I didn’t expect to write so much about jelly blobs, but they’re common on beach walks and the mystery of what each is when alive fascinates me. (Here are links to my earlier blogs about not all beach blobs being jellies and more jelly blobs). Because I seldom find the entire animal, I must do some detecting and use the clues at my feet to figure out what I’m seeing. The latest gelatinous bits showed up in late summer and have continued to wash onto the beach (mostly Monterey’s Del Monte Beach). The mystery — what are they?
These blobs are unusual in that they’re not loose jelly. They have substance, like silicone, and structure, like the petals of a gel flower. At first I thought they were human-made refuse (common on our beaches, too), but as I encountered more over the weeks, I began to think their origin was organic. Yet the shape and structure were foreign to me and the clues as to the creature were minimal.
Then I happened upon a few that were more than just flowerlike cups — they had flaps with color. Helpful clues. The flaps were more jelly-esque and the color was brownish. I started to conclude that I was seeing some part of a jelly (jellyfish). But which part? And which animal? A golden-brown jelly common in Monterey Bay is the sea nettle (Chrysaora fuscescens). Could that be the source?
The “true” jelly (class Scyphozoa) appears to be mostly bell, arms and tentacles. On the beach, I usually find bits of bell. However, there’s much more to a jelly. As hard as it is to imagine, jellies have senses, muscles and a digestive system.
They’re adept predators. Once prey are zapped by tentacles covered in nematocysts (stinging cells), the jelly digests and absorbs the nutrients for distribution to the rest of the body. The body of the sea nettle has frilly oral arms, which transport food toward a mouth inside the center of the bell, or if the food is too large, the arms digest it and transport the nutrients. Such a jelly has an amazing digestive (gastrovascular) system for catching and distributing necessary nutrients.
I think what I’m looking at is the central stomach structure (manubrium) from inside the bell that’s connected to the oral arms. Because of the color of what’s tossed on the beach, I’m guessing these are manubria from sea nettles. But, I could be totally wrong. I’m not a jelly morphologist and interpreting clues doesn’t always lead to a correct conclusion. If any marine gelatinous-life experts read this, I’d love to hear what you think these are. (Thanks.)
Update 12/22/13: Today I took this photo of a mostly intact moon jelly (Aurelia sp.) on Monterey State Beach. This animal is upside-down (top of bell on sand with underside up). You can (at least I can) clearly see the parts that hang under the bell and include the mouth area and manubrium structure. This looks very much like the mystery structures that I’ve been finding on the beach. Mystery solved!
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