Over the past few weeks I found a couple of unusual animals in my education trawls. Both of my new friends were caught in the same net pull. One was something that, while rare, I’ve encountered a handful of times. The second critter is something that I’ve seen before, but never caught alive in any of the hundreds of trawls I’ve done.
The first animal is a common or brown spiny sea star. What makes this one uncommon, however, is the fact that it has six arms rather than five! Also, close examination of the photograph revealed that the sea star appears to have multiple madreporites, which is the organ that they use to control the amount of water in their bodies. They usually only have one. It seems the extra leg may have emerged after the body got damaged, but this is just a guess. One other thing that is exciting about this sea star is that it is the first one that I’ve encountered in the backwaters following hurricane Irma!
The second surprising critter is a tiny baby calico crab. Calicos are one of my favorite animals and I’ve never caught a live one in a trawl before. These crabs, or parts of them anyway, are sometimes encountered on the beach after storms. Their white carapace (top of the shell) is covered in pink and purple leopard spots that seem improbable/impractical for any type of camouflage – but hey, it apparently works for them. These crabs burrow in the sand and are likely more active at night which might account for the fact that, other than by crabbers, most of us don’t get to see these beautiful crabs often.
I was really excited about catching the little crab – especially because it was so little. The crab was so small that it would fit on your pinky fingernail. I wanted to bring the crab up to our learning center so that we could share it with students and watch it grow, so it could eventually be used in our touch tank (calicos are not particularly pinchy like most crabs). When I was getting ready to bring it up to the ELC after cleaning the boat, I noticed that it was beginning to develop a bit of bubble butt. The crab looked a bit unusual so I left it alone for a few minutes in its transport jar then checked on it again. Its protruding backside was getting even bigger and it was clear that the crab was starting to molt right there in the classroom. In just a few minutes its new exoskeleton (shell) had swollen enough that it crawled out with a whole new body, which was soft and vulnerable. The speed in which it molted was surprising as well as how much it grew in a single molt. The photograph of the calico crab is just the cast-off old exoskeleton, because I didn’t want to stress the newly grown crab out any more – at least not until its shell had hardened and it was more able to take on the world!
The sea star and the crab are not on display yet. We are giving them a chance to grow a bit before they move to new homes in a focus tank or in the touch tank. Come by and see them soon!
Dave Graff, Education Specialist