nemertinator

In case anyone still is tracking this... This looks like a version of Balionemertes Sundberg et al 2002, a paleonemertean described from the Great Barrier Reef. I found something very similar to be common in Moorea but the base color was more brownish. The "black and white" worm in the Caribbean probably was a Baseodiscus, in a different Order (Heteronemertea) but also a nemertean.

Trolling the site for first time in months... I have to check why I didn't get notified on this response. It has two ventral stripes.

Hi Leslie, I was on the road chasing interstitial nemerteans and must have deleted this post in my rush to get through email. M. rubramaculosa is a good guess. Meg agrees, though it seems to be bigger than any we found in rubble. We would be interested in the size - turtle grass generally is about 5mm or more wide? Many of the burrowing nemerteans can regenerate both head and tail on a midbody piece as long as both of the lateral nerve cords are present, but a head has the greatest potential for successfully regenerating the missing body. Interesting observation about the fish pecking at it, because most nemerteans are chemically defended and very distasteful to potential predators. If this had been non-defended it probably would have been swallowed instantly. However, that doesn't mean that a fish can't do some serious damage while trying to figure out if the worm can be eaten. Of course, a few bottom-feeding fish have overcome the taste problem and do eat the worms. Some of the worms most susceptible to predation break spontaneously into many pieces, each acting like a lizard tail; possibly this gives the head region a greater chance at survival or just allows some fragments to escape rather than giving a fish one easy meal.

It's in the phylum Echiura - spoon worms. The blueish gray part is its so-called proboscis with which it gathers food, mostly microbial and microscopic stuff associated with sediment, which it transports along the hollow, spoon-like part of its proboscis - as you see in the third pic. I've collected other worms in that area for many years and never seen this. Nice pics! If you don't get an ID here and want one, try contacting folks at Smithsonian Marine Station in Fort Pierce, or John Pilger at Agnes Scott College.

Yes, lack of both color or patterning is common for infaunal, sand-burrowing apodous cucumbers. This looks like a synaptid. It looks preserved, certainly contracted. Many synaptids are at least translucent when alive. Difficult to put an ID on these after preservation, though options for the habitat and region probably are not many. Sorry, but I don't know their detailed taxonomy. Gustav Paulay probably could tell you.

Since it hasn't changed length, I would now be inclined toward this crab having a strangle-hold on a gastropod siphon. --Jon

Leslie mentioned the only two options I can imagine. I am inclined to think sipunculan because it's a bit more wrinkled than I would expect for a gastropod siphon, but that's a guess and I'm not very familiar with gastropod siphons. --Jon

Thanks for additional information. No, it's not very rare; but rarely seen in nature. It and most other nemerteans can squeeze into holes and crevices much smaller than their "resting" diameter, and they do and seem to spend most of their time hidden but come out to forage or when their habitat is disturbed. So, I collect them mostly by placing rubble in a tank or tub and waiting for them to crawl out. Tubulanus rhabdotus is common in tidal and shallow reef rubble in South Florida between Ft. Pierce and Miami and has been reported from Brazil, but I've only ever found one along the Belize reef in many weeks of intensive collecting over a lot of years. That's a big geographic gap. However, I think the one in Brazil may not be the same species as in Florida. The St Vincent worm is a very good match for the Florida worm, so I am glad to know of it's record. Best, --Jon

No, for the Nemertinator... Tubulanus rhabdotus (Nemertea), nothing specific known about feeding but probably a predator and scavenger. Perfect desription of its head movement. However, skin is fully ciliated but covered in mucus that it probably makes sticky when handled. What is location of find please? Any data on size? Thanks.

Sorry to be slow on this - just cleaning out old mail. I would not have guessed echiuran proboscis on my own , but yes that is clearly what it must be. Definitely not nemertean

I've been impressed with and puzzled over the similarity between some banded nemerteans, like Baseodiscus mexicanus, and certain brittle stars and eunicids found in the same habitat, and wondered who is mimicking whom. The resemblance between the arms of this octopus and at least one Notospermus (nemertean) known from the IndoPacific is good. The similarity to B. mexicanus is even more impressive, but at present that species is only known from eastern tropical Pacific shores. Nature is sooo much fun!:-) Thanks for alerting us to this cool octopus!

Correct on sp ID. Nice pics!:-)

Wow! Another fine example of why Leslie is the Queen of critter IDs I have seen plenty of solenogastres but would never have guessed this one from the relatively low-res pic. However, in hind-sight, the bulbous shape of the front region makes her call highly probable.

Very nice pic. Snail with hydroid colony (Hydractinia?).

It looks like the head is on left. My non-scientifically studied impression is that many of these relatively long nemerteans forage from hiding places, such as crevices, by exploring as far as they can with the head but leaving the tail end in the crevice in case the worm has to make a speedy retreat. In fact, if you can snag one of these worms it's kind of like pulling taffy, but it often is very difficult to get the back end out of its purchase.