Nekton are aquatic animals that swim or move freely in the water. Their movement is generally not controlled by waves and currents. Nekton include fish, squid, marine mammals, and marine reptiles. They live in the sea, lakes, rivers, ponds, and other bodies of water.

Fish are a major segment of the nektonic animals, with approximately 14,500 kinds of fish living in the ocean. Many nekton live near the ocean surface because food is abundant there. Other nekton live in the deep ocean.

Most nekton are chordates, animals with bones or cartilage. This category of nekton includes whales, sharks, bony fish, turtles, snakes, eels, dolphins, porpoises, and seals.

Molluscan nekton like squid and octopus are invertebrates, animals with no bones. Squid, octopus, clams, and oysters are mollusks. However, molluscan nekton have no outer shells.

Molluscan nekton like squid and octopus are invertebrates, animals with no bones. Squid, octopus, clams, and oysters are mollusks. However, molluscan nekton have no outer shells.

Arthopod nekton are invertebrates like shrimp. Many arthropod live on the ocean floor.

Most nektonic mammals live only in water. However, walruses, seals, and sea otters can exist on land for a time. Other nekton mammals include manatees and dugongs, whale-like animals that live in the Indian Ocean.