What are these clear, nubbly, podlike things that I found on the beach?
February 20, 2017 4:04 PM   Subscribe

On January 28, at Schoolhouse Beach in Bodega Bay, California, I found scores and scores of these odd little things washed up on the beach. Do you know what they are?

As you can gather from the images, these are clear, nubbly, gelatinous blobs, about 1.5 inches long by 1 inch wide, or thereabouts. They have no apparent internal structure, and are pretty clearly mostly composed of water. They are sort of slipper-shaped, so I could easily "wear" them on my fingertips.

I figure they are plant matter, not animal matter, but maybe they are some kind of jellyfish or sea cucumber or something? My best guess is maybe some kind of seaweed or seaweed part. I really have no idea, and am very curious. There were hundreds, if not thousands, of these things on the beach that day.
posted by Dr. Wu to Science & Nature (8 answers total) 9 users marked this as a favorite
Google search brought up salps, though the ones pictured are smooth without the little nubs.

I am not a marine biologist.
posted by bunderful at 4:12 PM on February 20, 2017

posted by deadcrow at 4:42 PM on February 20, 2017

I am a biologist, but not a marine biologist. However, I have taught intro bio for years, and tunicates/salps are important in teaching intro bio (they are in Phylum Chordata along with the vertebrates and are basically the most closely related animal to us that doesn't have a backbone). They definitely look like tunicates for me.
posted by hydropsyche at 5:01 PM on February 20, 2017

Best answer: They are Sea butterflies.

Excerpt from the page:

... It’s not a butterfly, of course; neither is it a jellyfish. It’s a marine snail.

The sea butterfly (Corolla spectabilis) is a gelatinous snail adapted to a pelagic (open water) life. It’s not very big — the body core is about an inch (2.5 cm) and the wings grow to 3 inches (8 cm). They work like wings, flapping to move the animal through the water (as you saw on the video). Also on the video, you may have noticed a dark spot in the animal. That’s its gut. To eat, it creates a mucous sheet, like a drift net, up to 6.5 feet (2 meters) across to collect plankton from the water. This snail has no external shell, but is protected by an internal gelatin core called a pseudoconch (or faux shell) that’s covered with bumps called tubercules...

The pictures within the article are precisely like those you included. The video shows one with its 'wings', swimming around during the author's dive. Gorgeous HD-quality footage, at that.
posted by Amor Bellator at 5:12 PM on February 20, 2017 [21 favorites]

Amor beat me to it, pseudo conches. You see them quite a bit in Monterey to.
posted by fshgrl at 5:20 PM on February 20, 2017 [1 favorite]

Response by poster: Wow. Sea butterflies! Incredible. Thanks, AB!
posted by Dr. Wu at 5:24 PM on February 20, 2017 [2 favorites]

Thanks for asking this question, Dr. Wu! We saw the same thing on a beach in Alaska last summer and have been wondering what they were.
posted by belladonna at 5:27 PM on February 20, 2017

Yep, that's definitely the internal shell from the pteropod Corolla! I used to come across them when I did marine work in Washington state.
posted by cyclopticgaze at 5:38 AM on February 21, 2017 [1 favorite]

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