, arhtropods or all invertebrates.
2) We used only males in our study. They used only females. In crayfish, both sexes fight. It is nice, thus, to note that other aspects of the behavior are similar between sexes.
3) We used the term ‘aggression’. They use the term ‘agonistic behavior’, which is scientese for ‘aggression’, invented to erase any hints of anthropomorphism. Not a bad strategy, generally, as assumed aggression in some other species has been later shown to be something else (e.g., homosexual behavior), but in crayfish it is most certainly aggression: they meet, they display, they fight, and if there is no place to escape, one often kills the other – there is no ‘loving’ going on there, for sure.
4) The sizes of animals were an order of magnitude different between the two studies. Their crayfish weighed around 1-2g while ours were 20-40g in body mass. This may be due to species differences, but is more likely due to age – they used juveniles while we used adults. Again, it is nice to see that results in different age groups are comparable.
5) We did not measure general locomotor activity of our animals in isolation. We, with proper caveats, used aggressive behavior of paired animals as a proxy for general locomotor activity, and were straightforward about it – we measured aggressive behavior alone in a highly un-natural setup. As Page and Larimer (1972) have done these studies before, we did not feel the need to replicate those with our animals.
The new study, however, did monitor gross locomotor activity of isolated crayfish. Their results, confirming what Page and Larimer found out, demonstrate once again that activity rhythms are a poor marker of the underlying circadian pacemaker (which is why Terry Page later focused on the rhythm of electrical activity of the eye, electroretinogram – ERR – in subsequent studies) in crayfish. Powerful statistics tease out rhythmicity in most individuals, but this is not a rhythm I would use if I wanted to do more complex studies, e.g., analysis of entrainment to exotic LD cycles or to build and interpret a Phase-Response Curve. Just look at their representative example (and you know this is their best):
crayfish image 1.JPG
You can barely make out the rhythm even in the light-dark cycle (white-gray portion of the actograph) and the rhythms in constant darkness (solid gray) are even less well defined – thus only statistical analysis (bottom) can discover rhythms in such records. The stats reveal a peak of activity in the early night and a smaller peak of activity at dawn, similarly to what Page and Larimer found in their study, and similar to what we saw during our experiments.
6) They used an arena of a much larger size than ours. We did it on purpose – we wanted to ‘force’ the animals to fight as much as possible by putting them in tight quarters where they cannot avoid each other, as we were interested in physiology and wanted it intensified so we could get clearly measurable (if exaggerated) results. Their study is, thus, more ecologically relevant, but one always has to deal with pros and cons in such decisions: more realistic vs. more powerful. They chose realism, we chose power. Together, the two approaches reinforce and complement each other.
7) As I explained in my old post – there are two methodological approaches in this line of research:

Two standard experimental practices are used in the study of aggression in crustaceans. In one, two or more individuals are placed together in an aquarium and left there for a long period of time (days to weeks). After the initial aggressive encounters, the social status of an individual can be deduced from its control of resources, like food, shelter and mates.
In the other paradigm, two individuals are allowed to fight for a brief period of time (less than an hour), after which they are isolated again and re-tested the next day at the same time of day.

They used the first method. We modified the second one (testing repeatedly, every 3 hours over 24 hours, instead of just once a day).
What they did was place 6 individuals in the aquarium, a couple of hours before lights-off, then monitor their aggressive behavior over several days. What they found, similar to us, is that the most intense fights resulting in a stable social hierarchy occur in the early portion of the night:
crayfish image 2.JPG
Once the social hierarchy is established on that first night, the levels of aggression drop significantly, and occasional bouts of fights happen at all times, with perhaps a slight increase at the times of light switches: both off and on. Released into constant darkness, the pattern continues, with the most dominant individual initiating aggressive encounters a little more often during light-transitions then between them. The other five animals had no remaining rhythm of agonistic behavior: they just responded to attacks by the Numero Uno when necessary.
In our study we tried to artificially elevate the levels of aggression by repeatedly re-isolating and re-meeting two animals at a time. And even with that protocol, we saw the most intense fights at early night, and most conclusive fights, i.e., those that resulted in stable social hierarchy, also occuring at early nights, while the activity at other time of the day or night were much lower.
8) The goals of two studies differed as well, i.e., we asked somewhat different questions.
Our study was designed to provide some background answers that would tell us if a particular hypothesis is worth testing: winning a fight elevates serotonin in the nervous system; elevated serotonin correlated with the hightened aggression in subsequent fights, more likely leading to subsequent victories; crayfish signal dominance status to each other via urine; melatonin is a metabolic product of serotonin; melatonin is produced only during the night with a very sharp and high peak at the beginning of the night; if there is more serotonin in the nervous system, there should be more melatonin in the urine; perhaps melatonin may be the signature molecule in the urine indicating social status.
In order to see if this line of thinking is worth pursuing, we needed to see, first, if the most aggressive bouts happen in the early night and if the most decisive fights (those that lead to stable hiararchy) happen in the early night. This is what we found, indicating that our hypothesis is worth testing in the future.
They asked a different set of questions:
Is there a circadian rhythm of locomotor activity? They found: Yes.
Is there a circadian rhythm of aggression? They found: Yes.
Do the patterns of general activity and aggressive activity correlate with each other? They found: Yes.
Does the aggression rhythm persist in constant darkness conditions? They found: Yes.
Do all individuals show circadian rhythm of aggression? They found: No. Only the most dominant individual does. The others just defend themselves when attacked.
Is there social entrainment in crayfish, i.e., do they entrain their rhythms to each other in constant conditions? They found: No. All of them just keep following their own inherent circadian periods and drift apart after a while.
Is there a pattern of temporal competitive exclusion, i.e., do submissive individuals shift their activity patterns so as not to have to meet The Badassest One? They found: No. All of them just keep following their own inherent circadian periods.
So, a nice study overall, the first publication I know of that attempts to connect the literature on circadian rhythms in crayfish to the literature on aggressive behavior in crayfish.
Except….

Continue reading

Bizarre Squid Sex (no video)

In National Geographic:

A new investigation into the tangled sex lives of deep-sea squid has uncovered a range of bizarre mating techniques. The cephalopods’ intimate encounters include cutting holes into their partners for sex, swapping genders, and deploying flesh-burrowing sperm. These and other previously unknown reproductive strategies were documented in a survey of ten squid species living worldwide at depths of between 984 and 3,937 feet (300 and 1,200 meters). Study leader Henk-Jan Hoving, a Ph.D. student at the University of Groningen in the Netherlands, examined squid caught during research voyages as well as preserved museum specimens.

Of course, you can find many more examples of Weird Cephalopod Sex on Pharyngula….

27 Best Deep-Sea Species, take two

The list is now final. Here are the top 13:
#13 Deep-sea corals
#12: Yeti Crab
#11 Venus’s Flower Basket
#10: Echinothuriid Sea Urchins
#9: Bathynomus, the GIANT ISOPOD!!!!
#8 Red Lure Jellyfish
#7 Predatory Tunicates
#6: Giant Sea Spiders
#5 Barreleye Fish
#4 Gold-Footed or Scaly Foot Snail
#3 Flesh Eating Sponges
#2: Bone-Devouring Zombie Worms from Hell
#1 Vampire Squid

Can you raise sea-water blue crabs in fresh-water ponds?

Apparently yes: Freshwater Farm Ponds Turning into Crab Farms:

North Carolina’s native blue crab population has been at historic lows since 2000. Dr. Dave Eggleston, director of NC State’s Center for Marine Sciences and Technology (CMAST) and professor of marine, earth and atmospheric sciences, looked at various methods for helping the population recover. He hit upon a solution which not only reduces pressure on existing crab populations, but also benefits farmers looking to diversify their crops: using irrigation ponds on farms to grow blue crabs.
—————————-
Eggleston and his fellow researchers discovered that crabs can tolerate a salinity level of only .3 parts per thousand, which is about the same level found in coastal tap water. They did further work to determine the best set of circumstances for raising crab: population density, food rations, and habitat structure in ponds.
This past July, Eggleston and Ray Harris, NC State director of cooperative extension for Carteret County, had the opportunity for a large-scale test when they stocked a 10-acre lake with 40,000 hatchery-raised crabs, and a smaller pond with 4,000 crabs. The crabs will take approximately 105 days to reach maturity, and so far the endeavor looks successful.
With the rapid rate of growth for pond-raised crabs, Eggleston expects that in a given year, a farm could produce two to three harvests, as crabs don’t do well in freshwater during the winter months.
“If you look at a 2 1/2 -acre pond, you could stock it with 50,000 hatchery-raised crabs and expect to harvest around 20 percent, or 10,000 fully grown crabs. At $3 per crab, that’s $30,000 – and multiply that times three. It definitely adds up.”

iNaturalist rocks!

iNaturalist%20logo.gif
Thanks Bill for drawing my attention to iNaturalist which has the makings of an awesome site!
What is it?
It is essentially a Google Map where people can add pins every time they see an interesting critter: a plant, fungus, animal, etc. What is recorded is geographical coordinates and time when it was posted.
Moreover, people can link from the pins to pictures of the sighted critters if they upload them on Flickr (nice way to interlink existing social networking sites instead of reinventing the wheel). And they can put additional information, e.g., description of the habitat where they saw the creature. They can try to identify it and others can chime in agreeing or disagreeing on the ID. One can also view maps in various ways – by time, by broader groups (e.g., insects, birds…), or by the degree of agreement people have about the ID.
The site has, apparently, just started, thus the number of people and the number of sightings is still relatively small and limited to mainly a couple of geographic locations (mostly California and Washington state).
But, imagine a couple of years from now, with millions of people pinning millions of sightings, providing additional information and then having the community agree on the ID? How about ecologists putting in all their field survey data (at least after publication if not before)? How about everyone who participates in the Christmas bird hunt? What an incredible database that will be! Something that one can search with machines, build and test models, and use the results to test ideas about, for instance, effects of weather events (hurricanes, fires, floods, El Nino, etc.) or broader weather changes (e.g., Global Warming).
In order for this database to become useful, I hope that the developers, as soon as possible, make sure it is possible for all the info to be machine searchable. And also to provide, perhaps, various fields that will lure people to put in more information. Right now, there is a date when the pin is posted, but the date of actual sighting is much more important. Exact latitude and longitude. Perhaps altitude. Perhaps depth for aquatic organisms. Exact time of day of the sighting. Description of the habitat. Number of individuals. Measurements of different kinds (one often cannot infer from pictures if the critter is 3cm or 30cm long, for instance). Behavioral observations. And of course the ID.
Such a database would be biased of course. People will tend to record when they see something unusual, or cool, or charismatic megafauna, rather than grass or field of corn or a bunch of squirrels in a tree. Also, more critters will be found in urban areas, on farms, in parks and by the roadsides than in places where one needs climbing (or diving) gear, or an hour of work with a machete in order to get to the habitat. But ecological models using the database could be made to account for these biases anyway.
In any case, I urge you to bookmark this site, and to use it. And let’s see how it shapes up over time.

Why do earthworms come up to the surface after the rain?

ResearchBlogging.orgBelieve it or not, this appears to have something to do with their circadian rhythms!
Back in the 1960s and early 1970s, there was quite a lot of research published on the circadian rhythms in earthworms, mostly by Miriam Bennett. As far as I can tell, nobody’s followed up on that work since. I know, from a trusted source, that earthworms will not run in running-wheels, believe it or not! The wheels were modified to contain a groove down the middle (so that the worm can go only in one direction and not off the wheel), the groove was covered with filter paper (to prevent the worm from escaping the groove) and the paper was kept moist with some kind of automated sprinkler system. Still, the earthworms pretty much stood still and the experiments were abandoned.
Dr.Bennett measured locomotion rhythms in other ways, as well as rhythms of oxygen consumption, light-avoidance behavior, etc. With one of my students, some years ago, I tried to use earthworms as well – we placed groups of worms in different lighting conditions (they were inside some soil, but not deep enough for them to completely avoid light) – the data were messy and inconclusive, except that worms kept in constant light all laid egg-cases and all died (evolutionary trade-off between longevity and fecundity, or just a last-ditch effort at reproduction before imminent death?). Worms in (short-day and long-day) LD cycles and in constant dark did not lay eggs and more-or-less survived a few days.
I intended to write a long post reviewing the earthworm clock literature, but that was before I got a job….perhaps one day. But the news today is that there is a new paper that suggests that clocks may have something to do with a behavior all of us have seen before: earthworms coming out to the surface during or after a rain.
In the paper, Role of diurnal rhythm of oxygen consumption in emergence from soil at night after heavy rain by earthworms, Shu-Chun Chuang and Jiun Hong Chen from the Institute of Zoology at National Taiwan University, compared responses of two different species of earthworms, one of which sufraces during rain and the other does not. They say:

Two species of earthworms were used to unravel why some earthworm species crawl out of the soil at night after heavy rain. Specimens of Amynthas gracilis, which show this behavior, were found to have poor tolerance to water immersion and a diurnal rhythm of oxygen consumption, using more oxygen at night than during the day. The other species, Pontoscolex corethrurus, survived longer under water and was never observed to crawl out of the soil after heavy rain; its oxygen consumption was not only lower than that of A. gracilis but also lacked a diurnal rhythm. Accordingly, we suggest that earthworms have at least two types of physical strategies to deal with water immersion and attendant oxygen depletion of the soil. The first is represented by A. gracilis; they crawl out of the waterlogged soil, especially at night when their oxygen consumption increases. The other strategy, shown by P. corethrurus, allows the earthworms to survive at a lower concentration of oxygen due to lower consumption; these worms can therefore remain longer in oxygen-poor conditions, and never crawl out of the soil after heavy rain.

So, one species has low oxygen consumption AND no rhythm of it. It survives fine, for a long time, when the soil is saturated with water. The other species has greater oxygen consumption and is thus more sensitive to depletion of oxygen when the ground is saturated with water. Furthermore, they also exhibit a daily rhythm of oxygen consumption – they consume more oxygen during the night than during the day. Thus, if it rains during the day, they may or may not surface, but if it rains as night they have to resurface pretty quickly.
Aydin Orstan describes the work in more detail on his blog Snail’s Tales, and he gets the hat-tip for alerting me to this paper.
Chuang, S., Chen, J.H. (2008). Role of diurnal rhythm of oxygen consumption in emergence from soil at night after heavy rain by earthworms. Invertebrate Biology, 127(1), 80-86. DOI: 10.1111/j.1744-7410.2007.00117.x

Spiders and Bycicles

From The Archives
Since everyone is posting about spiders this week, I though I’d republish a sweet old post of mine, which ran on April 19, 2006 under the title “Happy Bicycle Day!” I hope you like this little post as much as I enjoyed writing it:

Continue reading

Clocks and Migratory Orientation in Monarch Butterflies

Blogging on Peer-Reviewed Research

I had no time to read this in detail and write a really decent overview here, perhaps I will do it later, but for now, here are the links and key excerpts from a pair of exciting new papers in PLoS Biology and PLoS ONE, which describe the patterns of expression of a second type of cryptochrome gene in Monarch butterflies.
This cryptochrome (Cry) is more similar to the vertebrate Cry than the insect Cry, also present in this butterfly. The temporal and spatial patterns of expression of the two types of Cry suggest that they may be involved in the transfer of time-information from the circadian clock to the brain center involved in spatial orientation during long-distance migration.
The PLoS Biology paper looks at these patterns of expression, while the PLoS ONE paper identifies a whole host of genes potentially implicated in migratory behavior, including the Cry2. Here is the PLoS Biology paper:
Cryptochromes Define a Novel Circadian Clock Mechanism in Monarch Butterflies That May Underlie Sun Compass Navigation:

During their spectacular fall migration, eastern North American monarch butterflies (Danaus plexippus) use a time-compensated sun compass to help them navigate to their overwintering sites in central Mexico. The circadian clock plays a critical role in monarch butterfly migration by providing the timing component to time-compensated sun compass orientation. Here we characterize a novel molecular clock mechanism in monarchs by focusing on the functions of two CRYPTOCHROME (CRY) proteins. In the monarch clock, CRY1, a Drosophila-like protein, functions as a blue-light photoreceptor for photic entrainment, whereas CRY2, a vertebrate-like protein, functions within the clockwork as the major transcriptional repressor of the self-sustaining feedback loop. An oscillating CRY2-positive neural pathway was also discovered in the monarch brain that may communicate circadian information directly from the circadian clock to the central complex, which is the likely site of the sun compass. The monarch clock may be the prototype of a clock mechanism shared by other invertebrates that express both CRY proteins, and its elucidation will help crack the code of sun compass orientation.

Here is the editorial synopsis:
In Monarchs, Cry2 Is King of the Clock:

Back in the brain, the authors showed that Cry2 was also found in a few dozen cells in brain regions previously linked to time-keeping in the butterfly, and this Cry2 underwent circadian oscillation in these cells, but not in many other cells that were not involved in time keeping. By taking samples periodically over many hours, they found that nuclear localization of Cry2 coincided with maximal transcriptional repression of the clockwork, in keeping with its central role of regulating the feedback cycle. This is a novel demonstration of nuclear translocation of a clock protein outside flies.
Finally, the authors investigated Cry2′s activity in the central complex, the brain structure that is believed to house the navigational compass of the monarch. Monarchs integrate information on the position of the sun and the direction of polarized light to find their way from all over North America to the Mexican highlands, where they spend the winter. Cry2, but not the other clock proteins, was detected in parts of the central complex where it undergoes strong circadian cycling. Some cells containing Cry2 linked up with the clock cells, while others projected toward the optic lobe and elsewhere in the brain.
Along with highlighting the central importance of Cry2 in the inner workings of the monarch’s clock, the results in this study suggest that part of the remarkable navigational ability of the butterfly relies on its ability to integrate temporal information from the clock with spatial information from its visual system. This allows the monarch to correct its course as light shifts across the sky over the course of the day. Other cues used for charting its path remain to be elucidated.

This is the PLoS ONE paper:
Chasing Migration Genes: A Brain Expressed Sequence Tag Resource for Summer and Migratory Monarch Butterflies (Danaus plexippus):

North American monarch butterflies (Danaus plexippus) undergo a spectacular fall migration. In contrast to summer butterflies, migrants are juvenile hormone (JH) deficient, which leads to reproductive diapause and increased longevity. Migrants also utilize time-compensated sun compass orientation to help them navigate to their overwintering grounds. Here, we describe a brain expressed sequence tag (EST) resource to identify genes involved in migratory behaviors. A brain EST library was constructed from summer and migrating butterflies. Of 9,484 unique sequences, 6068 had positive hits with the non-redundant protein database; the EST database likely represents ~52% of the gene-encoding potential of the monarch genome. The brain transcriptome was cataloged using Gene Ontology and compared to Drosophila. Monarch genes were well represented, including those implicated in behavior. Three genes involved in increased JH activity (allatotropin, juvenile hormone acid methyltransfersase, and takeout) were upregulated in summer butterflies, compared to migrants. The locomotion-relevant turtle gene was marginally upregulated in migrants, while the foraging and single-minded genes were not differentially regulated. Many of the genes important for the monarch circadian clock mechanism (involved in sun compass orientation) were in the EST resource, including the newly identified cryptochrome 2. The EST database also revealed a novel Na+/K+ ATPase allele predicted to be more resistant to the toxic effects of milkweed than that reported previously. Potential genetic markers were identified from 3,486 EST contigs and included 1599 double-hit single nucleotide polymorphisms (SNPs) and 98 microsatellite polymorphisms. These data provide a template of the brain transcriptome for the monarch butterfly. Our “snap-shot” analysis of the differential regulation of candidate genes between summer and migratory butterflies suggests that unbiased, comprehensive transcriptional profiling will inform the molecular basis of migration. The identified SNPs and microsatellite polymorphisms can be used as genetic markers to address questions of population and subspecies structure.

Here is an article written after the press release, which, as such articles usually do, greatly overstates the extent of the findings:
Clocking monarch migration:

In previous work, Reppert and his team showed that pigment-producing genes in the monarch eye communicate with the butterfly’s circadian clock. As part of the new study, Reppert and his team also found, in an area of the monarch brain called the central complex, a definitive molecular and cellular link between the circadian clock and the monarch’s ability to navigate using the sun. Briscoe said that Reppert’s study was “really going to overturn a lot of views we had about the specific components of circadian clocks.”

The spatial and temporal patterns of expression make Cry2 the most serious candidate for the connection between the clock and the Sun-compass orientation mechanism. Much work, both at the molecular and at higher levels of organization needs to be done to figure out the exact mechanism by which this animal, during migration, compensates for the Sun’s movement across the sky during the day, and thus does not stray off course. Cry2 appears to be a good molecular “handle” for such studies.
For background, see my older post on the initial discovery of Cry2 in Monarch butterflies by the same team.

The Joys of Blogging Biology

One cool thing about being a blogging biologist is that one can write every day about sex with a straight face and then blame readers for “having a dirty mind”. But sex is so interesting – life would cease to exist without it and it is a central question in biology, so we have a license, nay, duty, to write about it all the time. We get all blase about it, I guess, compared to “normal people”. ;-)
One cool story that revolves around sex is making the rounds of the science blogosphere today. Jake Young explains in seemingly dry scientific language:

This issue has spawned a variety of weird behaviors and adaptations. For example, the males have spines on their intromittent organs (read: insect penises) that puncture the females insides. This is to discourage them from mating with other males. In response the females kick the males during mating to limit the damage done by the spines.
——————-snip—————-
The nuptial gift in part makes up for the reproductive cost of mating to the females, which is high in this case, but Edvardsson argues that this is probably not how it evolved. Instead, the large ejaculate probably evolved first so that the male would have more sperm to compete with other males. Then, the female evolved a way to utilize the water and nutrients in that already present sperm. “Well, hey…it’s here.”

Mo the Neurophilosopher adds the scary pictures while retaining the dry scientific tone:

A cost/benefit analysis is therefore essential to the mating behaviour of the female. The number of mating events must be strictly limited because of the resulting harm. But at the same time, the female’s needs for both sperm and water must be met.

The beauty of Pondering Pikaia is her ability to cut through all the complexity and say it like it is:

basically, females will trade sex for drinks
—–snip—–
possibly the most brutal looking sex organ I have ever seen.

So, go ahead and chuckle, you readers with dirty minds, but this is a really cool evolutionary story and if titillation brings in lay readers and gets them interested in the theory behind the scientific finding all the better. This is a good example of framing, isn’t it? Got your attention and got you interested in the underlying science, didn’t it?
Update: I see that Kate also joined the fray:

And no, he doesn’t believe that these findings generalize to other species. Including humans. So, if you’re planning to proposition a female beetle anytime soon, remember to bring along a bottle of water. You should be just fine.

Aphids and Enemies

You really don’t want to be an enemy of the aphids – two papers today! The first is quite straightforward:
Aphids Make ‘Chemical Weapons’ To Fight Off Killer Ladybirds:

Cabbage aphids have developed an internal chemical defence system which enables them to disable attacking predators by setting off a mustard oil ‘bomb’, says new research. The study shows for the first time how aphids use a chemical found in the plants they eat to emit a deadly burst of mustard oil when they’re attacked by a predator, for example a ladybird. This mustard oil kills, injures or repels the ladybird, which then saves the colony of aphids from attack, although the individual aphid involved usually dies in the process.

So, these aphids directly defend themselves against their own enemies by using the chemicals they derives from the plants they eat. But the next study introduces more complexity – several levels of the food web (i.e., tri-trophic relationship);
High Susceptibility of Bt Maize to Aphids Enhances the Performance of Parasitoids of Lepidopteran Pests:

Concerns about possible undesired environmental effects of transgenic crops have prompted numerous evaluations of such crops. So-called Bt crops receive particular attention because they carry bacteria-derived genes coding for insecticidal proteins that might negatively affect non-target arthropods. Here we show a remarkable positive effect of Bt maize on the performance of the corn leaf aphid Rhopalosiphum maidis, which in turn enhanced the performance of parasitic wasps that feed on aphid honeydew. Within five out of six pairs that were evaluated, transgenic maize lines were significantly more susceptible to aphids than their near-isogenic equivalents, with the remaining pair being equally susceptible. The aphids feed from the phloem sieve element content and analyses of this sap in selected maize lines revealed marginally, but significantly higher amino acid levels in Bt maize, which might partially explain the observed increased aphid performance. Larger colony densities of aphids on Bt plants resulted in an increased production of honeydew that can be used as food by beneficial insects. Indeed, Cotesia marginiventris, a parasitoid of lepidopteran pests, lived longer and parasitized more pest caterpillars in the presence of aphid-infested Bt maize than in the presence of aphid-infested isogenic maize. Hence, depending on aphid pest thresholds, the observed increased susceptibility of Bt maize to aphids may be either a welcome or an undesirable side effect.

Translation: transgenic corn has somewhat more nutritional value for the aphids. Thus, there are more aphids (per plant) on such corn. Thus, there is more “honeydew” (per acre) that they produce. Thus, there is more food (per acre) for the wasp. Thus, there are more wasps in the field. Thus, they are better able to control the population of moth caterpillars. Thus, there are fewer caterpillars to eat the corn. Final result: the farmer is happy. Now go to the paper itself and add comments, annotations and ratings to it.

Horseshoe crabs

Such fascinating creatures! If you have missed it so far, don’t miss it now – the two-part series by Mark H on DailyKos:
Marine Life Series: Horseshoe Crab Basics
Marine Life Series: Horseshoe Crab Anatomy
One day when I find some time, I’ll have to write a long detailed post about the fascinating aspects of the circadian system and vision in the horseshoe crab (oh, some of which was done by Erik Herzog, so you know I like the stuff!).

Garden-Variety Experiment

Literally. If you want to know how to figure out what your slug has eaten today, just ask Aydin.

Invisibility Cloak

When I was a kid I swallowed science-fiction by the crates. And I was too young to be very discerning of quality – I liked everything. Good taste developed later, with age. But even at that tender age, there was one book that was so bad that not only did I realized it was bad, it really, really irked me. It was The Ayes of Texas (check the Amazon readers’ reviews!), a stupid 1982 Texas-secessionist fairy-tale in which a rich (and of course brilliant and smooth with ladies) conservative Texan, by throwing millions of dollars at scientists, gets all sorts of new gizmos and gadgets which he uses to win the Cold War by defeating both the Soviet and the US military, ending with Texas as the remaining standing military superpower. Hey, at that age I barely new where Texas was but the whole schtick was so sick, not to mention the stupid idea that scientific discovery can be bought just like that, with bags of money and few weeks of effort!
Anyway, since I doubt you’d care if I spoiled the plot of a book that you will not and should not read, the key weapon in the battle was an old WWII battleship armed with new types of weapons and, most importantly, made invisible by being plastered with panels made of a new material (which, if I remember correctly, break several laws of physics).
And while the invisibility panels as described in the book were impossible, that does not mean that nobody’s ever looked at the possibility of making materials that can make stuff more-or-less invisible. There was a report last year that saw a lot of press, and recently a new one came out, looking at chemicals called reflectins, coded by six genes unique to squid. Cephalopods rule, of course, and the distribution of reflectins in the skin is under the neural control of melanophores in cuttlefish and octopods.
Now, as MC explains very well, a new paper came out describing the properties of reflexins inserted into and expressed in E.coli. Then, reflexin synthetized by bacteria were coaxed into forming films on the surface of water and the light-reflecting properties were studies under varying conditions. You’ll have to read MC’s post for details.
Anyway, as MC notes, this is clearly of interest to the military, though I doubt they’ll ever use the synthetic reflexins to coat a WWII-era warship in order to defeat both the Soviet and the US armies in order to secede and form a Greater Texas.

Everything you always wanted to know about crayfish but were too afraid to ask….

If (like me) you have a special fondness for crayfish, then this post by Burning Silo is a Must Read of the day!

Responsible consumption of shrimp

I love seafood, but I eat it quite rarely. About a third of my old Department did fisheries and aquaculture science so I’ve seen many seminars and Thesis defenses on the topic and am quite aware of the problems with the world’s fisheries stocks.
I also prefer freshwater fish – I grew up on the Danube and my Mom fixes the best Fish Soup in the history of the Universe.
But, if you like seafood and you want to eat shrimp occasionally, yet you want to act in an environmentally responsible way, you need to know quite a lot about ecology, about behavior and natural history of shrimp, about the methods of harvesting and/or farming shrimp, about the way shrimp are processed and marketed. Armed with all that information, you’ll know where, when, how, how often and from whom to buy shrimp. It is not easy to find all that informaiton, but now you can find it all in one place.
Mark H (better known around science blogs as the person running the Biomes Blog), as a part of his marvelous Marine Life Series, has put it all together here.
He even provides a recipe at the end, which looks promising – I may try to use it one day, once I figure out how to find environmentaly not-so-bad shrimp around here.

Invertebrate blogging of the month

Circus of the Spineless #16 is up on The force that through…

Cephalopods don’t need a mirror test – they are mirrors themselves .

PZ probably already knows about this, but I found this discovery of super-reflective skin cells in squid, cuttlefish and octopus quite amazing!

Hanlon’s team discovered that the bottom layer of octopus skin, made up of cells called leucophores, is composed of a translucent, colourless, reflecting protein. “Protein reflectors are very odd in the animal kingdom,” says Hanlon, who is a zoologist. What’s even more odd is just how reflective these proteins are — they reflect all wavelengths of light that hit at any angle. “This is beautiful broadband reflection,” Hanlon told the Materials Research Society at their meeting in Boston last month. The result is a material that looks startlingly white in white light, and blue in the bluish light found beneath the waves. “These cells also match the intensity of the prevalent light,” says Hanlon’s research associate Lydia Mathger. All this helps the creatures to blend into their surroundings.

Hat-tip: Matt Dowling

Invertebrate blogging of the month

Circus of the Spineless #14 is up on Neurophilosopher’s blog

New study on evolution of vision

For easy-to-understand quick look at the evolution of vision I have to refer you to these two posts by PZ Myers, this post of mine, and these two posts by Carl Zimmer.
Now, armed with all that knowledge, you will curely appreciate the importance of this new study:
Compound Eyes, Evolutionary Ties:

Biologists at the University of California, San Diego have discovered that the presence of a key protein in the compound eyes of the fruit fly (which glow at center due to a fluorescent protein) allows the formation of distinct light gathering units in each of its 800 unit eyes, an evolutionary change to an “open system” that enabled insects to make significant improvements in visual acuity and angular sensitivity. In contrast, beetles (shown surrounding the fruit fly), bees and many mosquito species have the light-gathering units fused together into a “closed system.”
In a paper published in this week’s early online edition of the journal Nature, the scientists report that one of three proteins needed to form these light gathering units is present in the visual system of fruit flies, house flies and other insects with open eye systems, but conspicuously absent in beetles, bees and other species with closed systems. The researchers showed that the loss of this protein, called “spacemaker,” can convert the eyes of fruitflies–which normally have open eye systems–into a closed one. In contrast, the introduction of spacemaker into eyes with a closed system transformed them into an open one.
Charles Darwin was so enamored by the intricate complexity of the eye that he wondered how it could have evolved. “These results help illustrate the beauty and power of evolution and show how ‘little steps’–like the presence of a single structural protein–can so spectacularly account for major changes in form and function,” said Charles Zuker, a professor of biology and neurosciences at UCSD and a Howard Hughes Medical Institute investigator, who headed the research team.

Diversity of insect circadian clocks – the story of the Monarch butterfly

Blogging on Peer-Reviewed Research

Diversity of insect circadian clocks - the story of the Monarch butterflyFrom January 20, 2006, on the need to check the model-derived findings in non-model organisms.

Continue reading

Spineless in a Tattoo Parlor

You are going to love the latest Circus of the Spineless, now up on Deep Sea News!

Revenge of the Zombifying Wasp

Revenge of the Zombifying WaspOne of the coolest parasites ever (from February 04, 2006):

Continue reading

Cooperative Hithhiking

Baby bugs team up for sex scam

The moment they’re born, beetles of one species join forces for a curious drill.

The larvae hatch out of their eggs and together, as a group, climb to the tip of the plant. There, they secrete a sex pheromone that attracts a male of a bee who tries to couplate with the ball of larvae. They jump on him. He flies away carrying the little buggers.
When he finds a female to mate with, the larvae jump ship and go away hithhiking on her. When she goes back to her nest they disembark, eat the nectar she collected and her eggs before their final metamorphosis.
Arthropods are known to hitch rides on other animals, including larger arthropods, but this is the first documented case of a group hithchiking together.

Spineless for a year

Circus of the Spineless #12 is up on Sunbeam from Cucumbers. I can’t believe it’s already been a year since this fine carnival started!

Another time-scale in insect brains

Bumble Bees Can Estimate Time Intervals:

In a finding that broadens our understanding of time perception in the animal kingdom, researchers have discovered that an insect pollinator, the bumble bee, can estimate the duration of time intervals. Although many insects show daily and annual rhythms of behavior, the more sophisticated ability to estimate the duration of shorter time intervals had previously been known only in humans and other vertebrates.
————-snip——————
Bees and other insects make a variety of decisions that appear to require the ability to estimate elapsed durations. Insect pollinators feed on floral nectar that depletes and renews with the passage of time, and insect communication and navigation may also require the ability to estimate the duration of time intervals.
In the new work, the researchers investigated bumble bees’ ability to time the interval between successive nectar rewards. Using a specially designed chamber in which bumble bees extended their proboscis to obtain sucrose rewards, the researchers observed that bees adjusted the timing of proboscis extensions so that most were made near the end of the programmed interval between rewards. When nectar was delivered after either of two different intervals, bees could often time both intervals simultaneously. This research shows that the biological foundations of time perception may be found in animals with relatively simple neural systems.

Neurons developing out ot Mesoderm?!

Snuck into the very end of this, otherwise very interesting article on neurobiology of cephalopods and moths, is this little passage:

As for flies, Tublitz outlined a tantalizing question, as yet unanswered, that has continued to take flight out of his lab for the last decade. Scientists for years, he said, have held “one hard rule” about what constitutes a neuron — that a neuron cell always arises from the ectoderm of a developing embryo. However, a discovery in Drosophila — fruit flies — has softened that assumption.
Cells arising from the mesoderm rest in a layer on top of the fruit fly’s nervous system, Tublitz explained. “These cells have all of the properties of nerve cells.” A slide shown during his talk displayed a long list of characteristics most often applied, with only few exceptions, to neurons. “Are these mesodermal cells nerve cells? I can’t answer that question conclusively, but we have generated data that suggest the answer may be ‘yes’.”

Friday Weird Sex Blogging – Losing Your Head For Love

As always, animal porn is under the fold:

Continue reading

Daily Rhythms in Cnidaria

Blogging on Peer-Reviewed Research

The origin and early evolution of circadian clocks are far from clear. It is now widely believed that the clocks in cyanobacteria and the clocks in Eukarya evolved independently from each other. It is also possible that some Archaea possess clock – at least they have clock genes, thought to have arived there by lateral transfer from cyanobacteria.[continued under the fold]

Continue reading