Giant Keyhole Limpet

[nkw5]

My buddy and I saw this unusual creature at Santa Cruz Island, one of the northern Channel Islands off the coast of Santa Barbara, CA, which we believe is a giant keyhole limpet. I can't find anything on the internet that would help me understand what we caught on film since keyhole limpets usually look like rocks. Can anyone tell me what's going on here? Did the limpet turn inside out?

 

[RyanT]

What you have is definitely not a keyhole limpet. The hole in the top of the limpet shell is modified for waste disposal, the animal cannot squeeze itself through the hole. I'm not certain, but I think what you've got here is some type of sea hare. You can definitely see what appears to be the molluscan foot that it is crawling on and the portion on top looks like the mollusk's mantle.

 

[drbill]

Looks to be the right size for Megathura crenulata although the coloration and body are certainly unusual. If indeed it is one, the mantle has been wrapped around the somewhat small shell. Almost looks like one on top of the other though.

See my Dive Dry with Dr. Bill columns:

http://www.starthrower.org/products/DDDB/DDDB_050-099/DDDB_084 giant keyhole limpet.htm

http://www.starthrower.org/products/DDDB/DDDB_550-599/DDDB_591 giant keyhole limpet.htm

 

[RyanT]

Thanks Bill, perhaps it is a keyhole limpet. I've just never seen one with the mantle completely covering the shell. If this is a keyhole limpet, indeed it looks like one on top of the other. Either way, it didn't invert itself through the hole.