This Two-Inch Tunicate Salp Is a Swimming Smorgasbord

"The Tunicate salp, commonly referred to as a salp, looks a bit like an elongated jellyfish-minus the tentacles. These barrel-shaped creatures fall into a category of marine animals called sea squirts, which are, believe it or not, actually taxonomically closer to humans than they are to jellyfish. That's because, despite their gelatinous-looking forms, they're actually invertebrates with a kind of spine, known as a notochord, that runs down their back and anchors muscles."

"It's a puzzle trying to understand what parts of the salp are its body and which are its prey, as its remarkably transparent flesh allows us to see everything at once. But upon closer inspection, a yellow blob looks suspiciously like a small fish, and it appears that a few larval crabs and shrimps are along for the ride. Salps typically eat phytoplankton, but they'll essentially ingest anything that gets trapped in a meshy feeding net."

"On a dive off the coast of Indonesia, photographer Massimo Giorgetta encountered one about two inches long that had recently enjoyed a bit of a buffet. The image recently took the bronze award in the Nature/Underwater category of the Tokyo Foto Awards. "Inside the Tunicate salp is a box fish in juvenile form, some very small flatworms in juvenile form, then some larval Squilla mantis, some heteropods, and several animals that I cannot determine," Giorgetta says."

Tunicate salps are barrel-shaped, transparent sea squirts with a notochord that anchors muscles, placing them taxonomically closer to vertebrates than to jellyfish. Sizes range from fractions of an inch to over a foot. Salps feed by filtering water through a meshy feeding net and typically consume phytoplankton but will ingest anything trapped, including small animals. A two-inch specimen observed off Indonesia contained a visibly ingested juvenile box fish along with larval crabs, shrimps, small flatworms, Squilla mantis larvae, and heteropods, illustrating broad and opportunistic feeding habits.

Read at Colossal