Marine iguanas go out in the midday to forage on exposed algae at low tide. They scrape the algae from the rocks with their teeth. They then return to raise their body temperature by basking in the sun.
Larger iguanas actually dive underwater to forage. Their greater surface area-to-volume ratio allows them to lose body heat more slowly in the cold Galápagos waters.
Charles Darwin called them “disgusting, clumsy Lizards” and “imps of darkness,” but these reptiles are fascinating despite their rough appearance.