Nudibranch or Cucumber? Nudibranch: Likely Tritoniid – 9/22/09
Hello Crew!
<Hello, Tim!>
Can you identify this marine invertebrate for me please?
<I’ll sure try!>
It was a hitchhiker on my liverock. I’m not sure if it’s a Nudibranch or a cucumber.
<It looks like a neat little Nudibranch rather than a Cuke/Holothuroid but I can certainly understand the confusion. Both have species with similar body shapes and branched structures around the head/mouth. In the case of Holothuroids, those structures are actually branched oral tentacles used for feeding, and typically number anywhere from 10-30. In comparison, Nudibranchs have oral tentacles along with two “antennae” called rhinophores. Both tentacles and rhinophores can range in appearance from simple to highly branched/ornate. I think what you have is a Nudibranch in the suborder Dendronotina, family Tritoniidae. Tritoniids feed on soft corals (especially Xenia), so if you have any in your system, I’d remove this little guy. If you’d like to pursue this ID further, please see the following link for a list of species in the above-mentioned family (each is a link with more information/photos): http://www.seaslugforum.net/specieslist.cfm
Start with the genera Marionia and Tritonia. The genus Marionopsis is also a possibility, but not listed (try a Google or other search engine). You might also want to check the family Bornellidae as well (at the above link). There are some similarities around the head but the structures (“cerata”) running along either side (down the back) tend to be simpler in shape (less delicate and finely branched).>
Thank you for the help in advance,
<You’re very welcome – that’s a neat little critter!>
Tim
<Take care, LynnZ>

Hitchhiker ID: Rock-Dwelling Sea Cucumber – 6/17/09
Hi again,
<Hello Elfrieda, Lynn here today.>
Another puzzler for me....6 months into the set-up of my 24gal Aquapod w/ metal halide light. It appears to be some sort of worm perhaps???
<Actually, what you’re seeing is the feeding apparatus of a rock-dwelling sea cucumber/holothuroid. For more information, please start with the FAQ’s titled ”Please help to ID: Sea Cucumber – 6/1/09” and “Anemone Id? Nope, It’s A Cuke! 8/10/07”, located at the following link: http://www.wetwebmedia.com/cukeidfaqs.htm . Please also note links within the two FAQ’s.>
The second time I've seen it on the same rock....and the last picture is just before it disappeared.
<Nice photos!>
Thanks so very much for your time.
<You’re very welcome>
Elfrieda
<Take care, LynnZ>

Re: Hitchhiker ID: Rock-Dwelling Sea Cucumber – 6/17/09
<Hi Elfrieda>
Another look at this stranger....
<Neat!>
Its tentacles appear to be catching food and one by one are drawn into its 'mouth'.
<Good observations - that’s exactly what it’s doing!>
Thanks again,
<You’re very welcome>
Elfrieda
<Take care, LynnZ>
<<A nice short video clip... that RMF doesn't know how to add to WWM...>>