Friday, May 2, 2014

Little Crab, Your house is on fire!

In previus post I told you that I was working on the study of crabs. The goal of this study is to see if there are difference in the eggs size of three species of crabs comparing the dry and wet seasons.

Which are the crabs that have difference in the egg size and why?

We choose three species of crabs, one porcellanid Petrolisthes armatus (I wrote about it in my previus post), one xanthid Xanthodius sternberghii and one hermit crab Clibanarius albidigitus. All of them live in the intertidial zone.

For both xanthids and porcellanids, the sampling is easy, I only catch the females with eggs and take them to the lab. But the hermit crabs, as you might know, live in a snail shell.  This makes it impossible to determine if they are females or males and if they have eggs in the field.

So the question is: How can I take them from the shell without hurting them and without breaking the shells?

To take the hermit crabs from the shell I´m using an alcohol lamp (Fotheringham, 1976a).  Yeah, I know it sounds weird, but it is a standard method, one that they teach you in invertebrate biology class.  After trying it, I really think it is the best way.  If you do it right,  they get out by themselves (of course, if your house is on fire you´re going to run) and after process them, I leave each with its shell and they go back home… In the video, you can see how I work with them!



video










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