Costa Rica crocodiles survive in 'most polluted' river

Every day, trash and wastewater from San Jose households and factories flood into the Tarcoles River, which vomits tires and plastic into the surrounding mangroves.

Nevertheless, some 2,000 American Crocodiles have adapted to life in the toxic river that bears witness to the country's decades-long battle with .

"It is a super-contaminated area, but this has not affected the crocodile population," said Ivan Sandoval, a biologist with the National University of Costa Rica.

"The Tarcoles River is the most polluted river in Costa Rica, and one of the most contaminated in Central America. Heavy metals, nitrites, nitrates, and a large amount of human waste can be found," added the crocodile expert.

According to the International Union for Conservation of Nature (IUCN), there are only about 5,000 of the crocodile species—found in 18 countries—left in the world after decades of hunting and .

The organization lists the Crocodylus acutus as "vulnerable," but says its numbers have increased in recent years. The Costa Rica population is "healthy and robust."

A crocodile swims amid garbage in the Tarcoles River, one of the most polluted in Central America. This species is thriving despite the toxic waters.

A crocodile lurks in the contaminated Tarcoles River, unphased by the toxic water.

View of the Tarcoles River, one of the most polluted in Central America, as it flows into the Pacific Ocean.

Birds perch amid garbage-strewn branches on the Tarcoles River.