You've got Crabs, Ass-face!

Apr 02, 2006 17:24

Loyal readers, I have a confession to make.  I have crabs.

Invasive ones, in fact.  Hemigrapsus sanguineus, the Asian shore crab, brought over as planktonic larvae in the ballasts of ships in the mid-90's.  Since then, these adorable little bastards have invaded tide pool environments from New Jersey to Newfoundland, causing a drastic reduction in the population of the formerly dominant species, the green crab (actually also an invader, from Europe, but they actually fit rather well into the ecosystem here).  Asian shore crabs have few if any natural predators in East coast waters, thought they sure act like they do.  Flip over any rock at Black Point and you're likely to see half a dozen of them go scuttling for cover.  In fact, they seem to share space very well.  Or do they?

This was the question behind the project for Animal Behavior thought up by myself, Heather, Nora, Lindsay, and Matt.  As I write this, a ten-gallon tank sits on the glass table in the living room not twenty feet away from me.  On the bottom of this tank is a bulls-eye pattern of labeled regions, with region 1 being in the middle and region 5 being pretty much out in the open.  There is a clump of rocks in the center of the tank serving as a home base for 14 Hemigrapsus, ranging in size from an absolute beast capable of smashing fully-grown perriwinkles to a tiny little guy fresh out of the plankton who could probably pass for a real genital crab.  Our goal: to sit underneath that tank once a day and find out if there's any kind of pecking order going on under there.

Also in the tank are several dozen perriwinkles, whose main function is to be killed and eaten.  When this happens, it causes no end of excitement for my housemates and I.  Seriously, you haven't lived until you've watched a snail get yanked right out of its shell by a hungry crustacean.

So what are our results?  Well, there's a week left of our study but so far the big fat-ass crab seems to stay parked right in the middle of the cover, devoting most of his time and energy to keeping the other large crabs off his turf.  But, we have another week to see what happens, and after today's water change the rocks have been switched around a little.  Will this affect fatty's ability to stay on his throne?  Stay tuned.

This is balls-to-the-wall marine biology, people.
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