Sea turtles are ancient, globally distributed reptiles. Their long life history is punctuated by extreme vulnerability, as natural threats shift drastically from the moment an egg is laid to when the animal reaches adulthood. Only a small fraction of hatchlings survive the gauntlet of predators to reach maturity. The type of animal that preys upon a sea turtle depends entirely on the turtle’s size, location, and life stage.
Predation During the Nesting Phase
The nesting phase represents the first major hurdle, where buried eggs are defenseless against terrestrial predators. Mammalian species are effective at locating and destroying nests, often relying on smell to dig up the egg chamber. Common culprits across North American beaches include raccoons, foxes, feral dogs, and coyotes. Feral pigs and wild boars present threats in other global regions, often destroying an entire clutch of eggs in a single night.
Invertebrates and other small animals also contribute significantly to nest loss. Ghost crabs are abundant on many nesting beaches and tunnel into nests to consume eggs. Fire ants pose a threat by preying on unhatched eggs and newly pipped hatchlings. Their venomous stings can kill a vulnerable baby turtle before it leaves the nest.
Human coastal development can exacerbate this predation pressure. Residential areas and waste disposal sites often attract opportunistic mammalian predators, increasing their population density near nesting beaches. These animals learn to associate the smell of a freshly laid nest with an easily accessible food source, making the initial incubation period dangerous for developing embryos.
Threats to Hatchlings and Newly Hatched Turtles
Once hatchlings emerge from the nest, they face a harrowing crawl to the ocean, often called the “frenzy.” This short journey across the sand puts them directly in the path of numerous predators waiting on the beach surface. Ghost crabs, which also prey on eggs, are effective at ambushing hatchlings and dragging them into their burrows.
Avian predators exploit daylight hours, with gulls, frigate birds, and herons swooping down to snatch the small turtles. The simultaneous emergence of many hatchlings, known as predator swamping, is a survival strategy. This high mortality continues into the surf zone and nearshore waters, where threats shift rapidly from land-based animals to aquatic ones.
During the subsequent “lost years,” juvenile turtles drift in ocean currents and remain vulnerable to a wide array of marine life. Before their shells fully harden, young turtles are actively fed upon by:
- Small sharks
- Barracuda
- Snapper
- Grouper
The combined pressure from terrestrial, avian, and marine predators is so intense that estimates suggest fewer than one in a thousand hatchlings survive to reproductive maturity.
Predators of Mature Sea Turtles
As sea turtles grow, their armored shell and increased size deter most potential threats, leaving them with only a few specialized natural predators. The Tiger Shark is widely recognized as the most frequent and capable marine predator of large juvenile and adult sea turtles. Their broad heads and serrated teeth are adapted to cut through the thick carapace, allowing them to consume prey other sharks avoid.
Another apex predator of the open ocean is the Killer Whale, or Orca. Orcas have been documented preying on adult sea turtles, including the massive Leatherback Sea Turtle. They often hunt in coordinated groups and use powerful techniques to subdue their prey, overcoming the turtle’s physical defenses.
In specific coastal and estuarine environments, large reptiles pose a significant localized threat. Saltwater crocodiles in the Indo-Pacific and American crocodiles will prey on turtles in the water and occasionally ambush nesting females. Large land mammals, such as jaguars, have also been known to attack and consume female sea turtles as they nest on remote beaches.