Researchers believe they have found a previously unknown species of beaked whale in waters off Mexico's western coast. If confirmed, the new species would mark a significant discovery among giant mammals.

The team of researchers came upon three unusual specimens while tracking a different, rare species of typically shy beaked whales on November 17, near Mexico's remote San Benito Islands, about 300 miles south (500 km) of the US border. 

Jay Barlow, a marine mammal biologist at the Scripps Institution of Oceanography in San Diego, and his colleagues on the trip, led by the non-profit Sea Shepherd Conservation Society, did not realise they were seeing a potential new species until later when studying photos they took of the animals. 

The whales' teeth were unusually placed, Barlow reported. 

Underwater recordings of the whales' calls also suggested they were unique, he added. 

The scientists are now awaiting the analysis of water samples that could hold skin cells for possible DNA testing to confirm whether the whales are a new species, Barlow said 

Beaked whales - named for their pointy, dolphin-like snouts - are found mostly in remote waters, such as off the San Benito Islands. 

Though up to 5 metres (16.4 feet) long, they can be hard for scientists to observe as they tend to swim and feed mostly at depths of around 914 metres (3,000 feet), surfacing only occasionally for air. At such depths, the animals have a better chance of avoiding their main predator, killer whales. 

While determining a new species is a rare event, experts believe the findings described by Barlow's team seem consistent with a unique discovery. DNA testing would be needed to provide a conclusive answer, said Andrew Read, a marine biologist at Duke University. 

If confirmed, this discovery would bring the number of known beaked whale species to 24.