Funny looking hitch hiker (Can you ID him)

Josh_22 · #1 04-22-2002, 05:34 PM

Sorry dont have a picture but I do have a discription.

I have had this rock for over a year and last night when i was looking over it I came across and little snail type thing. It has feet like a snail although its shell is formed like turtle. It is no larger then a finger nail. The funny thing is it has a small hole in the top of its shell and when I shun the light on him he sprayed some kind of clear liquid out of this hole.
What is it?????
JOSH

Delphinus · #2 04-22-2002, 06:32 PM

If it looks like a miniature abalone, then my guess is it's a Stomatella sp. snail, which comes in sometimes on rock from Indonesia and vicinity. Awesome little algae grazers, and will multiply in our reef tanks. Do a search on "stomatella" maybe and see if this is what you have. Alternative, I know that TRA Vol I or II has a picture of these guys, check the index if you can get your hands on those books.

The "turtle" shell kind of makes me wonder if it could be something else though... sure you can't get a picture of it? The ones I have in my tank, I wouldn't describe their shell as like a turtle's. More like a small fingernail. I can't see how this shell could possibly shelter these snails, it's way too small for them.

Biogeek · #3 04-22-2002, 10:15 PM

If it wasn't for the hole in the shell, Stomatella would be the most likely guess, but these little guys don't have a hole in the top of the shell. I'll guess that maybe you're seeing a keyhole limpet, but a picture here certainly would help!

A good place to start is usually looking through the Hitch-hikers FAQ and see if you can't find what you're looking for, or at least something that is at least a close approximation...

Rob

djbravoleader · #4 04-23-2002, 11:35 AM

It's a chiton i think, here is a link to check out. If the link does not work for you try to do a search for Chiton on the www.
http://www.animalnetwork.com/fish2/a...wb/default.asp

Josh_22 · #5 04-23-2002, 01:15 PM

You were right its a keyhole limpet. I did a search on google and found a picture. That was him all right. Can anyone tell me if the fluid that he exerts from his back is bad for my aquarium.
JOSH

Biogeek · #6 04-24-2002, 12:30 PM

Josh, there are a couple of things that could have been in the spray you saw coming out of the hole on top of the shell, and neither one of them is anything to worry about.

In order to explain it, I have to give you a little background. Like other snails, these animals are twisted around during development in a process called torsion (there is more info and pictures here if you're interested). This process basically involves one side of the baby snail growing much faster than the other such that the body is twisted around 180 degrees counter-clockwise such that the anus moves into a position directly over the head (making all snails poop-heads ;) ). Different animals deal with this in different ways, but the keyhole limpets use that hole in the top of their shell as a little poop volcano, and eject their wastes through it. They also do the same thing when spawning, so the eruption of clear fluid that you saw could easily have been feces, or gametes.

The other possibility is that the animal was startled when you suddenly shone the light on it, and clamped down hard on the rock, forcing water trapped under the shell (and some debris/detritus that is inevitably trapped beneath it) to be ejected from the hole in the top of the shell.

In either case, it is a harmless part of their normal behaviour and nothing to really worry about.

Rob