What Do Sea Turtles Eat?

What do sea turtles eat
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What Do Sea Turtles Eat?

Turtles can be divided into three subgroups, namely freshwater turtles (commonly referred to as turtles), land tortoises (commonly referred to as tortoises), and sea turtles. As evident by their name, sea turtles can be found in the sea.

These chelonians spend most of their lives in water, and usually only venture out to lay eggs. So what do sea turtles eat? Well, this will depend on the species as well as the habitat of the species.

Of course, sea turtles housed in artificial enclosures have to be fed by humans and as such, their diets are usually different from that of wild sea turtles. Since sea turtles are not kept as pets, this article tackles their dietary needs in the wild.

Most sea turtle species are generally omnivores feeding on both vegetation and animal matter. Others such as the leatherback turtles and hawksbill turtles have diets consisting mainly of just one food type.

For example, leatherback sea turtles feed primarily on soft-bodied invertebrates such as jellyfish. Hawksbill turtles, on the other hand, feed primarily on sponges which are found on coral reefs.

Do sea turtles eat jellyfish?

All species of sea turtles feed on jellyfish. However, leatherback turtles are the only sea turtles that feed primarily on jellyfish.

Feeding Habits of the Green Sea Turtle (Chelonia mydas)

green sea turtle
Green Sea Turtle

The dietary needs of the green sea turtles (Chelonia mydas) change with age. While hatchlings and juveniles are more carnivorous, adults are primarily herbivorous. Growing green sea turtles need more protein more than adults do. So what do green sea turtles eat?

Preys eaten by young green sea turtles include crustaceans, sponges, worms, small marine invertebrates, mollusks, neustonic organisms like sea serpents (Hydrozoa), jellyfish, sea insects, moss animals (Bryozoa), and fish eggs (such as sea hare eggs (Aplysia)). Juveniles also eat the plant matter just like the adults eat.

 Adults, on the other hand, do not eat animal foods. Some plants that green sea turtle consume include a wide variety of red and green algae, salt-water cordgrass (Spartina alterniflora) found in salt marshes, and api-api (Avicennia schaueriana), crinkle grass (Rhizoclonium), green seaweed (Gayralia), sea lettuce (Ulva lactuca), and lobster horns (Polysiphonia).

The algae the turtle eats include freshwater red algae (Compsopogon), red moss (Caloglossa), and filamentous red algae (Bostrychia).

As opportunistic feeders, these turtles eat what is available. There is a correlation between the dietary shift and the turtle’s physiological changes. As the turtle grows, the morphology of the skull changes. The serrated jaw of adults helps them effectively consume vegetation.

Feeding Habits of the Loggerhead Sea Turtle (Caretta caretta)

loggerhead sea turtle swimming
Loggerhead Sea Turtle

Loggerhead sea turtles, commonly known simply as loggerheads are omnivorous. Their diet consists mostly of bottom-dwelling invertebrates such as shrimps, decapods, bivalves, and gastropods. While these foods are the species’ primary food source, the loggerhead has the largest prey list of any oceanic turtle.

Other preys that the loggerhead commonly eats include sea cucumber, aquatic insects, fish (including hatchlings, adults and eggs), starfish, sand dollars, sea urchins, bryozoans, Portuguese man o’ war (Physalia physalis), isopods, brachiopods, barnacles, cephalopods, sea anemones, bristle worms, and sea pens.

During migration, these interesting species feed on flying fish, squid, floating egg clusters, floating mollusks, and jellyfish. They also feed on juvenile turtles including juvenile loggerheads.

Plants that the loggerhead feed on include vascular plants also known as tracheophytes, algae,  seaweeds, and corals.

The loggerhead sea turtles as large and powerful jaws which they use to crush their food before swallowing.

Feeding Habits of the Kemp’s Ridley Sea Turtle

kemp's ridley sea turtle (lepidochelys-kempii)
Kemp’s Ridley Sea Turtle

The Kemp’s ridley sea turtle is the rarest sea turtle in the world. This rare species is unsurprisingly critically endangered. This turtle species is also the smallest of the sea turtles.

The Lepidochelys kempii is omnivorous but feeds primarily on floating crabs. Other preys of this sea turtle include jellyfish, shrimps, mollusks, fish, crustaceans, and sea urchins. Plant matter the Kemp’s ridley sea turtle eats include algae, seaweeds, and vegetation.

Feeding Habits of the Leatherback Sea Turtle (Dermochelys coriacea)

Leatherback Sea turtle
Leatherback Sea Turtle

The Leatherback sea turtle is the heaviest turtle species and the fourth largest modern reptile. The leatherback is called as such because of the lack of a bony shell. Instead, skin and oily flesh cover their carapace. So what do leatherback turtles eat?

The leatherback sea turtle feeds primarily on jellyfish. Occasionally, leatherback turtles eat other soft-bodied invertebrates such as cephalopods and tunicates.

Because the D. coriacea feeds primarily on jellyfish, they help control the worldwide jellyfish populations. The jellyfish population boom has several harmful ecological effects.

The leatherback sea turtle is endangered mainly due to ocean plastic pollution. The D. coriacea confuses floating plastic materials for jellyfish. Ingestion of plastic can lead to serious health complications as they cannot digest plastic.

Pacific leatherbacks are particularly affected by plastic pollution as they migrate from Indonesia to California. Californians use over 19 billion plastic bags annually with a large percentage of these plastic ending up in the ocean.

Ingesting even the smallest of plastic marine debris can obstruct the digestive tract and cause impaction. This leads to a lack of appetite, constipation and the inability to eat.

Even when plastic doesn’t cause impaction, it caused nutrient dilution whereby the turtle is unable to absorb the required amount of nutrients needs to mature. Slow maturation means the turtle is slow to reach sexual maturity. This impacts reproduction rates. 

Feeding Habits of the Olive Ridley Sea Turtle

young olive ridley (lepidochelys-olivacea)
Baby Olive Ridley Sea Turtle

The olive ridley sea turtle is primarily a carnivorous turtle that feeds on invertebrates such as crabs,  tunicates, shrimp, sea urchins, snails, bryozoans, bivalves, lobsters, worms, and jellyfish. They feed in shallow marine waters and estuarine habitats. They mostly feed in shallow soft bottomed waters.

Devoid of all other food sources, the olive ridley will feed on filamentous algae such as the filamentous red algae (Bostrychia).

In captivity, the species have been observed to be cannibalistic. However, this has been observed to happen only in captivity.

Plastic pollution also harms this species as they usually attempt to eat plastic bags and Styrofoam. This causes a blockage of the digestive tract as well as nutrient dilution.

Feeding Habits of the Hawksbill Sea Turtle (Eretmochelys imbricata)

hawksbill sea turtle
Hawksbill Sea Turtle

The critically endangered hawksbill sea turtle is an omnivorous species that feeds primarily on animals with their main food source being sea sponges, which can make up to 95 percent of their diets. Due to their dietary needs, the hawksbill sea turtle is referred to as spongivorous species.

Although E. imbricata is a spongivore, it only eats specific sponge species. Hawksbill turtles found in the Caribbean primarily feed on sponges form the class Demospongiae, and the orders Hadromerida, Spirophorida, Astrophorida.

One highly toxic jellyfish species the hawksbills feed on include the hydrozoan, Portuguese man o’ war (Physalia physalis). They close their eyes when they feed on the dangerous man o’ war so as not to get stung in the eyes (the only vulnerable part of their face). The rest of their head is heavily armored and adequately protected.

They also feed on highly toxic sponges such as the Suberites domuncula, Spheciospongia vesparium, Tethya actinia, Chondrilla nucula, and Aaptos aaptos. Hawksbills are resistant to the toxicity of these sponges. 

Other food sources include sea anemones, jellyfish, comb jellies, cnidarians, and algae.

Feeding Habits of the Australian Flatback Sea Turtle (Natator depressus)

Flatback-Sea-Turtle
Flatback Sea Turtle

The Natator depressus which is native to Australia is the only sea turtle that is mostly confined to a single geographic range which is the northern waters of Australia. All the seven sea turtle species, the flatback turtle has the smallest geographical range.

The flatback sea turtle is carnivorous and hardly ever feed on vegetation. Food items that make up their diet include soft corals, bryozoans, shrimps, prawns, jellyfish, mollusks, sea cucumber and other sea invertebrates that live in shallow waters.

Conclusion

Sea turtles are interesting creatures although many of them are endangered. Generally, they tend to eat small marine animals such as crustaceans, sea sponges, squids, shrimps, jellyfish, and sea anemones.

Apart from the adult green sea turtle, which is mostly herbivorous, most sea turtles are generally omnivores. What sea turtles eat can sometimes be determined by the physiology of the mouth and jaws. Different mouth and jaw shapes help the turtle efficiently consume different food types.

Leatherback turtles have sharp pointed cusps on their jaws which is particularly helpful when they have to catch and hold onto jellyfish and other soft-bodied invertebrates. Also, with the help of the papillae ( a series of sharp downward curving spines found in the mouth and throats of leatherbacks), leatherbacks can easily swallow their prey.

Loggerhead sea turtles have massive and powerful jaws which they use to crush shelled animals such as sea snails and conchs. The serrated saw-like beak of the green sea turtle helps it to efficiently tear seagrass and scrape algae off surfaces. 

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