A Santiago marine iguana (Amblyrhynchus cristatus mertensi) ascends to the surface after grazing on algae off the rocks below. Marine iguanas only eat a few species of algae which are reliant on the cold ocean currents to grow. In El Nino events, when the waters around the Galapagos warm, the iguana’s food source stops growing causing them to starve. Sadly, in severe El Nino events, large scale iguana mortalities are common.