Invertebrates

Animals without backbones make up a huge percentage of the ocean’s biodiversity. They aren’t just small (like pteropods) or squishy (like jellyfish); the giant squid and corals that build huge reefs are also invertebrates.

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A reddish-orange nudibranch.

DIVE DEEPER

A Collage of Nudibranch Colors

Nudibranchs are a kind of sea slug, and their 3000 species are found from the poles to the tropics in both shallow and deep...

Searching for Crustaceans in the Deep Sea

In this video Smithsonian research zoologist Dr. Martha Nizinski takes viewers with her as she searches for crustaceans in the deep sea . She's particularly interested in finding squat lobsters , which despite their...

Video of Cirrate Octopod aka Dumbo Octopus

This octopod is sometimes called a “Dumbo” octopod because its fins resemble the ears of Disney’s Dumbo the elephant. The video was recorded in 2003 on the Mid-Atlantic Ridge by the Russian manned submersible...
A bloom of moon jellies.

A Bloom of Moon Jellies

In recent years, blooms of jellyfish, such as these moon jellies ( Aurita aurita ) in the Chesapeake Bay, have become more common around the world for a number of different reasons . One...

The Amazing Horseshoe Crab

There’s a lot more to a horseshoe crab than meets the eye. They are not even crabs and are actually more closely related to spiders and scorpions. They don’t have teeth or jaws, and...
Sea otters floating on the surface of the ocean.

Not Just Another Fuzzy Face

A raft of sea otters grooming and resting after foraging. Credit: © Elise Newman Montanino Who hasn’t grinned at the sight of a sea otter floating on its back while grooming itself? No doubt...

Anemone Feeding Time

Anemones are known for serving as homes for Nemo and countless other small fish and invertebrates. But these Cnidarians (in the same phylum as jellyfish and same class as corals ) have a long...
Two nautiluses in the open ocean off the coast of Palau.

A Couple of Nautiluses

These two nautiluses ( Nautilus belauensis ) are pictured off the coast of Palau in the Pacific Ocean. There are six living species of nautilus who live in chambered shells. As they get bigger,...
A variety of jellyfish

It’s All in the (Jellyfish) Family

They may not all look the same, but cnidarians all have cells that are specially designed for stinging. Credit: Allen Collins, Smithsonian By Kalila Morsink With their huge number of venomous stinging cells, jellyfish...

Jellyfish predate dinosaurs. How have they survived so long?

Gelatinous drifters that move in a mesmerizing way, jellyfish are beautiful creatures. But take a closer look and you'll see there's more to these creatures than a pretty picture. Some shoot a deadly venom,...

Farming Oysters Despite Acidic Seas

Bill Taylor, Paul Taylor, Diani Taylor and Brittany Taylor have more in common than just a last name; they also share a business. The Taylors have been in the family oyster-farming business in Washington...

Oil’s Impact on Marine Invertebrates

In the aftermath of the Gulf oil spill, what is the effect of oil on invertebrates like jellyfish, clams, crabs, sea stars, and plankton? The scope of the damage is more easily observed among...

Deep-sea octocorals: An ecosystem of their own

Octocorals dominated the seafloor on Chris Mah's Okeanos mission to Johnston Atoll in the remote Pacific Ocean. Credit: NOAA Office of Ocean Exploration and Research, 2017 Laulima O Ka Moana The deep-sea is a...

Jellies Prey on Octocoral

Tiny jellyfish ( Aegina citrea ) settle on the feeding polyps present on the branch tips of some octocorals, where they devour the tissue.

Sea Stars Feed on Octocorals

Spiny goniasterid sea stars methodically feed on the soft tissues of octocorals as they slowly climb up the body. Many of these predatory sea stars are known to remain on the corals for a...

A Battle With Octocoral for Food

Although not strictly speaking a predator, a sea-anemone-like animal called a zoanthid overtakes the surface of some Paragorgia octocoral colonies, crowding over the original coral animal and competing with the coral’s polyps for food.

Glowing Dinoflagellate Meal

Watch as barnacles feed on bioluminescent dinoflagellates. Barnacles are crustaceans (like crabs, shrimps and lobsters) that secrete their shells for protection while living attached to things like rocks, harbors or boat hulls. They feed...

Why the Octopus Brain is so Extraordinary

An octopus is a lot brainier than you might imagine considering one of its closest living relatives is a sea slug. In fact, some scientists argue it could be the first intelligent being on...

Red Paper Lantern Jellyfish: One Species at a Time

The Encyclopedia of Life brings us a new installment of the podcast, One Species at a Time . Vacuumed up from its habitat a mile down in the ocean, the red paper lantern jelly...

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