See-Through Ocean Animals

From superheroes to myths and legends, humans are fascinated by creatures whose appearance helps them move through the water with stealth. From shape shifters to massive predators, all ocean creatures have abilities that help them navigate the open seas. Meet five incredible see-through animals you can find in our ocean—if you can spot them.

Chirodotid sea cucumber

Sea cucumbers come in a variety of shapes and colors, including a transparent species, the see-through sea cucumber. This chirodotid sea cucumber stands out from the crowd by blending in with its almost completely transparent body.

Not much is known yet about this tiny invertebrate. It was first observed in 2020 during a deep-sea exploration in the Pacific Ocean conducted by the National Oceanic and Atmospheric Administration (NOAA). Scientists hope that more research could reveal it as a new species. It likely feeds off small crustations on the sea floor. Documenting marine life helps people and scientists advocate for policies that keep our deep ocean biodiversity thriving.

Piglet squid – Cranchiidae

The piglet squid is another micro see-through creature that has stolen hearts with its adorable “snout-like” mouth and large cartoonish eyes. Like the sea cucumber, the piglet squid lives in deep waters, at least 2000 fee or more below the surface, and feeds off small crustaceans. The piglet squid has been spotted in the South Pacific, but research is needed to understand more about its habitat and the role it plays within the vast deep-ocean ecosystem.

Crocodile icefish – Channichthyidae

The crocodile icefish stands out even among the see-through crew of the ocean as the fish is the only vertebrate with colorless blood. This 10- to 20-inch predator uses its stealth to ambush its prey. A crocodile icefish will target marine animals up to half its size, attacking with lightning speed and pulling its victims into the cloudy sea floor.

The crocodile icefish takes being see-through to new heights because this fish not only has a transparent body, but even its blood is colorless. A lack of hemoglobin means that this fish’s blood carries less oxygen. To save oxygen, the crocodile icefish remains as still as possible until ambushing prey in the cold Antarctic waters.

Sea angel – Clione limacina

These see-through mollusks are as lethal as they are beautiful. Clione limacina shape-shifts into a more biblically accurate angel when it hunts, extending its razor-sharp tentacles to relieve prey of its protective shell and swallow it whole.

Sea angels are kinds of sea snails that have just as much variety as sea cucumbers. The see-through sea angels are called clione limacina. This particular sea angel’s meal of choice is another graceful mollusk, the sea butterfly. While this sea creature can be found all over the world in mid-zone waters as deep as 2000 feet, scientists are still mapping the range and depth of its habitat.

Barreleye fish – Macropinna microstoma

No list of see-through ocean creatures is complete without the iconic barreleye fish. This otherworldly fish has a see-through head and large eyes that help it scan for prey above. These large globe-like eyes, within a larger transparent domed head, rotate forward when the barreleye fish has made a catch. Scientists discovered about 15 years ago that barreleye fish can rotate their eyes.

The barreleye fish can reach up to six inches long and lives in the deep ocean. Although they have been documented for decades, the rarity of these alien-like fish maintains their celebrity. The barreleye fish has been spotted only about a dozen times over the last 30 years.

Our strange and wonderful ocean

Our ocean is truly a fascinating and wonderful place with creatures that are stranger than fiction. The marine life that keeps our ocean balanced and healthy relies on all of us as scientists, advocates and ocean lovers to speak up for them and keep their habitats clean.

That’s why Ocean Conservancy continues to fight for our ocean through comprehensive approaches that build international and domestic support for a clean, healthy ocean—and everything that lives within it.