Previously it was thought humans were the only species to put on performances for the purpose of bonding and cooperation.
The whales were observed in the Northeast Canyons and Seamounts Marine National Monument, located around 130 miles east-southeast of Cape Cod, Massachusetts.
Police are offering a reward of up to $20,000 to anyone who shares information that leads to those responsible.
"You can see what looks like teeth marks and I just can't think of anything else that could have done this," a witness told British tabloid media. But experts say white sharks are not known in the region.
Report from World Animal Protection reveals cruel practices at aquariums and zoos around the world.
The fatal wound, located above the right eye, measured around 6 inches in length and penetrated through to the top of the skull.
Researchers investigated a unique group of dolphins in Western Australia which use sponges as tools to forage for food.
Below the surface, the oceans are not as quiet as you might think.
"There are few things more magical in this world than hundreds of dolphins racing through the wild Monterey Bay on a foggy fall morning."
Animals can accidentally ingest the toxic algae while feeding.
The whale's pod hasn't had a single viable pregnancy over the past three years.
Dolphin societies are surprisingly complex.
The sea mammals were being trained in a Soviet-era facility in Sevastopol that breeds marine assistants for the navy.
The dolphin is still in critical condition.
Technically, dolphins are whales, and whales are more closely related to cows than sharks.
The ancient marine mammal could help explain when North and South America first joined.
The annual dolphin slaughter is similar to American cattle slaughtering, said a representative.
Antonio Brown may have a case, too.
Dozens of species in the reserve cannot be found anywhere else in the world.