Deraniyagala’s beaked whale has never been seen, let alone studied, alive in the ocean.
This entire whale species is known from only seven dead whales that have stranded on remote tropical islands in the Indian and Pacific Oceans over the past 50 years. A Sri Lankan scientist named Mr Deraniyagala’s first named this enigmatic species in 1963 when he recognised it as a new beaked whale from a single female found stranded and dying on a beach near Colombo in Sri Lanka. Soon afterwards, it was wrongly grouped together with an existing rare beaked whale species (Ginkgo-beaked whale) and the Sri Lankan name was dropped. Then, 51 years later, a genetic study carried out in 2014 confirmed that Deraniyagala’s beaked whale is indeed a unique species and the whale has regained its original name.
IUCN conservation status: Data Deficient
What do Deraniyagala’s beaked whales look like?
They are small beaked whales growing up to less than 5m in length. The body is blue-grey coloured and typically for beaked whales, spindle-shaped. The head is small and tapered. Inside the mouth Deraniyagala’s beaked whales have only one pair of large and unusually- shaped tusk-like teeth.
There do not appear to be numerous white tooth-rake scars on the body that are commonly found on other beaked whales. It could be that the males do not fight over females using their teeth as is thought to be the case for other beaked whales. The dorsal fin is small and set two-thirds of the way back. The flippers are short and narrow; they slot into ‘flipper pockets’ on their sides for streamlined diving.
What’s life like for a Deraniyagala’s beaked whale?
Very little is known of Deraniyagala's beaked whale’s distribution, abundance, and biology because this whale is only known from seven individuals that have become stranded on the beaches of remote equatorial islands.
Even though Deraniyagala’s beaked whales have not been studied in the wild, we can deduce that, like all beaked whales, they make long dives to hunt squid in deep water and spend little time at the surface.
Scientists are unsure of how many Deraniyagala’s beaked whales exist; they have concluded that they must be either very rare and/or extremely elusive.
What do Deraniyagala’s beaked whale eat?
Most likely they eat deep-water squid as other beaked whales do.
Where do Deraniyagala’s beaked whale live?
There are no reports (yet!) of Deraniyagala’s beaked whales seen in offshore waters. It is possible that unlike some beaked whales, Deraniyagala’s beaked whale lives close to the shores of equatorial oceanic islands in the tropical Indian and Pacific oceans. Their distribution would be very patchy if this is true. Scientists have made acoustic recordings and seen beaked whales near Palmyra Atoll, in the Line Islands, in the central Pacific Ocean. They have speculated that these could well be Deraniyagala’s beaked whales.
What's in a name?
The ‘hotaula’ part of the Deraniyagala’s beaked whale’s scientific name comes from Sri Lankan words meaning 'pointed beak'. This whale is the only marine mammal with a Sri Lankan name.
How do you discover a new whale species?
In 2014, Deraniyagala’s beaked whale was established once and for all as a unique beaked whale species and the running total of beaked whales discovered so far became 22.
Several beaked whale species are known from only a handful of strandings and scientists predict that more of these rare and mysterious beaked whale species will be discovered in the future.
The important genetic study of Deraniyagala’s beaked whale was carried out on samples taken from seven strandings of which have occurred over the last 50 years in five regions of the tropical Indian and Pacific Oceans: Sri Lanka (one female whale stranding), Gilbert Islands, Republic of Kiribati (one or more whales represented by dried meat), Palmyra Atoll, Northern Line Islands, USA, Maldives, and Seychelles.
Scientists used a combination of DNA analysis and physical characteristics to identify Deraniyagala’s beaked whale as a new species from these seven specimens. However, they were only able to get good quality DNA from tissue samples from one of the specimens. For the others, they drilled the bones of the whales in order to analyse 'ancient DNA' and relied on scientific techniques commonly used for fossil material from extinct species.
Deraniyagala’s beaked whale need your help
The main threats...
- Whaling – Deraniyagala’s beaked whales are killed in traditional subsistence hunting in the Gilbert Islands – this has been discovered through talking to local people and recovery of whale bones.
- Noise pollution – Like other beaked whales, Deraniyagala’s Beaked Whales are likely to be vulnerable to loud man-made sounds, such as those generated by military sonar and seismic surveys.