Mollusks

While exploring the Tonga Trench in the Southwestern Pacific Ocean, researchers captured extremely rare footage of a Magnapinna squid with arms several times the length of its body.

The Pacific geoduck is a clam that lives along the shore from Alaska to Mexico, can reach 9 pounds in weight and can outlive humans.

Scientists discover what appears to be the second known living species of vampire squid swimming in deep water off Hainan island, China.

While navigating a remotely operated vehicle in the Gulf of California, scientists spotted a brooding squid cradling translucent eggs.

Watch rare footage of deep sea "octopus squid" reveal its bioluminescent photophores as it attacks an underwater camera.

Unusual octopus mating session captured in rare and comical footage filmed off the Indonesian island of Bunaken for new National Geographic show.

The blue dragon may be too weak to resist the ocean's current, but it can take on a Portuguese man o'war and even steal its venom.

The oldest-known sex chromosome emerged in octopus and squid between 455 million and 248 million years ago — 180 million years earlier than the previous record-holder, scientists have discovered.

Enigmatic octopuses that have been newly discovered in the waters off Costa Rica add to a growing registry of deep-sea dwellers.

Scientists have filmed one of the only squids known to brood their eggs — the black-eyed squid — swimming with thousands of unhatched offspring suspended from hooks on its arms.