Olive Ridley Sea Turtle
Lepidochelys olivacea

Habitat and Biology:

illustration: M. Demma © ICRAM

Typical habitats: Neritic, floating and feeding at the surface but also reported diving to 200m. Migrations: Along continental shelves, in some populations for several thousand miles between feeding and breeding grounds

Photo: Bates (Mexico )

Nesting areas:

• Beaches chosen have slight slopes, are isolated, often beyond protective lagoons.

Nesting periods:

• Year round in Mexico but principally in summer to late Autumn

illustration: M. Demma © ICRAM

Nesting behaviour: Females congregate in huge numbers 5,000 - 150,000 offshore, to nest during the final quarter of each moon, a phenomenon known as arribazones, arribada, morrinas or flotas. Most turtles nest during the night. On land, foreflippers moved alternately: hind flippers moved together or alternately. Advantages of arribazones: The saturation strategy of producing vast numbers of eggs and hatchlings at one time overwhelms predators, but leads to severe mortality because of disturbance of nests by other females : this is heaviest of short beaches. Most (60%) nest every year and lay more than once during the season. Average 1.5 times per year. Females show site fidelity (return to the same beach)

Egg number, size and weight:

• Clutch-size mean 109; range 20-155 with regional differences.
• Egg size : mean diameter 32.1-44.7 mm; mean mass : 30-38 g

illustration: M. Demma © ICRAM

Size and weight of hatchlings: Length SCL 34.7-44.6 mm Mass 12-22.3 g

Incubation time:

• 45-65 days being slower where the temperature and humidity vary from 30C and 14% respectively. Also varies with location, month and beach conditions.

illustration: M. Demma © ICRAM	Maturity: Age uncertain; size as little as 49 cm SCL
illustration: M. Demma © ICRAM	Courtship and Mating: No data Sex determination: 1:1 male to female at 30C bias to males at 28C bias to females at 32C Hatching: No data

Hatchling mortality and predation:

• Affected by human activity, weather conditions, predation and disease.
• They suffer heavy casualties following emergence, particularly if this occurs during the day.
• Eaten by a wide range of predators, from frigate birds to racoons, from ghost crabs to dogs.
• At sea, smaller turtles eaten by fish, particularly by sharks.

Feeding:

Fish	Molluscs	Crustaceans	ascidians	coelenterates	bryozoans
All illustrations (except first left): M. Demma © ICRAM

• Mostly in shallow water on a wide range of animal prey.
• Facultative carnivores, perhaps specialising where one prey species is easily available eg red lobsterets (Pleuroncodes planipes) on West Coast of California.
• Studies off Mexico show a very wide diet including fish, molluscs, crustaceans, ascidians, coelenterates and bryozoans.
• Some of these are benthic others nectonic.