Black-bellied Slider

The gender of Trachemys dorbigni can be determined by the form of the plastron, which after a few years of life, shows differences between male and female. The males has a penis that is located in the tail and becomes apparent only during the mating season when it is inserted into the female's cloaca. D'Orbigny's slider has a life span of between 30 and 100 years in captivity. Hatchlings weigh 11 grams (0.39 oz) with a 3.5 cm (1.4 in) carapace. The average growth rate is about 3 cm (1.2 in) per year in the wild, but in captivity it can grow faster being able to grow over 9 cm (3.5 in) in a year. The female can grow up to 30 cm (12 in) straight-line carapace length and weigh over 2.7 kg (6.0 lb), while the male can only grow to 25 cm (9.8 in). When the male reaches sexual maturity (after 2 years), it acquires a dark color, while the female keeps the same green after maturity (at 5 years).

Sexual dimorphism. The sex identification is only possible when adult, at 5 or 6 years. The female is bigger and may reach 30 cm (12 in) in length and has the plastron (bottom shell) slightly convex so as to provide more space for eggs. The male reaches 20–25 cm (7.9–9.8 in) and has a longer and bulkier tail. …

Trachemys dorbigni is usually found in bodies of water such as lakes, marshes, streams and rivers. It has a preference for waters with low or moderate currents, soft bottoms and abundant aquatic vegetation.

The female Trachemys dorbigni produces an average of 10 eggs per buried nest; usually it buries two nests per season. Incubation ranges from 2 to 4 months. The eggs are laid under approximately 10 cm (3.9 in) of sand. The eggs are white-colored. Each egg on average measures 39.3 mm (1.55 in) in length and 25.8 mm (1.02 in) in width, weighing on average 14.9 g (0.53 oz). Only 31% of the female population lays eggs each year. The sex of baby turtles is determined by the temperature of the sand during incubation, lower temperatures increase the number of females.