please ID this moving blob

Looks like a nudibranch to me. Some are preditory, so I would take it out while you still see it, just to be sure.

What would the predatory nudi's feast on? Unfortunately I wouldn't be able to take it out because iton the rock at the very bottom of my structure which is covered by xenia.
 
The preditory nudis often go after corals, like zoas. If its a flatworm, I've never seen one like that before. That thing is huge!! Either way, get it out.
 
I had 2 that appear exactly the same as yours its a predatory flatworm. one of mine was 4" or so and the other just under 3" ill try to find some info for you.
 
That is a flat worm, prob one of the worst hitch hikers i have ever experienced.

What made this thing the worst hitch hiker? I've never seen this guy before and its not really eating any of my fish or corals.

I would also like to ask, where the hell did this thing come from? I've had this tank for almost 3 years and have never seen it during the day or night. Do these worms come on corals because I started my tank out with all base rock that didn't have any growth on it.
 
Last edited:
I am sure this pair that i had were the cause of me losing quite a few clams, countless snails and a group of hermits. Basically lots of money down the drain from them... I got lucky one night and spotted the big one. It took a long time though for me to catch them both because as soon as they would see light they would scoot to the hardest to reach spots.
 
I am sure this pair that i had were the cause of me losing quite a few clams, countless snails and a group of hermits. Basically lots of money down the drain from them... I got lucky one night and spotted the big one. It took a long time though for me to catch them both because as soon as they would see light they would scoot to the hardest to reach spots.

That's crazy, where does such a flat piece of **** hold any of its food? Anyways you mentioned it ate your snails and now that I think about it, once every few months I will notice an empty turbo snail shell. The snail was always fine the day before and then it would just be the shell. I would always blame the serpent stars because I always saw them mounting the shells and wrapping their tentacles around the whole snail as to pry it out of the shell. But until now I didn't realize that it was probably that stupid flat *** worm coming out conviniently at night to kill them. I should just never turn the tank lights off that way the worm will just never get to come out and eat, lol.
 
Something i also found interesting was a few times I witnessed this thing go into rock crevices that my smaller fish slept in at night, such as my mandarin and 6 line wrase.. My mandarin vanished without a trace, always made me wonder if the worm had something to do with it but who knows..
 
From genus "Platyhelminthes" aka flatworms!
That is a flatworm: simple bilateral symmetry, they move using cilia and mucous on their ventral surface.
There are free-living flatworms and parasitic flatworms.
This appears to be a free-living flatworm. These guys feed on dead or slow-moving organisms (this may include sleeping fish!). The worm will engulf its food and then a pharynx will fold out from its ventral (bottom) surface, ejecting enzymes which begin digestion. The food is sucked into the body via pharynx into a simple digestive tract. This worm is lacking eyespots and aurelia (plural: auricles), so it is not a planarian.
From what I can gather from my marine biology knowledge, this is a free living flatworm (Phylum Platyhelminthes) which is NOT a planaria.
Get that thing out of your aquarium asap.

Too much information? :)
 
Last edited:
It's a polyclad flatworm (some of which do have eyes), quite likely to be a species of Pericelis.
Image14.html

http://www.flmnh.ufl.edu/reefs/guamimg/platyhelminth/Pages/Image14.html

They're well known mollusc predators. Being so flat they can easily slip into the narrowest cracks in rocks or under the sand. The gut is highly-branched & extends throughout the body. Some are general feeders but others are quite specialized & will only prey on certain sea squirts or sponges, etc. Pericelis prefers molluscs above all. Small snails or clams they will swallow whole, digest the flesh, then spit out the shell. For big ones - even giant clams - they will do as Scuba-Al said: extrude their pharynxes, eject digestive enzymes, then slurp up the partially dissolved flesh. Flatworms can go a long time without eating. They start shrinking as they utilize the nutrients already in their tissue. I suspect these Pericelis will eat detritus & other small animals in addition to molluscs, allowing them to survive in tanks for months after all the snails & clams are gone.
 
Back
Top