zebra crab

[mollymonticello]

Does anyone know anything about zebra crabs? When you do a google search, only picture websites come up. I'm wondering if they are omnivores or carnivores.

[charlesr1958]

Not sure what a zebra crab is, but all crabs are omnivores, willing to get by on algae,detritus if need be, yet quite capable of taking advantage of meatier table fare when the opportunity arises.

Chuck

[LeslieH]

It's Zebrida adamsii. It's one of the exceptions Chuck. This species is an obligate symbiont on some species of sea urchins. All members of the family are echinoderm symbionts.

Despite the fact it lives on the outside of urchins it can be classified as a parasite because it feeds on the appendages and skin of the host urchin. While it may be relatively benign in the wild where it can switch from urchin to urchin in a tank it will eventually cause the death of the host.

[mollymonticello]

Hello, Leslie. Thanks for the information. I didn't know they ate their host. I read that in the wild they host on fire urchins. I don't have any sea urchins in my tank. So far my zebra crab has just been hanging out on my gorgonians. I'm not sure if that's because he likes the gorgonians, or if it's just because most of my corals are gorgonians. I hope he won't starve without an urchin. If that's the case, I could supply him with urchins for food. I know fire urchins are a lot bigger than the little pincushion urchins at my LFS. But it's worth a try.

[charlesr1958]

As always Leslie, thanks! I tried to google "zebra" but came up with a lot of garbage as usual. Will have to start taking closer looks at urchins now...lol

Chuck

[LeslieH]

Molly - I don't know if it will only feed on urchins or if it will eat other things as well. If it's starving it may well try to eat other things. Getting it an urchin is probably best but you could give it something meaty & see what happens. Good luck --

[mollymonticello]

I've been squirting it with mysis/cyclops mixtures, but it is so slow moving it doesn't catch any or seem to want to catch any. It was hanging out at the base of my gorgonian yesterday and picking (very slowly) at some algae at its base. I didn't see it put its claw in its mouth, but it was picking at something there. Maybe there were pods in the algae. I'm going to grab a little pincushion urchin at my LFS this week and see what happens.

[cbr600rri]

What Leslie said, target feed it with something meaty should work.

[finsurgeon]

I've had one for a couple of years. I think they like diadema (black long-spine) urchins the best, and I've posted before that they seem to eat the urchin's spines. I have 2 long spine black urchins, 2 blue tux, 1 pink rainbow pin cushion, 1 purple rock-boring, and 1 purple impact urchin, and while the crab may switch onto another type for a day or 2, he always ends up back on the black ones. I don't think it harms them, and in fact it has allowed me to keep urchins that otherwise would have gotten too big for my tank very quickly. In effect, he keeps them "mowed". I recommend 1 crab for 2 urchins. I lost a crab about a year and a half ago, and the urchin growth was quite rapid while there was no one to "groom" them, but once I got another crab, I haven't had any turnover of crab or any urchin since. I don't think the crab has eaten any food I've fed, and I don't think he's been off of an urchin for over 3 days total. And 2 crabs didn't work - they fought over an urchin to the dismay of the smaller one.

[LeslieH]

What's happening is that the energy the urchins would normally use to grow is being diverted into continuous repair or replacement of what the crab's been eating. If you only had one urchin which couldn't heal fast enough it would eventually die.

[finsurgeon]

I agree that a single urchin is not quite enough. And the diadema or astrpyga types have the size and growth potential to support the crab best. The blue tux and pin-cushion types show wear quickly when "inhabited". Also, the all black long-spine I once had was not as good as the true diadema with the little blue spots on black.

[mollymonticello]

I got a cheap white pincushion? type urchin today, and I can say without a shadow of a doubt that this crab eats urchins. lol. I never saw it eat anything I target fed it with...mysis, cyclops, cyclop eeze, prawn eggs, rotifers, etc. But as soon as I put that urchin in the tank, it was love at first sight. The crab is now picking at the urchin's feet I think and putting little bits into his mouth. And he is a LOT more animated now, moving faster. Guess I'll have to get a couple more urchins. This one's pretty big, about 3 1/2 Inches in diameter.

[LeslieH]

You're such a good crab mommie!

[mollymonticello]

Awwww, thanks Hee hee, I wub my crabbie

His name is Ichiro, after that baseball player my husband likes. Last time I let him name anything...

The crab is doing great, hanging out on the urchin still. Let me get you some pics. Please pardon the algae on the glass.

[mollymonticello]

I got a second urchin today, thank you finsurgeon for all that excellent information!

[mamagoose45]

Very cool looking crab!

[Kemo484]

Sweet looking crab

[mollymonticello]

Except those urchins are eating all my coralline algae

[finsurgeon]

Don't despair. After they eat your coralline algae, they will poop the spores, and it will come back faster. I took my first urchin back to the store after 2 days of coralline grinding, but eventually I got another, and another, and so on. Now the tracks of my 7 urchins disappear soon after they are made.

[mollymonticello]

The good news is that they also eat a little Caulerpa. That stuff is the devil.

[charlesr1958]

Now THAT is actualy a great looking crab! Been looking at wild urchins when I can but have yet to find anything, but thats half of the fun of looking, ya just never know when.

Chuck

[LeslieH]

Be careful handling the urchins Chuck - remember some of them are venomous.

[Grunt]

How did you find that guy (in stores), was he with an urchin you purchased?

Nice looking crab.

[charlesr1958]

Thanks Leslie, I do rarely see one type of urchin (gotta get a pic of one) that I remember as being described as "deadly", it has such a potent sting that it can put you into shock. Its the basic urchin body plan (shape) but instead of spines, it is covered in what I can best describe as "rimmed circular pads", I tried to bring one home for photos once and while it was in the bucket it released a gawd awfull amount of thick snotty clear mucus and killed everything else in the bucket (fish and another urchin species) Being the moron that I am, I started scooping out the "gel" untill I realized that my hand was starting to tingle and turn red. A vocal "oh!" had Linda asking her usuall of me - "now what got you?" ...lol Anyways, I gotta get a pic of one sooner or later, very weird looking urchin.

Chuck

[LeslieH]

Poor Linda - you sure keep her hopping!

Sounds like the flower urchin Toxopneustes pileolus -
http://www.seadb.univpm.it/en_Flower...eolus_235.htm#
http://www.scuba-equipment-usa.com/m.../Flower_Urchin(Toxopneustes_pileolus).html

It does have spines but as the video in the first link shows the modified pedicellaria with expanded tips & poisonous venom are longer than the spiines.