Turtles don’t share one diet. Over time, different species have become meat eaters, plant eaters, or a mix of both, so the useful question is which kind of turtle you’re looking at. What a turtle eats follows its lifestyle and habitat more than the simple fact of being a turtle. And a turtle’s menu isn’t always fixed for life, because some species change what they eat as they grow.1SeaWorld. Sea Turtles – Diet & Eating Habits
Which Turtles Eat Meat, Which Eat Plants, and Which Eat Both
Pond and river turtles are often omnivores, meaning they eat both plants and animals. The red-eared slider, the most common pet turtle, is an opportunistic omnivore that eats insects and other invertebrates, small vertebrates, and plants.2Asian Herpetological Research. Interspecific Differences in Diet between Introduced Red-eared Sliders and Native Turtles in China A slider in a weedy pond with few insects leans on plants, while one in a pond full of snails and tadpoles eats more animal food.3Asian Herpetological Research. Interspecific Differences in Diet between Introduced Red-eared Sliders and Native Turtles in China
The eastern box turtle is a generalist that eats plants, animals, and fungi such as mushrooms.4Herpetologica. Stable Isotopes Reveal Demographic Variation and Individual Repeatability in Diet of an Omnivorous Turtle A box turtle may eat worms, slugs, and insects on a damp morning and berries or mushrooms later in summer.
Land tortoises are mostly plant eaters; most, such as the Greek tortoise, are built for a plant diet.5PubMed. Macroscopic, microscopic, and immunofluorescent characterization of the Greek tortoise (Testudo graeca graeca) oropharyngeal floor with concern to its feed adaptation as a herbivorous land reptile Many tortoises and turtles also eat fruit, with at least 71 species known to include fruits or seeds in their diet.6PubMed. Frugivory and seed dispersal by chelonians: a review and synthesis A few African tortoises are omnivores rather than strict herbivores.7Canadian Journal of Zoology. Digestive efficiency and gut morphology of omnivorous and herbivorous African tortoises
Tortoise usually means a land-dwelling turtle, and life on land goes with tougher, plant-based foods. Calling every shelled reptile a turtle hides big diet differences, so the first step for any owner is to check the exact species.
Sea turtles split by species. In the Mediterranean, adult green sea turtles ate mostly seagrasses and algae, about 89% of their diet.8Marine Biology. Dietary analysis of two sympatric marine turtle species in the eastern Mediterranean Loggerheads living in the same waters were mainly meat eaters, with about 72% of their diet coming from animals like crabs, shellfish, and fish.9Marine Biology. Dietary analysis of two sympatric marine turtle species in the eastern Mediterranean Leatherbacks feed largely on jellyfish,10PubMed Central. Jellyfish Support High Energy Intake of Leatherback Sea Turtles (Dermochelys coriacea): Video Evidence from Animal-Borne Cameras and hawksbills feed largely on sponges on coral reefs.11PubMed. Spongivory in hawksbill turtles: a diet of glass
Many Turtles Change Their Diet as They Grow
Green sea turtles are mainly carnivorous from hatching until juvenile size, then gradually shift to a plant diet.12SeaWorld. Sea Turtles – Diet & Eating Habits The smallest green turtles get most of their food from animal prey, while those over about 40 cm (16 in) shell length eat mostly seagrass.13Marine Biology. Ontogenetic diet shifts of green sea turtles (Chelonia mydas) in a mid-ocean developmental habitat The shift is slow, though, and green turtles of all sizes still eat some animal food.14Marine Biology. Dietary analysis of two sympatric marine turtle species in the eastern Mediterranean
Loggerheads change in a different way. Young ones eat soft prey in the open ocean, then move to coastal waters and hard-shelled bottom prey.15PubMed Central. The ontogenetic scaling of bite force and head size in loggerhead sea turtles (Caretta caretta): implications for durophagy in neritic, benthic habitats By the time they make that move, their bite is strong enough to crush small hard-shelled animals.16PubMed Central. The ontogenetic scaling of bite force and head size in loggerhead sea turtles (Caretta caretta): implications for durophagy in neritic, benthic habitats
Young turtles lean toward animal food because a baby turtle is growing very fast, and growth takes a lot of protein. Animal prey packs more protein per bite and is easier to digest than tough plant material, and a hatchling’s gut bacteria have to build up over time.
A juvenile slider’s needs differ from an adult’s, so the adult diet shouldn’t be assumed to suit a hatchling. A reptile vet can say how the mix should change with age.
How Meat-Eating Turtles Catch Their Food
Snapping turtles rely on power and trickery. The alligator snapping turtle has a pink appendage on its tongue that it wiggles like a worm to lure fish.17PubMed. Functional mechanisms and histologic composition of the lingual appendage in the alligator snapping turtle, Macroclemys temmincki (Troost) (Testudines: Chelydridae) It rests on the bottom with its mouth open, looking like part of the mud and debris, and a fish that comes to investigate ends up within reach.
Alligator snapping turtles also bite harder than common snapping turtles at every size.18Southeastern Naturalist. Bite-Force Scaling across Size Classes in the Alligator Snapping Turtle (Macrochelys temminckii) and the Common Snapping Turtle (Chelydra serpentina) Bite force rises as a turtle grows, and alligator snappers grow much larger.19Southeastern Naturalist. Bite-Force Scaling across Size Classes in the Alligator Snapping Turtle (Macrochelys temminckii) and the Common Snapping Turtle (Chelydra serpentina)
Leatherbacks have a throat built for jellyfish. Spines line the throat and point toward the stomach, helping hold slippery prey.20PubMed Central. Jellyfish Support High Energy Intake of Leatherback Sea Turtles (Dermochelys coriacea): Video Evidence from Animal-Borne Cameras Very large jellyfish with long tentacles are still hard to handle and can limit how much a leatherback eats.21PubMed Central. Jellyfish Support High Energy Intake of Leatherback Sea Turtles (Dermochelys coriacea): Video Evidence from Animal-Borne Cameras
Some predators even shape reefs. By eating sponges that compete with coral for space, hawksbills may help corals indirectly.22Marine Ecology Progress Series. Selective feeding in the hawksbill turtle, an important predator in coral reef ecosystems
How Turtles Eat Without Teeth
Turtles have no teeth. Their jaws are covered in a beak, a hard edge made of the same material as fingernails. Plant-eating turtles tend to have more complex, ridged beak surfaces than meat eaters, much as plant-eating mammals have more complex teeth.23PubMed. The topography of diet: Orientation patch count predicts diet in turtles The Greek tortoise has a V-shaped lower beak with a serrated edge that saws through plants,24PubMed. Macroscopic, microscopic, and immunofluorescent characterization of the Greek tortoise (Testudo graeca graeca) oropharyngeal floor with concern to its feed adaptation as a herbivorous land reptile and its upper jaw has interlocking hard plates that take the place of teeth.25PubMed Central. Macro- and micro-anatomical investigation of the oropharyngeal roof of landform greek tortoise (Testudo graeca graeca) and semi-aquatic red-eared slider turtle (Trachemys scripta elegans)
A sharp, hooked beak fits a predator that needs to grip and tear prey, while serrated or ridged edges fit plant eaters. It’s a clue to lifestyle and not a perfect test, since many turtles eat a mix of foods.
Without teeth to chew, turtles tear food into chunks and swallow them. Many water turtles need to be in water to swallow, so pet pond turtles should be fed in water. Land tortoises eat on land.
How Plant-Eating Turtles Digest Tough Greens
Plant-eating turtles depend on gut bacteria to break down the tough fiber in plants.26PubMed. Kinship, inbreeding and fine-scale spatial structure influence gut microbiota in a hindgut-fermenting tortoise Bacteria ferment it, turning plant matter into nutrients the turtle can absorb.
Pet tortoises of several species share a core set of gut bacteria that break down fiber.27PubMed Central. Gut microbiota variation in captive tortoises is associated with host species, trophic category, and growth rate Diet shapes the rest. Plant-eating green sea turtles have a more varied gut bacteria community than sponge-eating hawksbills,28PubMed. Metagenomic comparison of gut communities between hawksbills (Eretmochelys imbricata) and green sea turtles (Chelonia mydas) and tortoises fed branches and leaves carry more of the bacteria that digest woody material.29PubMed Central. Disentangling the gut microbiota of Aldabra giant tortoises of different ages and environments
Because those bacteria are tuned to the usual foods, a sudden switch can cause digestive upset. Changing foods gradually over weeks is gentler, and fibrous greens and weeds suit most grazing tortoises.
Gut length matters too. The leopard tortoise, a grazer, has a large intestine about three times longer relative to its shell than the omnivorous hinge-back tortoise.30Canadian Journal of Zoology. Digestive efficiency and gut morphology of omnivorous and herbivorous African tortoises Food takes longer to first pass through the leopard tortoise, about 3.8 days versus 2.2.31Canadian Journal of Zoology. Digestive efficiency and gut morphology of omnivorous and herbivorous African tortoises
Turtles as Seed Planters
Turtles and tortoises eat or spread the fruits of at least 588 plant species.32PubMed. Frugivory and seed dispersal by chelonians: a review and synthesis Because turtles move on after eating, seeds are often dropped away from the parent plant, in droppings that act as a bit of fertilizer.
Passing through a gut can help some seeds. Seeds of fleshy fruits that pass through a gopher tortoise sprout more often and faster.33The American Midland Naturalist. Gopher Tortoise (Gopherus polyphemus) Gut Passage Can Alter Seed Germinability But seeds of dry fruits are unaffected or even sprout worse after passing through.34The American Midland Naturalist. Gopher Tortoise (Gopherus polyphemus) Gut Passage Can Alter Seed Germinability
Feeding a Pet Turtle or Tortoise the Right Way
Captive tortoises fed an improper high-energy diet developed soft shell and gout.35Applied Herpetology. Growth and body composition in captive Testudo graeca terrestris fed with a high-energy diet Young sliders fed extra calcium grew about half as much as those on a standard diet.36Zoo Biology. Calcium and phosphorus supplementation decreases growth, but does not induce pyramiding, in young red-eared sliders, Trachemys scripta elegans Extra calcium or phosphorus did not cause pyramiding, the lumpy raised shell.37Zoo Biology. Calcium and phosphorus supplementation decreases growth, but does not induce pyramiding, in young red-eared sliders, Trachemys scripta elegans
Matching food to species is the main safeguard. A tortoise should be fed mostly greens and weeds, not meat. Sliders do better on a mix of animal and plant foods. Commercial pellets can be part of a diet but shouldn’t be all of it, and a reptile vet should be asked before supplements are added.
Some signs suggest a diet may be off: a shell that feels soft or flexes, slow growth or poor appetite, and lumpy or deformed scutes. Any of these is worth a vet check.
Why Sea Turtles Mistake Plastic for Food
Plastic that floats and moves like prey is easy for sea animals to mistake for food.38Frontiers in Marine Science. Plastic Ingestion in Post-hatchling Sea Turtles: Assessing a Major Threat in Florida Near Shore Waters Sea turtles pick objects whose color resembles their usual food, and soft textures are more often swallowed whole.39PubMed. Experimental study on color and texture as cues for plastic debris ingestion by captive sea turtles In one study, 75% of green turtles and 57% of loggerheads had eaten debris.40PubMed. Junk food: Interspecific and intraspecific distinctions in marine debris ingestion by marine turtles Green turtles tended to swallow soft items like threads and sheets, while loggerheads swallowed hard pieces.41PubMed. Junk food: Interspecific and intraspecific distinctions in marine debris ingestion by marine turtles
A jellyfish eater is at special risk. Floating plastic bags can look like jellyfish in the water, and leatherbacks feed almost only on jellyfish, so they are primed to go after such shapes. Their backward-pointing throat spines make spitting out a swallowed item difficult.