By Stacey Venzel
Food is a motivating factor for any animal, not excluding turtles. From plant aficionados to meat eaters, turtles cover a wide range of dietary needs.
A mix of scavengers, foragers and hunters, a turtle’s diet can change depending on its age, habitat and opportunity. For the most part, species have food preferences based on their mouth structure which includes serrated, cusped, beaked, crushing and inhaling shapes.
Ridges resembling a butterknife assist grazing animals in sawing pieces of vegetation. Green sea turtles are especially noteworthy grazers as they feed mostly in sea grass beds, to the point that the algae has been nicknamed “turtle grass.”
Tortoises are predominantly herbivores with cusped mouths. They have their own set of pruning sheers to slice leaves, plants, fruits and vegetables. Even the giant Galapagos tortoise is a vegetarian! Aquatic turtles can have cusps, too, including the narrow-bridged mud turtle whose cusp aids in keeping hold of slippery frogs.
A sharp beak-like projection helps some turtles search for and tear their food. An alligator snapping turtles uses its sharp-edged mouth to spear a meal. Hawksbills need a beak to poke around coral reef holes in search of their main diet of sponges and then use the beak to tear the sponges apart.
The majority of aquatic turtles are carnivores. Powerful jaws on the wide, flat mouth and large head of the North American map turtle are beneficial in crushing mussels while the loggerhead sea turtle can snap its muscled mouth around crustaceans like lobsters and crabs.
A handful of species act like vacuum cleaners in the water. The matamata has a wide mouth ideal for sucking up fish. South American river turtles inhale small bits of floating food, shooting excess water out through their noses.
The diet of an individual or species can change based on age, habitat—a turtle on land cannot eat fish—and opportunity. A study on red-eared sliders is a shining example of these changes. In the same lake, juveniles were found to feed almost solely on other animals or insects whereas adults primarily ate vegetation. However, when these adults had access to the carnivorous diet, they took advantage of the added protein. Tortoises, too slow to hunt prey, are also opportunistic feeders, typically foraging but occasionally scavenging on dead animals.
Karen Eckert, David Gulko, Sea Turtles: An Ecological Guide (Honolulu, Mutual Publishing, 2004), 30, 32, 39.
Carl J Franklin, Turtles: An Extraordinary Natural History 245 Million Years in the Making (St. Paul, Voyageur Press, 2007), 28-29, 121.
Whit Gibbons, Judy Greene, Turtle: The Animal Answer Guide (Baltimore, The John Hopkins University Press, 2009), 76-77, 79.