Green sea turtles, manatees, dugongs and marine iguanas are some examples of herbivorous marine animals. They have adapted to feeding exclusively on algae and other plant matter.
The endangered green sea turtle is a marine reptile that thrives exclusively on algae and sea grasses. Although it is carnivorous from hatching to the early stages of its life, once a turtle has passed the juvenile age and reached an average length of 10 inches, it begins to alter its diet from meat to plants. Adult green sea turtles are the only herbivorous sea turtle.
Manatees and dugongs are voracious herbivores that feed on weeds, water grasses and algae. In order to survive, they are required to eat up to one-tenth of their body weights daily. Manatees and dugongs migrate to more temperate or tropical coastal waters during winter to feed on a wide variety of floating and emergent shoreline vegetation.
Despite a fierce look and razor-sharp teeth, marine iguanas are actually gentle marine herbivores that exclusively feed on algae and seaweed. The only known marine lizards, marine iguanas inhabit the Galapagos Islands. Their coppery red and green scales are believed to be a result of feeding on a specific type of seaweed that blooms around the islands in the summer months.