Researchers analyzing echolocation signals off Antarctica might have identified one—and maybe even two—brand new species of beaked whales. Beaked whales are a little known group of whales that are very rarely observed. These whales resemble giant dolphins both in appearance and in their use of echolocation to identify their prey.

Beaked whales dive frequently and live in open water, so they are very rarely observed at the surface. The limited knowledge means researchers are uncertain if the signal really is from an unknown species, or whether a known species has the rare ability to make multiple sounds.

What else is known about these mysterious cetaceans? Until recently, practically all that was known about beaked whales came from stranded specimens and the rare sighting by a mariner. In recent years, small numbers of beaked whales have been tagged, providing limited information about their habits.

Beaked whales regularly take dives to nearly 2000 meters and remain at those depths for an hour or more. During dives of such extraordinary depth and duration the whales stop using oxygen and rely on anaerobic respiration, a highly inefficient process. In order to make this type of respiration worthwhile the whales must lower their metabolism.

Beaked whales have refined this process to such an extent that of the deepest-diving mammals, most are beaked whales, a number that may increase as more is learned about them. Unfortunately, these whales have been stranding themselves in greater numbers, possibly victims of submarine sounds produced during naval maneuvers. Pending further confirmation, all that can be said for sure is that even in the ocean, it pays to keep your ears open. With so little known about these elusive creatures, who knows what else they’re capable of?