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A strange-looking translucent, gelatinous fish with an unusual suction cup on its abdomen made a surprise appearance to a group of scientists studying the deep sea near Alaska.
The strange animal is a spotted snail (Crystallichthys cyclospilus), a seafloor-dwelling creature that lives exclusively in the North Pacific Ocean and can survive more than 2,723 feet (830 meters) below the ocean’s surface. Researchers from the National Oceanic and Atmospheric Administration (NOAA) came across this thick freak while trawling off the coast of Alaska’s Aleutian Islands as part of a routine survey of the deep-sea ecosystem there. On June 19, NOAA scientist and expedition crew member Sarah Friedman shared a photo of a spotted snail on Twitter (opens in new tab).
The fish’s body is “very gelatinous” and feels like “holding a lump of jelly,” Friedman told Live Science in an email. “This is thought to be an adaptation to maintain neutral buoyancy and swim efficiently while dealing with the crushing pressure of the deep sea,” she added.
The team was excited to show the special specimen online so more people could see the fish for themselves. “They live in relatively remote places and at greater depths, so the average person will never encounter this species,” Friedman said. But although such fish are unusual, the researchers found “four or five” different spotted snail specimens during the trip, she added.
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Spotted snails have bodies that are almost entirely transparent—except for the eyes, stomachs, and dark spots on the skin. This adaptation helps them stay hidden from predators. “Many animals that live in deeper ocean depths are translucent,” Friedman said. This allows them to “blend into the dark background in a habitat with limited light availability and few structures to hide behind.”
Like several other species of snails, spotted snails have modified fins on their abdomens that form a suction cup. “This allows them to easily attach themselves to rocks and corals on the ocean floor and avoid expending energy to continuously swim around, especially in strong currents,” Friedman said.
In general, little is known about what these snails do in the deep ocean. “Snails are an incredibly enigmatic and diverse group of fish, with species that inhabit a wide range of environments, from ponds to the deepest trenches of the ocean,” Friedman said. “But not much is known about the ecology of the deeper snail species,” although scientists know they prey on small invertebrates that crawl along the sea floor, she added. (There are more than 400 species of snails worldwide.)
The team also discovered a number of other interesting marine specimens during the trip, including a giant sea spider (which isn’t actually a real spider); a devilfish with massive pointed teeth and a glowing spike to lure prey; and a barrel fish that can roll its eyes at peek through the top of his translucent head.
However, the main purpose of these trawls is not to find rare species. Rather, the surveys are conducted to assess the overall health of the ecosystem, particularly with respect to populations of commercially targeted species. “This research is essential to the sustainable management of the fish and crab species that support Alaska’s commercial, recreational and subsistence fisheries and coastal communities,” Friedman said.
Originally published on Live Science.