Little is documented about what preys on these turtles. As with most turtle species, eggs and hatchlings are likely the most vulnerable life stages. The months spent dormant underground during estivation could also expose buried turtles to predators. Adults benefit from the protection of their shells, and their ability to withdraw into burrows when ponds dry up probably offers additional safety. Leeches of the family Hirudidae parasitize this species, concentrating in the protected skin folds near the shell.

Rather than hibernating through cold winters, this species estivates—going dormant during dry periods when their wetland habitats shrink or disappear. When ponds begin drying up, individuals burrow into the ground, sometimes reaching depths of about 50 cm below the surface. They remain dormant underground until conditions improve, presumably emerging when rains return and refill their aquatic habitats.

Activity, movement, and habitat use all increase with rising air and water temperatures. The species is primarily nocturnal, though daytime activity has been observed, particularly during courtship and nesting.

These turtles are opportunistic feeders with a generalist diet. Insects make up the bulk of their meals, particularly aquatic insects which comprise more than half of their prey items. They also eat tadpoles, small fish, snails, and spiders. In captivity, they readily accept beef, fish, shrimp, and small frogs. Studies have found high dietary overlap between males and females, suggesting both sexes exploit similar food resources.

Reproductive timing varies across the range. In Brazil, the nesting season runs from February to May, while in Uruguay, breeding has been suggested to occur in August, with hatchlings commonly appearing from September through February. Observations in Brasília National Park recorded mating events between November and December during the rainy season.

Clutch sizes range from 4 to 8 eggs, with an average of about 5. The eggs are nearly spherical, measuring roughly 25–27 mm in length. Females dig shallow nests about 4 cm deep. Here's a remarkable quirk: this species may have the longest incubation period of any South American side-necked turtle—potentially 587 to 615 days, including a diapause (developmental pause) period. This extended incubation appears to be an adaptation to the unpredictable dry and rainy seasons of their South American habitat. Hatchlings emerge at 31–32 mm shell length and weigh approximately 5 grams.

The spiny tubercles studding the neck are the namesake feature—prominent cornified cones that give this turtle a distinctively rough-textured appearance unlike most other freshwater turtles. These spines, combined with the species' predominantly black coloration, make adults unmistakable within their range.

The dramatic color change from hatchling to adult is equally striking. Young turtles with their vivid red and orange markings look almost like different species compared to the uniformly dark adults. This transformation happens gradually over the first months of life.

The species' exceptional adaptability is another defining trait. Few turtles thrive equally well in pristine wetlands and urban parks, rice paddies, and roadside ditches. This flexibility has helped populations persist even as natural habitats disappear—though it also exposes them to threats like agricultural chemicals and road traffic.