Which lizard is the only one that forages in the ocean?

The marine iguana is the only living lizard known to forage in the ocean. It grazes mainly on red and green algae in the intertidal and subtidal zones around the Galápagos Islands.

Large males commonly dive for algae, while females and smaller males usually feed from exposed rocks during low tide. A flattened tail helps propel the animal, and dense limb bones provide ballast. After feeding in cold water, the iguana must bask in the sun to restore its body temperature.

This is not a lizard that merely lives near the sea: it regularly enters marine water to obtain food. Salt glands near the nostrils remove excess salt, and algae digestion depends partly on gut microorganisms. Marine iguanas are endemic to the Galápagos and are vulnerable to El Niño events, which can sharply reduce their algal food supply.