I went to the second
In any event the lecture last night was on hermit crabs. I spend a lot of time with hermit crabs at my job right now so it was nice to learn a little bit more about them. The lecturer, Randi Rotjan, is a post-doc fellow at the NEAq and spends most of her time studying corals but during one trip to
The basic focus of her research on these animals is on vacancy chains. This is what happens (not just with hermits but with any organism that uses discrete, limited and reusable resources) when one crab chooses a new shell and leaves his old shell for another crab to occupy who then leaves his old shell behind, etc. etc. Just one switch creates a chain of switches and she has found that around 10% of the population in the wild can end up in a better shell. This process has been compared to human behavior in real estate and also with job openings.
Before going off to
Once studying these behaviors in the lab and in the field with terrestrial hermit crabs she (being a marine biologist) wanted to look at them in marine crabs. Luckily the
So gathering all that together she found two populations of pagurus longicarpus with different living conditions. One had somewhat poor conditions (more damaged shells) and the other had better conditions. It is still unclear why the different areas have these different conditions but it provided her with animals who were accustomed to different social pressures when choosing a shell. Interestingly she found no difference between the two groups in terms of how crowding and damage influencing their vacancy chains. She also found no difference in the average lengths of the vacancy chains. But what she did find were very different social behaviors in the poor condition group such as far more waiting, longer investigations of a single shell, more aggression and generally more interactions with their fellow hermits. More work is going on and I really can’t wait to see how it turns out. Seriously!
Just one more fun fact about hermit crabs: all of them, even terrestrial crabs, have a marine larval phase. I found it interesting to think that these larvae can be carried off to a new island to populate it or to introduce new competition for resources from a previously absent species. It’s a very different lifestyle from either fully marine or fully terrestrial arthropods.