[Coral-List] Soft corals and benthic ctenophores
tomascik at novuscom.net
tomascik at novuscom.net
Wed May 15 18:03:52 UTC 2019
Hi everyone,
I would like to reach out to our soft coral research colleagues to
find out if anyone is (or was) working on benthic ctenophores
ectosymbionts (e.g., Class: Tentaculata; Order: Platyctenida; Family
Coeloplanidae; Coeloplana spp.) associated with soft corals (Order:
Alcyonacea) belonging to the Family Alcyoniidae.
My interest in this was recently awakened when I came across a recent
paper by Glynn et al 2018 [Benthic ctenophores (Platyctenida:
Coeloplanidae) in South Florida: predator-prey interactions. Inv Biol
137(2): 133-150] which prompted me to dig out an old video footage
that was taken on coral reefs in the Banda Sea (Indonesia) some 26
years ago, while working on The Ecology of the Indonesian Seas. I
still recall my excitement when during one night dive we observed long
sticky strands steaming from soft corals. These strands were streaming
mainly from Sinularia spp. in reef areas with strong currents
(0.5.m/sec). The sticky strands were extended from the surface of the
soft corals and then reeled in once plankton and other suspended
material became attached to them. I tried to take video footage of
this activity and succeeded to some extent, but due to strong currents
and high density of soft corals (thus hard to grab onto something
solid) it was difficult to do a good job with close-ups. Looking at
the surface of the soft corals we thought that the sticky strands were
emerging from pores on the corals capitulum. I have done thousands
of dives, but I have never seen this type of feeding activity
associated with Sinularia spp. during daylight hours. Initially I
thought that these strands originate from the soft corals themselves,
but I think that they are actually the feeding tentacles of benthic
ctenophores that may be associated with some of these soft corals.
Looking and the video of this activity it makes me wonder to what
extent is this feeding activity also contributing to the nutrition of
the soft coral itself. The sticky strands that are being reeled in are
loaded with numerous particles (consisting of live plankton and other
suspended organic matter) that are attached to them and they are being
reeled in to the soft corals capitulum. Are the soft corals able
somehow to utilize some of this food source via heterotrophy? Its
been demonstrated that one feeding mechanism that corals deploy to
capture food is through mucus secretion [Brown & Bythell, 2005.
Perspectives on mucus secretion in reef corals. MEPS 296: 291-309].
Could the mucus secreted by soft corals, and then ingested, catch some
of the food particles that are reeled in by the ectosymbionts?
I would like to find out if anyone else has observed this during their
field observations and if they know which species of ctenophores were
involved. If anyone would like to see a short video of this activity
please visit:
https://www.researchgate.net/post/Are_the_streaming_strands_in_the_attached_video_Coeloplana_spp_feeding_tentacles
or
https://www.researchgate.net/publication/301883390_Chapter_Eight_Non-Scleractinian_Cnidaria
Download the File: Sinularia and Coeloplana.mp4
The video was taken during a night dive in strong currents and with a
JVC mini-VHS camcorder.
Thanks, Tomas
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