Welcome to Felicia's Aquarium Adventures, your number one source for pet Crinoid Squat Lobster information!
A couple weeks ago, I was happy to find a large white and yellow Allogalathea elegans that I think was a female. Similar Galatheid crabs can be sexed by the width of the carapace; females have a wider carapace than the males for carrying eggs. But another close relative, the porcelain crab, the females are significantly smaller than the male. Either way, I think there is a difference in width between male and female Crinoid squat lobsters.
The photo above is a wild gravid female Crinoid squat lobster in its host. Most of the squat lobsters I see are probably juveniles or males, so I don't often see the ones with wider bodies, like the one pictured below.
Allogalathea elegans and my Galathea inflata sharing a Crinoid, I had the idea to try to make a pair of one of my squat lobsters. I've talked to divers who say it's rare to see more than one squat lobster on a Crinoid in the wild. No one is quite sure if they live as pairs or prefer solitude. Sadly, the new squat lobster didn't live through acclimation. My dreams of having a pair of squat lobsters were dashed.
I did find another yellow squat lobster soon after, but I believe it is either a male or a juvenile. I bought him and added him to my aquarium where he started a game of musical Crinoids with the other squat lobsters.
I've never actually seen my squat lobsters battle, but I see the aftermath. There are two Crinoids in my aquarium, both are black. They've been alive, honestly, longer than I expected. One is in pretty good shape still, and it is the preferred Crinoid. The other lost the tips of its arms long ago. Darth Maul, my 2+ year old Galathea inflata, in August was sharing the good Crinoid with Darth Vader, an Allogalathea elegans who has been with us about 6 months. For a few weeks, it seemed like a truce had been struck between the two. Then one day, I woke up to find Darth Maul's molt under the good Crinoid. Darth Vader was there, but Darth Maul was missing. When I finally found him, he was in the small Crinoid and missing an arm. There must have been a feirce battle while Darth Maul was molting and Darth Vader found him in a weakened state.
Squat lobster status quo was reached and maintained until a third squat lobster, the yellow and white one my husband dubbed "Bananarama II" was added to the aquarium. This is when the game of musical Crinoids commenced. The next day, Bananarama was in the small Crinoid, Darth Maul was in the preferred Crinoid, and Darth Vader was alone. The day after that, Darth Vader took the small Crinoid from Bananarama, who I found on the complete other side of the 4 foot aquarium. Here he is next to my special-needs goby and laying claim to this empty snail shell
Chucks' addiction has a beautiful gallery of hitchhiking Galatheid squat lobsters.