The feeding behavior and the food preference was studied in P. expansa (Schweigger, 1812) P. unifilis (Troschel, 1848) and P. sextuberculata (Cornalia, 1849). The method used for feeding behavior and food preference was the sampling of all occurrences. The Students' t test was applied on the food items, to compare differences during the development of each species. The main conclusions are: feeding behavior for food, except alive animals, is divided in foraging, approach, olfactory recognition, capture, laceration and ingestion; the persecution behavior was observed for prey activity; cleptoparasitism occurs in the three species and neustophagia mechanism was detected in P. unifilis; P. sextuberculata shows to be almost only carnivorous and P. expansa and P. unifilis show to be omnivorous; P. expansa can be considered more herbivorous in captivity than P. unifilis during the age between one and five years old and more than five years old; P. expansa is more sensitive than P. unifilis concerning the alteration of the food place, mainly the meat, decreasing its consumption, if it is put on a dry place.

Since 1985 the biology and behavior of Phrynops hilarii (Duméril & Bibron, 1835) at São Paulo Zoo is being studied. Feeding behavior is divided in five phases (foraging, approach, capture, dilaceration and ingestion), but not necessarily all of them happen. During phase 1 the food or prey seems to be visually located. During phase 2 the food itens and stationaty preys are approached and examined by olfaction. Moving preys are pursued and there is no olfactory examination. During phase 3 the food is captured by suction. When food is bigger than turtle mouth it is dilacerated by one or both forefeet used alternately (phase 4). Ingestion is accomplished by gradual suction (phase 5). Intra and inter-specific cleptoparasitism was observed. Success in capture and ingestion of food seems not be dependent on species or size of the turtle. Adults, young, and hatchlings of P. hilarii are primarily carnivorous and vegetables were rarely eaten.

Artificial incubation of 558 eggs from 70 clutches of Trachemys dorbignyi (Duméril & Bibron, 1835) were performed at São Paulo Zoo during 1992 and 1993. Hatching occurred when eggs were incubated between 25 and 31.5oC. Incubation time varied from 54 (at 31.5oC) to 120 days (at 25oC), similarly to Trachemys scripla sspp. Hatchling used the caruncle to made small incisions in the egg shell, latter enlarged by movements of the head and forefeet. Hatching usually lasted from one to two days. Newborn's carapace and plastron showed their natural form few hours after the emergence from the egg shell. During the third or fourth week, caruncle usually disappeared, and yolk sac was completely absorbed. Average (x±sd) measures of newborn were 3.55±0.18cm of carapace length, 3.35±0.17cm of plastron length, and 10.73±1.36g of weight.

Phrynops geofroanus is a carnivorous side-necked turtle. Its feeding behavior is divided in foraging, approach, capture, dilaceration and ingestion, but not necessary all these phases happen. Location of food seems to be visual and recognition olfactory. When food is an agile prey approach is done by pursuing and there is no olfactory recognition.