Black sea turtle
Chelonia agassizii

Habitat and Biology:

illustration: M. Demma © ICRAM	Typical habitats: Coastal waters, graze over shallow sandy flats. Sleeping shelters behind rocks or corals. Migrations: Sometimes swim North and South from the breeding grounds of Mexico, El Salvador and Galapagos.
Nesting areas: Where Chelonia agassizii shares beaches with Lepidochelys olivacea and Dermochelys coriacea, it nests after the first and before the second. It also nests higher above the high tide line.

Nesting periods:

• Season shifts in time with latitude.
• In the North - October to November
• In the South (Galapagos Islands) - February to March.

illustration: M. Demma © ICRAM

Nesting behaviour: Females show high fidelity to a nesting site, returning close to their first nest in subsequent emergences and years.

• There is a difference between Northern and Southern populations.
• On Michoacan (North), a female may lay 1 - 8 clutches per season (mean 2.8 per female) every 1, 2 or 3 years (mean 2.2 years): Clutch size - mean 70, (38 - 139 eggs).
• In the Galapagos (South), a female may lay 1 - 5 clutches per season; (mean 1.4 per female) every 2 to 5 years (mean 3.5 years): Clutch size - mean 81 (56 - 152 eggs).
• Egg size: mean diameter 41.6 mm (36.9 - 48 mm)

illustration: M. Demma © ICRAM

Size and weight of hatchlings: No data

Incubation time:

• Incubation time : 46 - 62 days (temperature dependent)

illustration: M. Demma © ICRAM

Maturity: Maturity at around 8 - 9 years

illustration: M. Demma © ICRAM

Courtship and Mating: Courtship: reports from 1976-79 describe mating pairs accompanied by up to a dozen other males. In recent years male numbers have fallen probably because of a fishing bias towards males. Sex determination: No data

Hatchling: Hatchling mortality and predation:

• Eggs eaten by a range of predators depending on location but include pigs, dogs, ghost crabs, a burrowing beetle, Tox suberosus in the Galapagos and in Michoacana by scavenger flies.
• Hatchlings eaten by predators such as dogs, pigs, birds, sea snakes and fish.
• Release of scent at pipping time from the nest attracts dogs, pigs and other predators.

• No data

Feeding:

Algae/seagrass	Molluscs	Sponges	Jellyfish	Mangrove shoots	Annelids	Tunicates
Illustrations (except second from right): M. Demma © ICRAM

• Essentially a herbivorous species, but hatchlings and juveniles feed on pelagic animals before moving inshore.
• Migrating adults feed on a wide range of invertebrates including molluscs, sponges, jellyfish, annelids and tunicates.
• Most graze on algae, sea grasses and mangrove shoots.