Benthic Comb Jellies!! New Observations?

This image by Nick Hobgood via Wikipedia

Last week, I had a pretty fun conversation with some colleagues, namely Anna and Ned deLoach at Blennywatcher.com, about benthic comb jellies and Its been awhile since I've had a chance to play "lets run through Flickr and see if we can discover anything new", so I thought I'd try my luck this week again !!

What are benthic ctenophores (aka benthic comb jellies)? I've explained them before in one of my earlier posts (here), but simply put, they are an unusual group of comb jellies, which you might be more familiar with as purely pelagic or swimming animals, such as this "sea gooseberry"

They swim with the shimmering paddles you see in the video and feed using those long tentacles as they are dragged through the water behind it...

Benthic ctenophores (aka bottom-living comb jellies, benthic comb jellies, sessile comb jellies) are basically the same idea except that the animals live on bottom substrates. They occur in tropical habitats and in shallow to deep-water settings.

Here's a nice pic of a species which lives on coral (image by Ria Tan and my friends over at Wild Singapore). You can see the tentacles doing the same thing..but oriented "upwards" away from the bottom.. and into the current.
                
In the last few years with the proliferation of video and underwater cameras, we've been seeing more and more of them. And so, learning more and MORE about them!!

Anna and Ned over at Blennywatcher.com for example were very lucky in that they were able to capture one such animal FEEDING for the first time ever!! (Here) 

 One of the main reasons, I got so interested in benthic ctenophores was that they live primarily on a starfish, Echinaster luzonicus, a 6-7 rayed species frequently encountered throughout the Indo-Pacific.

The ctenophore species is presumably Coeloplana astricola (no specimens examined, so hence my caution). As you can see in the picture above.. the feeding tentacles project up into the water to feed as they do in other species..
                  
Based on this cool video made by blennywatcher.com, there appear to be different species of benthic ctenophores present on each individual host. But usually not more than one species per host...

Other hosts? Interestingly, a review of images on Flickr reveals at least ONE other sea star that serves as a host for Coeloplana.., Another species in the SAME genus as E. luzonicus.

This one is called Echinaster callosus. A weird but colorful starfish with big puffy protrusions on its body surface...

Here is one of the benthic ctenophores of the surface with its feeding tentacles extended...

If I cheat a bit and go outside of Flickr I find that benthic ctenophores also live on the bright blue Linckia laevigata (here)

A species of what looks like Pentaceraster...(here)

Are these new records of hosts? I couldn't find these in my brief review of the literature, but I'm not a benthic ctenophore expert....

How Far Can they GO?  Another question we always ask when we see stuff like this, is just how MANY of these ctenophores can "pile on" to a host starfish??

This looks like a LOT. At least 20 to 30!! Nearly covering the surface of the starfish..

One with 20-30...

Another one mobbed by benthic ctenophores! 

and GREAT scott! this one is almost completely covered by them. By my count? About 40 to 60 of them.. but the outlines of each ctenophore are hard to make out...

and more..and MORE! 

Here's one with 4 arms being regrown also completely MOBBED by these ctneophores.. covering the surface

Some individuals of E. luzonicus end up being practically a hotel for commensals! This one not only has the benthic ctenophores but some polychaete worms as well...

Getting away from the benthic ctenos that live on sea stars, there's also been some cool observations of some others from Flickr and Twitter..

Here's an unidentified Indonesian benthic ctenophore with its feeding tentacles out.. and maybe its caught something (a shrimp)? or perhaps its just the confluence of feeding tentacles..

From my colleagues in South Africa are a bunch of images via Twitter of something similar to Lyrocteis, a larger "bunny eared" benthic ctenophore from about 100 m off the coast of Natal...

Some of these are just unearthly..

Deep reef invertebrates by @RyanFarmy1 @ACEP_ZA like this benthic ctenophore (comb jelly) http://t.co/6LUl5Ezm5k pic.twitter.com/Swv4vFeAWt

— SeaKeys (@SeaKeysSA) August 22, 2014

Benthic ctenophore (comb jelly) near Aliwal shoal KZN seen with ROV. pic.twitter.com/jBgKuTMjhL

— ACEP (@ACEP_ZA) June 2, 2014

and finally, from my friends at the California Academy of Sciences (Steinhart Aquarium) the curator of the "living collection" Bart Shepherd tweeted these 

Wow! RT @SteinhartBart: Benthic ctenophore I collected @300' has its feeding tentacles out #CASfieldnotes pic.twitter.com/RqZvMQ4d0e

— MBARI (@MBARI_News) May 12, 2015

weird and wonderful animal: Lyrocteis- a benthic #ctenophore that I collected at 85m on recent @calacademy expedition pic.twitter.com/1MnD3KXbLV

— Bart Shepherd (@SteinhartBart) May 1, 2015

Benthic Ctenophore Video Watch!

Photo by Arne Kuilman

This is one of those RARELY seen animals that I love sharing with people because they are SO strange.

First lesson: Ctenophores are a group similar in appearance to jellyfish. But in a separate phylum-The Ctenophora. Here's the Wikipedia for handy-dandy quick reference. They are identified by "ctene rows" that are what they use to propel themselves. Underlight these ctene rows shimmer giving them an iridescent appearance which looks like this:

But there's one subgrouping of comb jellies that, for some odd reason, have taken to living on the sea bottom-sometimes on other animals, such as sea stars but also on sea urchins and corals.

Its thought that these are commensal relationships. In other words, the ctenophores live at no apparent "cost" to the host. But relationships are poorly understood-so who knows?  

At the very least having THAT many ctenophores crawling around on your surface might clog up your papulae for respiration and so forth.

A brief explanation was from my blog awhile back here.  I don't know how common it is to see these in the field but these are pretty rarely seen for most people (although here is a small group on Flickr devoted to them) .. so I thought it would be a good idea to put them all in one place for everyone to enjoy (especially since there's a couple of new ones!)

Enjoy! 

The animals are those strange moving white blobs on the surface. The ones living on the sea stars are in the genus Coeloplana. I'm not sure if the ones further down that are not living on sea stars are the same genus.. but I'm guessing probably not.

Those threads? Are the feeding tentacles that you would normally see here in the "sea gooseberry" Pleurobrachia

But here is Some neat NEW Benthic Ctenophores on Echinaster callosus! Shot in Lembeh

here is the FIRST video of benthic ctenophores as shot by Blenny Watcher. Host is Echinaster luzonicus

Here are some from Bocas Del Toro, Panama without the sea star host. Shot by Rosana Rocha

Here's are more species from Japan!!