Earlier this year, Vladimir Dinets—a University of Tennessee psychology professor who has spent 3,000 hours observing crocodiles and alligators—released a study revealing that crocodiles surf ocean waves for fun, young alligators repeatedly slide down slopes, and baby alligators go for rides on their older friends’ backs.

He also told the story of a crocodile who befriended a man who had saved his life. According to the professor, the crocodile and his human friend played every day until the crocodile’s death 20 years later. “The croc would swim with his human friend, try to startle him by suddenly pretending to attack him or by sneaking up on him from behind, and accept being caressed, hugged, rotated in the water and kissed on the snout,” said Dinets.

Here are some more fascinating facts about these prehistoric reptiles:

• Alligators and crocodiles are excellent mothers. They zealously guard their eggs from predators. Once the babies hatch, the mothers are drawn by their cries and carry them, one by one, to the water. Mother alligators use their jaws, as we would use our hands, to gently crack open their eggs and carry their babies.
• Alligators also communicate with one another through hisses, yelps, coughs, and other sounds, and crocodiles can recognize their names, as a pair of dwarf crocodiles at a facility in England have demonstrated.
• Researchers have found that the hundreds of dots along the jaws of alligators and crocodiles are sensory organs that are more sensitive to touch than human fingertips. At an alligator farm in Texas, many alligators’ sensitive jaws were covered with raw skin, which a manager admitted “hurts” them.