New dolphin species
Identified by DNA tests, the new mammals were right under researchers ' noses.
A previously unknown species of dolphin has been identified in Australia. One of only three new dolphin species found since the 1800s, the Burrunan dolphin has been named after an Australian Aboriginal phrase that means ‘large sea creature of the porpoise kind'. Only two populations have been discovered so far, both of them in the state of Victoria. Around a hundred have been located in Port Phillip Bay, a built-up area very close to Melbourne, Australia's second most populous city, while another fifty are known to frequent the saltwater coastal lakes of the rural Gippsland region, a couple of hundred miles away.
It's long been known that distinct dolphin populations roam off south-eastern Australia. But now DNA tests have shown that these dolphins are genetically very different from the other two local species, the common bottlenose and the Indo-Pacific bottlenose. The results were so surprising that the team initially thought there was a mistake and reran the tests. As Kate Charlton-Robb, a marine biologist at Monash University, says: ‘The main focus of our research was to figure out which of the two known bottlenose species these dolphins belonged to. But from the DNA sequences that we got, it turned out that they were very different from either of them.'
The team also examined dolphin skulls collected and maintained by Australian museums over the last century, and determined that Burrunan dolphins have slight cranial differences that sets the species apart. And there are other observable differences too, such as the Burrunan's more curved dorsal fin, stubbier beak, and unique colouring that includes dark grey, mid-grey and white.
So how did the dolphins escape researchers' notice for so long? Physical variations in dolphins in south-eastern Australia have been reported for decades, though the new study is the first to use multiple lines of evidence to make a strong case for a distinct species. In fact, the Burrunan dolphin was almost discovered as far back as 1915, when a biologist captured and examined two very different dolphins from Australian waters. Scientists at the time concluded that both the animals were common bottlenose dolphins, and that their differences were due to one being male and the other female. After reviewing the female dolphin's skeleton recently, though, Charlton-Robb's team determined she was a Burrunan.
Because so few individuals belonging to the new dolphin species have been identified, the research team has petitioned the Australian government to list the animals as endangered. ‘Given the small size of the population,' Charlton-Robb says ‘it's really crucial that we make an effort to protect them.'