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Saturday, August 12, 2017

Deep-sea highlights

It was hard to choose among the many photos from the E/V Nautilus dive at Bodega Canyon yesterday (11 August 2017).  Here are a few of our favorite screenshots.  [Click on the images for larger versions.]

Crinoid, or feather star, probably Florometra serratissima

Deep-sea nudibranch, Tritonia tetraquetra

Although Tritonia seems to have been the most common nudibranch species observed on these dives, a few other species have appeared.  

Finding the nudibranch in the next image is harder.  The ROV was focused on the primnoid coral (see white branches at right side of photo) covered by beige and yellow zoanthids (the dominant animals in the image).  But look for the small white nudibranch in the upper left corner! 

[In case you're wondering, zoanthids are cnidarians with features similar to corals and anemones, but they don't have hard skeletons and their tentacle arrangement is different from most anemones.]

The views of deep-sea bamboo corals were spectacular:

Bamboo corals are in the family Isididae.  I'm just learning about these corals, but I think the individuals pictured here might be in the genus Keratoisis.  Although bamboo corals are named after their beautiful skeletons with a banding pattern similar to bamboos, it was fun to see these living corals, with their dense peach-colored polyps:

The next coral species is Isidella tentacula.  The "tentacula" part of the name comes from their distinctive 'sweeper tentacles.'  Look for them at the base of coral:

Here's a close-up of the sweeper tentacles near the holdfast of the coral (see below).  It's thought that these tentacles are defensive, containing concentrations of stinging nematocysts.

Many thanks again to the E/V Nautilus crew for sharing these wonderful deep-sea communities with us.  It's been a gift to join you in exploring Bodega Canyon!

P.S.  We hope you get in at least one more dive before you head north.  And if you happen to see this post, we'd love a few more close-up views of a stalked crinoid (sea lily).  :)


Hollis said...

Thanks so much for sharing these marvelous screen shots and providing some information about these fascinating animals. While watching, I kept wishing they would just hang out for a while so we could look at them more closely & your screenshots allow for that. Any ideas about the little pink critter on the tip of the feather star?

Jackie Sones said...

Hi, Hollis! My instinct is also to linger and look around.

It's interesting that you are asking about the little red/pink coral that's growing near the tip of the feather star. (The coral is attached to the bottom and growing upright.) The ROV was actually trying to get a better look at the coral, but in doing so they provided a very nice view of the feather star. We were excited about this close-up because in general the ROV didn't pause on echinoderms very often.

Darris said...

Like Hollis, I so appreciate the still shots and explanations you posted here . . . I love the color of the bamboo coral and intend to get the paint store to mix up a color closest to this for my next paint project ; )