Corals and Other Invertebrates Archives - Oceana

Pacific Purple Sea Urchin

Urchins on the Pacific seafloor, including purple sea urchins, are important prey for sea otters and sea stars. Pacific purple sea urchins are also eaten by humans. The meat inside, known as “uni” in Japanese,2 is considered a sushi delicacy, and the demand for this delicacy has been growing in recent years. Pacific purple sea urchins … Read more

Christmas Tree Worm

Christmas Tree Worms are ciliary feeders, which means they use cilia, tiny-hair-like bristles on their appendages, to catch food as it passes by. The food then passes down a groove pushed by their ciliary tracts, which are lines of tiny hair-like extensions on the sources of cells that create water currents to direct digestion. Through … Read more

Fried Egg Jellyfish

This jellyfish spends a lot of time motionless, slowly pulsing its bell while drifting. The numerous short, club-like appendages extending from it contain mouth-arm openings through which the jellyfish traps prey and feeds.1 The primary prey of the Fried Egg Jellyfish is zooplankton and other jellyfish. These appendages are usually colored a deep purple and while … Read more


The bluebottle is comprised of four different colonies of polyps that depend on each other to survive. The species is named after one of its polyps, the gas-filled sac, often referred to as “the float,” which resembles a blue bottle floating in the ocean. The float moves depending on the wind and supports the other … Read more

Blue Glaucus

Despite its impressive arsenal of defense tactics, the blue glaucus rarely reaches more than 3 centimeters long. And, unlike most benthic nudibranchs, this species lives throughout the entire water column. An air bubble stored in its stomach keeps the nudibranch afloat. The creature often floats on its backside, showing its brightly colored underbelly to airborne … Read more

Lion’s Mane Jellyfish

The lion’s mane jellyfish cannot be missed in the open ocean where it prefers to float about. With tentacles up to 120 feet long, some individuals even rival in size the blue whale, the largest animal in the world. Most lion’s mane jellyfish live in the Arctic and North Pacific Ocean from Alaska to Washington … Read more

Felimare Cantabrica

Felimare cantabrica, like all nudibranchs, is simultaneously hermaphroditic – each individual produces both eggs and sperm. An individual cannot fertilize its own eggs, however, and pairs still must mate. They reproduce via internal fertilization and lay eggs, which they stick to the reef surface or other hard substrates. The long strings of eggs are often spiral shaped. Neither parent … Read more

Chilean Basket Star

Chilean basket stars are filter feeders. They cannot swim, but are highly mobile and crawl to the top of sponges or other structures in order to extend their branched arms into the water column. Using the hooks and spines that cover their arms, individuals capture pelagic invertebrates (e.g., antarctic krill) that venture too close. After prey is ensnared, … Read more

Portuguese Man o’ War

The Portuguese man o’ war is a predatory species. It uses its feeding tentacles to sting and paralyze small fishes, pelagic crustaceans, and other invertebrates. The feeding tentacles may be up to 160 feet (50 m) long in some individuals! These tentacles deliver a powerful sting and are also used for defense against predation. Few species eat the Portuguese … Read more


The bright orange, white-tipped structures along the flameback’s dorsal surface are called cerata and increase the surface area of the skin. This nudibranch absorbs oxygen through its skin, so increased surface area aids in respiration. The cerata also increase the number of defense cells that the flameback can store from its prey. The flameback, like all nudibranchs, is … Read more