Experimental Tropical Marine Ecology

Working in the Lab
by -- April 4th, 2013

The majority of the next few days were spent working in the labs with the crabs we had collected. Initially, we had to sort each one in to a separate container, and label each one. We were still feeling rather over -excited at this point, so not only did each crab receive a unique number and plastic cup, it was also given a name! In the following days, we would all get to know our crabs fairly well that ‘Are you ready for Tiberius’ would make more sense than ‘Number 62 is next’.

Our experiment had two main phases. First, we tested the crabs’ responses to a number of targets. Some were purely visual, some had just odor targets, and some had a mixture of both. We did this by placing the crab on a circular, lidded platform, lit from above and noting the degree that the crab moved in. That is to say, if the crab always walked towards north, which was aligned with 0 degrees, then 0 was written on the spread sheet. If it headed east, then 90 was recorded, and so forth. The platform had increments of 10 degrees marked on, so it was a simple matter to watch where they went, and record it.

As we had so many crabs, this took an incredibly long time! There were some points, especially during the mid afternoon, when the rest from our siestas had worn off but dinner was just too far away to imagine that energy levels would sink to the floor. One one of these occasions, we resorted to putting on loud music and doing jumping jacks, sit ups, and all manner of exercises whilst we waited for the crabs to react, simply to get blood flowing back to our brains! It worked surprisingly well, and I’m sure more than one of us will be employing this tactic in future labs sessions!

The second part of our experiment was concerted with the crabs’ comfort within their shells. This, undoubtedly, was the tricky part.

We had to remove all the crabs from their shells, weigh them, and measure both their body volume and the volume of their shell. As I’m sure you can imagine, hermit crabs do not exactly appreciate being forced out of their homes. Removing them involved incredibly hot soldering tools, nimble fingers, and the patience of a saint…

Needless to say, this too took us quite a long time, and more than one finger was pinched before the end of the night. There were also a few unfortunate incidents when we might be a little over enthusiastic with the soldering iron or the forceps, and end up only removing half the crab…  Some might call this karma for the pinches, but mostly we felt incredibly guilty.  Having spent the best part of 3 days working with Olive, Dawn Budgie, Adelle or Atlas, it was surprisingly heart wrenching to see them die.

At the end of the project, we freed as many of the crabs as we could back into the rainforest. We stood there, taking pictures and bidding goodbye to them as they scuttled off as quickly as their little legs could take them. Mind you, I’m not surprised. I wouldn’t like being put in a plastic box and made to run around for 3 days either!

 

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