[NatureNS] re sea gooseberry -- was ??Arctic Comb Jelly

Date: Thu, 09 May 2013 14:24:44 -0300
From: "Stephen R. Shaw" <srshaw@dal.ca>
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Several of these ctenophores washed up alive on Martinique Beach when  
we were there about a week ago. This type, Pleurobrachia according to  
Jim, does not have tentacles and most of them don't sting (a few  
larger types eat jellyfish and will re-use their stinging cells).  The  
shiny things that refract the light are eight rows of long cilia on  
the sides which beat in a rhythmic wave-like progression (metachronal  
wave), and are the means by which the animal swims, rights itself, and  
moves towards prey -- the ciliary wave can reverse direction.

As a perhaps interesting (?) side-commentary on how science is  
(sometimes) done and which takes me back a while, my old boss  
published a fairly high profile paper in the journal 'Nature' years  
ago that claimed to have recorded electrical waves from the ciliary  
bands in a comb jelly, made while working in Naples, Italy. These  
electrical waves supposedly formed the neural basis for the ciliary  
rhythm.  The microelectrodes used possess a very large 'tip potential'  
though, which can be modulated if the tip is mechanically distorted by  
striking something.  A bit later, a colleague and I (then junior  
upstarts) spent an afternoon in Scotland working on the large  
ctenophore Beroe and were able to convince ourselves that the  
published effect was caused by the microelectrode tip being struck  
mechanically during the metachronal waves from the cilia. The effect  
was simply an electrical artefact from microelectrodes that never even  
entered the cells. I don't think the original claim was ever retracted  
but the main US expert in the field of ciliary control at the time  
didn't believe it anyway: the wave is believed to be conducted along  
the ciliated band by viscous (mechanical) coupling between the cilia,  
not by an underlying neural-electrical wave that coordinates the  
ciliated cells.
Steve (Halifax)

Quoting duartess@ns.sympatico.ca:
> just wondering though, do those tentacles sting folks who might be  
> swimming where they are occurring?
> Thank you
>
> Gayle MacLean
> Dartmouth
>
>
> ---- Tom & Terri <terri.crane@ns.sympatico.ca> wrote:
>> Paul and All
>>
>> I've always heard and refer to them as "Grape Jellies". They  
>> resemble a skinned grape was the reason I was told as a inquisitive  
>> child ant to me it made since. Thus the name stuck. Most of the  
>> fishing community that I know in eastern NS and eastern PEI all  
>> have the same name for the collective group of these cold water  
>> Jelly Fish.
>>
>> Tom Kavanaugh
>>
>> Canso
>>
>>
>>   ----- Original Message -----
>>   From: James W. Wolford
>>   To: naturens@chebucto.ns.ca
>>   Sent: Wednesday, May 08, 2013 8:12 PM
>>   Subject: [NatureNS] re sea gooseberry -- was ??Arctic Comb Jelly
>>
>>
>>   Paul and all, I think your nice photo is of what most Maritimers  
>> call "sea gooseberries" -- you were correct in calling it a comb  
>> jelly (Ctenophora phylum), but the Latinized name, I think, is  
>> still Pleurobrachia pileus.
>>
>>
>>   Mertensia ovum is a new name for Beroe ovum, which is a comb  
>> jelly, all right, but is a different one from our common "sea  
>> gooseberry"; also Paul's site did not mention phylum Ctenophora for  
>> comb jellies, which are distant cousins of jellyfish, sea anemones,  
>> & corals).
>>
>>
>>    I Googled "sea gooseberry" and got:
>>
>>
>>   Sea Gooseberry - Pleurobrachia pileus - Seawater.no
>>
>>   www.seawater.no/fauna/ctenophora/pileus.html - Cached
>>   16 Mar 2013 ... Kingdom: Animalia; Phylum: Ctenophora; Class:  
>> Tentaculata; Order: Cydippida; Family: Pleurobrachiidae; Scientific  
>> name: Pleurobrachia ...
>>
>>
>>   Cheers from Jim, still in B.C. but on my way home.....
>>   ---------------------------
>>
>>
>>   On 8-May-13, at 7:12 PM, Paul L wrote:
>>
>>
>>     Saw many Arctic Comb Jelly's today at the Bedford waterfront,  
>> they are about 2-4cm and looked bioluminescent (or cilia refracted  
>> the sun?).
>>
>>     Not sure of the identification, here's a decent close up photo  
>> of a few of them:
>>     http://www.wildlifesightings.net/temp/ArcticCombJellyAquatic.html
>>
>>
>>
>>     Paul Lindgreen
>>     Wildlife Sightings http://www.WildlifeSightings.net
>>     Contribute nature sightings and be part of citizen science


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