Green Sea Turtle

The Galapagos Green Turtle (Chelonia mydas agassizii) is the only sea turtle to nest in the Galapagos Islands and one of the most frequently sighted marine animals in the archipelago. Often seen gliding through shallow lagoons and bays, these graceful herbivores feed primarily on algae and seagrass, playing a vital role in the marine ecosystem. Two types — the dark “black” and the golden “yellow” — can be seen in the Galapagos Marine Reserve, where they live up to 80 years and grow over a metre long. Between December and March, females come ashore at night to lay their eggs, continuing a cycle that has endured for millions of years.

Discover where and when to see Galápagos Green Turtles on Safari, their conservation status, and how initiatives led by the Galápagos National Park are protecting these ancient ocean voyagers for future generations.

Only turtle to breed in the Galapagos

The Galapagos Green Turtle is one of the archipelago’s most emblematic marine species, and the only sea turtle to breed in the islands. This subspecies of the Pacific Green or Black Turtle is also among the most abundant, easily spotted in lagoons, coves, and shallow coastal waters surrounding the islands.

With life spans reaching 80 years and adults weighing up to 136 kilograms, these gentle reptiles have roamed the world’s oceans for more than 100 million years, long before the first humans appeared on Earth.

Appearance

Two distinct colour forms of Green Turtle can be seen in the Galápagos:

The black morph, with a slightly flattened, triangular carapace varying from dark green to near-black tones, is the one that nests in the islands.

The rarer yellow morph has an oval shell patterned with radiating orange and gold markings. These turtles feed in Galapagos waters but migrate to the Indo-Pacific to nest.

The carapace of both forms can exceed 1.3 metres in length, giving them a commanding presence beneath the surface. Their serrated lower jaw, which distinguishes them from other marine turtle species, is an adaptation for grazing on seagrasses and algae.

Feeding and behaviour

Adult green turtles are largely herbivorous, spending much of their lives grazing on marine algae in the shallow bays and lagoons around the islands. Juveniles, however, are opportunistic feeders and may consume small invertebrates until they mature and settle into a plant-based diet.

Despite their size, they are agile swimmers, capable of reaching speeds up to 35 mph (56 km/h) when threatened or migrating between islands. They can rest submerged for several hours, surfacing periodically to breathe, although stress, such as entanglement in fishing gear, can drastically reduce that time.

An extraordinary physiological feature allows them to excrete excess salt through glands near their eyes, producing what appear to be “tears”. A clever adaptation for life at sea.

Mating and Nesting

Mating occurs during the warm season (December to March), when pairs can be seen floating near the surface offshore. The smaller male clings to the female’s shell, often accompanied by rivals awaiting their turn.

At night, females haul themselves up sandy beaches above the high-tide line to dig their nests. Using their rear flippers, they carve a deep chamber and lay between 50 and 200 eggs at a time, covering the nest before returning to the ocean before dawn. Each female may nest several times in a season.

The temperature of the nest determines the sex of the hatchlings. Warmer sand produces more females, cooler sand more males, making them highly sensitive to climate change.

After 45–60 days, the hatchlings emerge in unison, instinctively racing toward the sea. Yet their survival odds are slim: frigatebirds, crabs, hawks, and fish take most before they reach open water. Of the hundreds of eggs laid, perhaps one in a thousand will reach adulthood.

Threats and conservation

Like all sea turtles, the Galapagos Green Turtle faces a complex web of threats, from climate change and light pollution to marine plastics and fishing bycatch.

Predation: Rats, cats, and feral pigs dig up nests or feed on hatchlings, while Trox suberosus beetles can destroy entire clutches of eggs.

Pollution: Many turtles are found entangled in discarded fishing gear or with plastic debris in their stomachs.

Disease: Fibropapillomatosis (a tumour-causing disease linked to degraded foraging habitats) is an increasing concern.

Light pollution: Artificial lighting near beaches can disorient hatchlings, drawing them inland rather than toward the ocean.

Internationally, the species is listed under CITES Appendix I, prohibiting trade in wild-caught specimens. Within the archipelago, they are fully protected by the Galapagos National Park, which also monitors nesting activity and supports research through the Plastic Pollution Free Galapagos programme.

Where and When to See Them

Green turtles can be seen year-round throughout the Galapagos Marine Reserve. Around December to March, pregnant females are often visible near beaches, waiting for the cover of darkness to nest.

They are frequently observed by our guests on snorkelling excursions and boat safaris, surfacing quietly beside the hull or gliding through coral reefs and mangrove shallows. In these moments, their ancient lineage and effortless grace leave a lasting impression on all who encounter them.

Fast Facts

Scientific name: Chelonia mydas agassizii

Average lifespan: 80 years

Adult weight: 65–136 kg

Carapace length: up to 1.3 m

Diet: Marine algae and seagrasses (primarily herbivorous)

Status: Endangered (IUCN)

Protection: Galápagos National Park & CITES Appendix I