Sea Turtles

Sea turtles (Chelonioidea) are a group of reptiles that inhabit salt and brackish waters. They have a hard shell covering their back and two front flippers resembling oars, which allow them to move swiftly through water. Unlike land turtles, sea turtles cannot fully retract their head and limbs inside their shell.

They breathe air through a blowhole, so they must surface regularly. They spend most of their lives in the ocean, but females lay their eggs on sandy beaches. They are migratory animals; some travel thousands of kilometers between feeding grounds and nesting beaches.

Appearance and structure

The shell consists of bone covered by a hard layer. Size varies by species: smaller species have shells under a meter long, while the largest—the leatherback—exceeds one meter. Sea turtles have no teeth; their beaks have a hard, claw-like structure suited to each species' diet.

Diet and daily life

Diet varies widely: some eat sea grass and algae, others eat jellyfish, crustaceans, small fish, and mollusks. Diet changes with age; juveniles of some species start as carnivores and later become herbivorous.

Reproduction

Females come ashore at night, dig a hole in the sand, lay many eggs, cover it, and return to sea. Sand temperature determines hatchling sex: warm sand typically produces females, cool sand males. Eggs hatch after about seven weeks, and hatchlings attempt to reach the ocean; many are preyed upon by birds and other predators.

Threats

Factors reducing populations include accidental capture in fishing nets, loss of nesting beaches due to development, artificial beach lighting that disorients hatchlings, plastic pollution ingested as food, and poaching of eggs and meat. Many countries and international agreements protect the species.