The hawksbill turtle lives on sponges and glows under the right light
Most reptiles would never touch a sea sponge, but for the hawksbill turtle sponges make up 70 to 95 percent of the menu. It is the only reptile that specialises in them. It was also the first reptile found to be biofluorescent, and its beautiful shell nearly drove it to extinction.
The hawksbill, Eretmochelys imbricata, is the only living member of its genus. Linnaeus described it in 1766 as Testudo imbricata; the Austrian zoologist Leopold Fitzinger moved it to Eretmochelys in 1843, a name built from Greek words for oar and turtle, after its paddle-like front flippers. The species name refers to the overlapping scutes on its back, which give the rear edge of the shell a jagged, saw-toothed outline. Its narrow head ends in a sharp, hooked beak that inspired the common name.
Adults usually grow to about a metre and weigh around 80 kilograms, though one captured specimen reached 127. The carapace has an amber base streaked with light and dark rays. Each front flipper bears two visible claws, and on a beach the turtle crawls with an alternating gait that leaves lopsided tracks. Molecular studies place it alongside the meat-eating loggerhead and ridley turtles rather than the plant-eating green turtle, suggesting its sponge habit evolved from carnivorous ancestors. Because it also eats venomous cnidarians, its flesh can be toxic.
Hawksbills are the sea turtles most tied to warm water, roaming tropical reefs in the Indian, Pacific and Atlantic Oceans, from the Gulf of Mexico to the Cape of Good Hope and from southern Japan down to northern New Zealand. By day they rest in reef caves and ledges, wedging their tough shells into tight gaps. In the eastern Pacific, where they were thought nearly wiped out as recently as 2007, surviving groups turned out to favour mangrove estuaries instead of reefs.
Their glow may come from diet, since they eat fluorescent corals, though nobody yet knows; males shine more intensely than females. The species is classified as critically endangered, largely because of fishing and because hawksbill shells were the main source of decorative tortoiseshell. International trade in the turtles and their products is regulated under the CITES convention.
Source: Hawksbill sea turtle
