Crab ID, pic heavy

[Tennyson]

I used to have this crab in my tank, I know nothing about it. It died though, just wondering what it is.

The first couple weeks I had it, it looked like this and burrowed in the sand and swam around the tank with some weird pumper thing in its butt, it had blue eyes and hid in the sand alot

It may have been a baby or something since it changed to this:
It had larger more prominent eyes and stopped burrowing in the sand.

Then it changed again, this is one of my best pictures of it before it died.

I think it molted and changed differently after each time. Pretty weird. Anyone know what it is?

Thanks

 

[NirvanaFan]

Looks kind of like a type of grapsid crab. Do you have a picture of it's shell from the top?

 

[Tennyson]

no

 

[JEFFR259]

Sorry about the loss, but boy, he's cool looking!!! I bet he was entertaining to observe!

 

[LeslieH]

Eyes are wrong for a grapsid. Take a look at this page to see examples of both grapsids and ocyopodids which is what I think it is.
http://www.flmnh.ufl.edu/reefs/guamimg/crustacea/crusties/Page1.html

Ocypodids are ghost and fiddler crabs. they live on beaches and mud flats. They feed by eating organics off sand/mud, leaving small round balls of discarded sediment behind. Many of them will not survive continuous immersion in seawater once they develop to a certain stage.


Crabs undergo a lot of changes during the planktonic and settlement stages of development. These pages have photos of various stages:
http://www.bluecrab.info/lifecycle.html
http://www.afsc.noaa.gov/Kodiak/shellfish/rkclifestages.htm

 

[Tennyson]

Wow, thanks for all the info! its all clear to me now! thanks

 

[Tennyson]

oh yeah, are these reef safe? I had this crab before I had corals, now I have corals and am thinking about getting another if I can find it.

 

[LeslieH]

Yes, they're reef safe. Some will scavenge if there's something dead but they won't be the cause of anything dying. Keep in mind that they typically live in burrows on beaches & mud flats & spend half the day out of the water. Their respiratory systems are different from other crabs and won't do well with full immersion.

 

[Tennyson]

OK, maybe I won't get one if they will eventually die. Thanks for all the info!

 

[NirvanaFan]

I take it grapsids have eyes that are very short while ocyopodids have longer/taller eyes?

 

[LeslieH]

Yup. In one genus Macrophthalamus (see the Guam web page I linked above) the eyes are on extremely long eyestalks. Also, in fiddler crabs males have 1 huge claw - very distinctive.

 

[NirvanaFan]

I see. Thanks for the clarification and education. I always like to learn more about them.

 

[Grunt]

Ghost crabs usually live in surf zones. I'm not sure you can keep them alive in tanks for long periods of time. Never tried though myself.