HCA: Hermit Crab Association

or to better explain the subject, i'm trying to find out any experiences people have had with their hermies that have encouraged shell changes. Obviously optimum surroundings play a big part, and i've already considered that, but i'm wondering if anyone may have noticed something that has triggered shell changes.I'm exploring the benefits and limitations of shell changes, and comparing various variables of shells to get a better understanding of the influences the crab uses to determine which is the best shell to use as protection, so as you can imagine, to test this I need the crabs to be in a situation where they are willing to change shells. Temperature, humidity and outgrowth are already considered, so i'm searching for something that may be a bit more subtle but that seems to have a noticable effect on their shell changing behaviour. Any input greatly received, and any questions people may have about my study i'd be happy to answer (Bear in mind i'm still in pre-test and research stages so they might be a bit limited in depth).Thank you for your time.

Salt water. One way we use to encourage shell changes is to boil the shells, then put a little salt water in the mouth of the shell. It makes the shell hard to resist. Doesn't work every time, of course, but more than mere coincidence would suggest. People also have used buffers and drills and such to smooth the mouths of shells. That also encourages a crabby to change. In the wild, and in some tanks, one shell change will trigger a chain response. In the wild, it's understandable. Shells are scarce, and if one new one becomes available, everyone gets a shot at a better fitting shell. I would presume that when this happens in tanks where shells are not scarce, it's instinct kicking in. It's pretty common knowledge on hermie boards like this one that certain species prefer different shells. Es and Ruggies tend to like D shaped openings, while PPs, Indos and Straws tend to go for the rounder ones, like turbos. We know that hermies obviously like a smooth, strong but light shell, but sometimes they pick weird choices! Like hermies who go into big heavy murexs. For protection? I suppose it could explain it, except that some people said that their hermies have gone into those really long spiralled shells that were put in the tank for decoration. The hermies cannot maneuver well in them, so they really don't make a whole lot of sense. I hope this helps.

Bizarrely, shell changes in my tank are almost lately (in the past two years or so) triggered by a purchase of new shells. The crabs seem to really know that they have never seen these shells before, whereas even with switching the old ones around, alternating them, rinsing them with salt water, etc. they rarely show interest in them once the peak of newness wears off. I don't pretend to think that this shows signs of higher intelligence in the crabs , but there must be something about new shells that makes the crabs highly interested in them even when they're the same kind as the older shells. Alternately, if one crab changes his shell the others will flock over to the one he left behind, presumably because it's already been field-tested and revealed to be a safe choice.

Well, every shell's unique so may fit better than another, even if it's from the same species as others offered.

I have had changes due to the appearance of new shells, which prompted me to rotate the shell collection every few months, and due to another changing shells. Not quite the line up to change that you read about on the seashores, but it was definately a crab waiting patiently to move into the vacated shell.

Well the idea of my study is to bring about an explanation for the reasoning behind their odd choices of shell behaviour. My theory is that the crabs are able to choose a shell not only for its size, but by the benefit of weight versus thermal conductivity. There's a lot of instances where hermies "hang out" of their shells when too warm, and this led me to wonder if presenting them with a thinner shell would they switch to that shell to reduce the amount of heat retained within it. I'll no doubt be asking around here more for various bits of info. I shall give the salt water method a test run on my current crabs and hopefully I will be able to expand this to a larger collection and see how well it does in a larger collection of crabs.

quote:My theory is that the crabs are able to choose a shell not only for its size, but by the benefit of weight versus thermal conductivity. Yes def. We all know that most crabs prefer a light weight shell that is easy to carry and will keep them the right temp, not too hot but not too cold. That is def a factor in picking a shell. They also like the ones that are smooth and comfortable. Crabs also will reach up and pinch off pieces of shell in front of their eyes to "custom fit" their shell.