Can I mark the shells?

[metfan]

Hi. I'm still relatively new to crabs. When my daughter brought them home, they were in awful painted shells. Thanks to this board, I became a good mom and set up a lovely crabitat and new natural shells. All three picked green turbo shells almost immediately. I have one down molting. I cannot really tell them apart. I would like to keep track of molting and behavior. Can I mark the shells somehow? A small dot with a sharpie? Advice? Thanks.

[emceedi]

I'm not sure about Sharpie. I know they say they're non-toxic, but crabs are more sensitive to chemicals than we are. I would suggest trying to etch markings onto empty shells with a little metal file or something. I know it's a little too late for the shells that already have a crab moved into them. Maybe somebody else will have suggestions on safe ways to maker shells.

[megmaholm]

I don't really know of a safe way to mark the shells, and if they switch out of them or swap them you'll get even more confused! What I do is take pictures of my crabs' big pinchers and body and try to keep the pics updated so I can tell them apart. Most crabs have pretty distinctive BPs.

[wodesorel]

I once took a day and recorded who every crab was, and when I woke up the next morning some had changed and some had swapped. Marking shells is no guarantee!

[Spags]

I would have to agree with whoever said to take a picture of their big claw, as most have pretty distinct and individual big claws.

[Kleinerhejhog]

I know their colors can change when they molt, do their markings change too?

[wodesorel]

Yes, markings can change as well as color, sometimes dramatically. One of the admins says she can tell hers apart by the setae pattern on the claw, but I have 6 years worth of photo records with Goji and his have changed every molt. Supposedly the teeth in the pincher stays the same, but again his hasn't. It might be something that varies crab to crab.

[Kleinerhejhog]

Dang. Nothing static, huh? Metfan, I think we're doomed, lol...

[wodesorel]

Their eye shape and antenna shape seem to be pretty stable, as is the way they hold themselves. I can tell my old guard apart for the most part, and it's by the way they sit. With Goji it's all in his antennas, he has a very distinctive arch to them. There's one that I adopted that has extremely distinctive leg hair which no other crab in the tank has, and it's stayed the same through molts. Another is the only one in the tank who has blue& brown on his claws and knees, and he's been that way for five years even though his body color has changed. Each crab seems to have something that stays constant from molt to molt, but figuring out what that one thing is takes a while.

[Kleinerhejhog]

Hmm, so now they just have to come out of hiding so they can be studied, lol...