3 Critter questions and then some pics for Leslie!

This guy was hanging onto this slender "thread" about 15cm below a ledge, anyone have an idea what kind of behaviour this is?

I am assuming these are snails. Is there anyway to identify what kind they are and if they are toxic or poisonous?

Last of the critter questions... there is a fine "net" extending out from this trapdoor. What is it?

Finally, the worm picture. This worm was literally reaching out into the current waving his "arms" around looking for something. Just wanted to post a pic of a worm for you Leslie! By the way, my wife found this one and has been looking for worms for you. Hope to get some pics soon!

Leslie,

My wife found this urchin with the madreporite visible. This is the first one we have seen with what appears to be the orofice on the top exposed. Are we right in assuming this is where the seawater passes through to the urchin?

Your bubble shell appears close to Haminoea cymbalum:

http://www.seaslugforum.net/factsheet.cfm?base=hamicymb

The colouration is a bit different, though. In a few weeks when the Sea Slug Forum is once again accepting messages, you may want to send it in to Bill Rudman.

I'll leave the wormie stuff to Leslie!

Cheers,

Marli

Last of the critter questions... there is a fine "net" extending out from this trapdoor. What is it?

That is a Wormsnail. A very unusual snail. The mucus threads are how it collects food.

Leslie,

 

My wife found this urchin with the madreporite visible. This is the first one we have seen with what appears to be the orofice on the top exposed. Are we right in assuming this is where the seawater passes through to the urchin?

 

The bubble looking thing on top is where it poops.

Will's right. I was looking at the wrong picture when I said the sac was the madreporite. They do have madreporites, but the "balloon" is the anal sac. Some urchins have them, others don't. In the ones that do the color is often a character useful for identification.

The worm snails are snails that forgot how to coil into a nice neat shape. Instead, the tubes are long & curvy; in many of them the last bit towards the opening stands up off the rock which creates better micro-currents to bring them food. They produce the mucus strings to catch their food then reel them in, swallow them whole, then start all over again.

The last "worm" is the forked proboscis of an echiuroid. These are called spoon or tongue worms. Tongue worm is obvious but I'm not sure where the name spoon worm comes from. Echiuroids are soft bodied unprotected animals that hide in burrows in the bottom or in rock crevices. The proboscis is extremely stretchy and can extend for several meters in some of the biggest species. The food is moved along by fine hairs called cilia - much like a conveyor belt - to the mouth. When a predator comes by the worm can easily detach the proboscis to detract the predator then grow a new one.

Tell your wife I think she's a splendid person! Probably beautiful and very intelligent, too.

Leslie,

You might like seeing these from the GBR, then:

Terebellid polychaete:

Echiuran proboscis:

AIJ - very nice. I especially like that you just called the first one a terebellid rather than follow the books which unrealistically put species names on pictures of feeding tentacles!

Somehow a "sack of poo" just doesnt sound as cool as madreporite!

why don't shrimp guys (like me) get the same attention as worm girls ???

WHERE ARE ALL THE ODD SHRIMPS ?????????????????????????

PS Leslie: greeting from Sammy, we are both on Utila now

we got somethimg like 15 new species

but more important, I just did my PADI, was about time !

so shrimps are in big trouble now

Silly guy, it's because worm girls are always much cuter than shrimp guys, of course.....

Only 15 new species? Doesn't sound right for a couple of non-stop collectors like you. Are you & Sammy both sick? Too weak to dive? Or too busy fighting over who gets what shrimp?

Congratulations on the PADI! You'll be able to get me much better worms now. I'd be much more worried about you than the shrimp. You - like me - are exactly the type to keep saying "just a few more minutes, a few more shrimp (or worms)" while your air is running out. I hope all your dives are enjoyable, productive, and safe!