Pinchy personalities

Like every kid who went on family outings to the NJ shore, I ended up coming home with any number of hermit crabs over the years. I'd make sure the sponge was wet, that they had food, that they were really in their shells and not just hiding elsewhere (probably terrorizing them in the process), but they generally didn't last long. My grief as to my departed pets is now made all the worse by a new paper in the Proceedings of the Royal Society B that suggests that hermit crabs have personalities. Oh Pinchy, how I miss you...

The experiment on responses of the hermit crab species Pagurus bernhardus was carried out in tidal pools along the south west coast of England, the researchers handling the shells to see if the crabs would exhibit the typical "startle response," which in this case is retreating back into the shell. After picking out a number of crabs that showed the proper response (retreating and not emerging again until after the shell had been placed back on the ground) the researchers headed back to the lab for more testing in this same manner. Overall, some crabs were more "bold" than others, consistently appearing sooner than others that spent more time in hiding. To the researchers, this suggests the presence of a personality rather than a plastic response that requires a lot of gaging of the situation to determine when it is safe. I would imagine that in areas where there are many predators, boldness might not be a good thing, but bold individuals that peeked out too early would be selected out.

The paper features a number of graphs, a bunch of data, and some acronyms, but it was a pretty simple experiment. The question is, though, did the researchers actually find evidence of personality in crustaceans? I guess that depends on what you term "personality"; if a consistent behavior in a response to a particular stimulus is indicative of a personality, then perhaps they did, but I'm not entirely convinced that the crabs were exhibiting behavior that I'd call a personality. Baboons, for instance, have personalities indicated by various behavioral interactions with other members of their social group; the personality of the animal is determined by a range of regular responses to particular situations. In the crab study, it's just one response to a perceived threat, and one factor is not nearly enough to ascribe personality to these animals, I think.

As a bit of an aside, I've been a bit disappointed by the Proceedings of the Royal Society B. Even though this paper wasn't that great it wouldn't elicit much extra comment from my by itself, but recently they published a terrible paper about the Flores hominids and they regularly publish the work of researchers that insist that the feathers preserved on dinosaurs like Sinosauropteryx are only collagen fibers. Every journal puts out some low-quality papers now and then, but I've definitely lost a bit of respect for Proceedings given the low-quality work that seems to regularly show up there.

Briffa, M., Rundle, S.D., Fryer, A. (2008). Comparing the strength of behavioural plasticity and consistency across situations: animal personalities in the hermit crab Pagurus bernhardus. Proceedings of the Royal Society B: Biological Sciences, -1(-1), -1--1. DOI: 10.1098/rspb.2008.0025