Sawsharks use their snouts to scrape up critters from the seafloor, while cookiecutter sharks take circular bites out of whales and other large creatures. Bottom-feeding sharks, like carpet sharks ...

Typically, pelagic sharks that never encounter the bottom are adapted to swim all their lives. But the vast majority of sharks have a buccal (mouth) pump and are not so-called "obligate ram ...

At that point, during the Cretaceous period, sharks were bottom dwellers, living in the depths of the ocean. But a massive outpouring of volcanic lava sent carbon dioxide levels soaring, ...