A Sighting of Ctenophora

At least four little creatures are in this picture

   We were on the south side of Long Porcupine island, headed back to Bar Harbor, when I noticed something iridescent in the water, then something else and another!   Dozens of quarter-sized striped balls with two long tentacles.
   A little ways on, there were more, and then a few of these larger creatures:

 

   We watched and photographed. Through the rest of the trip, we occasionally stopped and searched for more.  There were none close to Bar Harbor, or Bar Island, but most other places we saw them.

  My Mac's Field Guide to Northeast Coastal Invertebrates identified the larger creatures as Northern Comb Jellies and the superball-sized ones as Sea Gooseberries.  Some more research at home would provide some interesting tidbits.

Both Northern Comb Jellies and Sea Gooseberries are Ctenophora.  (Americans get to use CB language to pronounce Ctenophora, "10-o 4-a little rainbow buddy,"  but everyone else has to append a "ka" on the front.) Ctenophora are a separate phylum from jellyfish, (which are cnidarians).  Both ctenophora and cnidarians are simple brainless creatures.  Both are a mass of jelly with cell layers outside and lining the body cavity.  In the ctenophora those layers are two cells thick (versus one for the jellyfish.)

An underwater shot

Ctenophora get their name from their combs (or ctenes.)  These combs are made up of rows of fused cilia, whose movement propels the little creatures.  It is also the movement of cilia which causes their iridescence.

This is blurry but is shows a few flashes of green and blue

Those two strings hanging out from the Sea Gooseberry are not stingers.  Jellyfish may have stingers, but ctenophora do not.  The strings are made up of sticky cells, used to capture prey and drag it to their mouths.  (One end of the body is a mouth, the other an anus.)

These little creatures look harmless, but Ctenophora are voracious carnivores; consuming zooplankton, fish eggs and pretty much anything else they can stuff inside themselves.  They can eat ten times their body weight every day.

One species of ctenophora, the sea walnut or Mnemiopsis, is an invasive species in the Black Sea, destroying the fishing industry there.

Blooms of ctenophora, like jellyfish blooms, can be a sign of an ecosystem out of whack, or they might just indicate favorable conditions for breeding.  Ctenophora reproduce year 'round.

There are about 150 known species of ctenophora, found from arctic to tropic waters.  Many are bioluminescent.

So, those were our new species sighting of the day!  If you'd like to learn more, check out:
 Wikipedia: Centaphora   http://en.wikipedia.org/wiki/Ctenophora
Centophores - some notes from an expert - http://faculty.washington.edu/cemills/Ctenophores.html
Smithsonian Jelly Fish and Comb Jellies  - http://ocean.si.edu/jellyfish-and-comb-jellies

Mark is moving on...