Where did it start? How did it grow complex? Why did it get big? Three moments in Earth’s early history when evolution suddenly, inexplicably turned up the dial.

An internal memo reinterprets the law so that only the intentional killing of animals, not collateral harm, is illegal.

Rising sea temperatures mean reefs don’t have enough time to bounce back between intense heat waves, a new report warns.

© Jason Gulley for The New York Times

A die-off of seabirds has some experts thinking an El Niño weather pattern is to blame, a look at data centers and pollution, and more climate news.

© American Bird Conservancy

Scientists in Mexico were the first to perform ultrasounds on giant manta rays to detect pregnancies. The researchers hoped to learn more about the life cycle of the largest ray species in the world.

Scientists managed to confirm pregnancies in three giant mantas with underwater ultrasound scans, offering clues to the animals’ elusive reproductive habits.

Transmissible tumors have been reported in a handful of animal species, but never before among fish. Is it possible in humans?

New research has identified areas around the world where cooler currents and other favorable conditions are helping to protect coral from the worst effects of global warming.

New research has identified areas around the world where cooler currents and other favorable conditions are helping to protect coral from the worst effects of global warming.

By tracking eye movements in zebrafish, researchers identified four different types of sleep, analogous to the complex sleep patterns of humans and other animals.