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Sponges at cove 2
Posted: Sat Jan 02, 2016 10:53 am
by luv2dive
I found these sponges at Cove 2 in a jack straw by the honey bear.
Any idea what these are??
Re: Sponges at cove 2
Posted: Tue Jan 05, 2016 6:42 am
by Tidepool Geek
Greetings,
With a few exceptions, sponges are all but impossible to identify in the field and working from a photo is even less likely to be accurate.
That said, I'm not sure that this actually
is a sponge. Sponges are characterized by (among other things) a huge number of water intake holes called 'ostia' (which may be too small to see without magnification) and a smaller number of water outlet holes called 'oscula' that should be large enough to see unaided - Maybe it's just old eyes but I couldn't see any obvious oscula in the photos.
What it looks like to me is a compound tunicate - possibly the invasive species
Didemnum vexillum. More info on this species (including how to report sightings) can be found here:
http://wdfw.wa.gov/ais/didemnum_vexillum/
Tunicates are characterized by having two siphons per animal although on a compound tunicate these may require magnification to see.
If you're willing to remove a glove, one way of telling a sponge from a tunicate is touch - a sponge will feel velvety to gritty while a tunicate will feel smooth & slippery.
Invasively yours,
Alex