Hawksbill sea turtles

The hawksbill sea turtle (Eretmochelys imbricata) is the only living species in the genus Eretmochelys.
The hawksbill's appearance is similar to that of other marine turtles. In general, it has a flattened body shape, a protective carapace, and flipper-like limbs adapted for swimming in the open ocean. E. imbricata is easily distinguished from other sea turtles by its sharp, curving beak, and the saw-like appearance of its shell margins. Hawksbill shells slightly change colours, depending on water temperature. While this turtle lives part of its life in the open ocean, it spends more time in shallow lagoons and coral reefs.
Due to its consumption of venomous cnidarians, hawksbill sea turtle flesh can become toxic.
The hawksbill is biofluorescent and is the first reptile recorded with this characteristic. It is unknown whether the effect is due to the turtle's diet, which includes biofluorescent organisms like the hard coral Physogyra (bubble coral). While they are omnivorous, sea sponges seem to be their principal food (70–95% of the turtle's diet). However, like many spongivorous, they feed only on selected species, ignoring many others. Aside from sponges, hawksbills feed also on algae, marine plants, cnidarians, comb jellies and other jellyfish, sea anemones, mollusks, fish and crustaceans. They also feed on the dangerous jellyfish-like hydrozoan, the Portuguese man o' war (Physalia physalis). Hawksbills close their unprotected eyes when they feed on these cnidarians.