This iguana feeds almost exclusively on algae, and large males dive to find this food source, while females and smaller males feed during low tide in the intertidal zone. They mainly live in colonies on rocky shores where they warm after visiting the relatively cold water or intertidal zone, but can also be seen in marshes, mangrove and beaches.
Large males defend territories for a short period, but smaller males have other breeding strategies. After mating, the female digs a nest hole in the soil where she lays her eggs, leaving them to hatch on their own a few months later.
Marine iguanas vary in appearance between the different islands and several subspecies are recognized. Although relatively large numbers remain and it is locally abundant, this protected species is considered threatened, primarily from El Niños, introduced predators and chance events like oil spills.
