These sea monsters grew upwards of 40 feet (12 meters) long. About half that length was neck, a feature that allowed Styxosaurus to sneak up on schools of fish as it slowly cruised the shallow ...

The ornately colored sea anemone (uh-NEM-uh-nee) is named after the equally flashy terrestrial anemone flower. A close relative of coral and jellyfish, anemones are stinging polyps that spend most ...

Sea dragons survive on tiny crustaceans such as mysids, or sea lice. It is not known if they are preyed upon by other animals. They are, however, frequently taken by divers seeking to keep them as ...

Smaller cephalopods and fish were likely dietary staples, though small marine reptiles that visited the ocean depths may have fallen prey as well. Tusoteuthis moved via jet propulsion—it ...

Females likely migrated hundreds of miles to lay eggs on sandy beaches, much like sea turtles do today. Movement onshore, however, was difficult. An adult female Protostega may have weighed a ton ...

Once prevalent in every ocean except the Arctic and Antarctic, the leatherback population is rapidly declining in many parts of the world. While all other sea turtles have hard, bony shells ...

(Learn about the peacock mantis shrimp with your kids ... while Red Sea mantis shrimp are beige with thin red stripes and a dark rear end. But all these animals are best known for their mighty ...

Xiphactinus was one of the largest bony fish of the Late Cretaceous and is considered one of the fiercest creatures in the sea. A powerful tail and winglike pectoral fins shot the 17-foot-long (5 ...

Read this story and more in the June 2018 issue of National ... Geographic magazine. On a boat off Costa Rica, a biologist uses pliers from a Swiss army knife to try to extract a plastic straw ...

The green turtle is a large, weighty sea turtle with a wide, smooth carapace, or shell. It inhabits tropical and subtropical coastal waters around the world and has been observed clambering onto ...

Mammals are among the most adaptable animals on the planet. They are found on every continent and in every ocean, and range in size from tiny bumblebee bats to enormous blue whales. One reason for ...