The mysterious Omura’s whale

At the end of October, an international team of biologists released the first ever footage taken of the Omura’s whale (Balaenoptera omurai), filmed off the coast of Madagascar.

An Omura’s whale (Salvatore Cerchio, Woodhole Oceanographic Institute)

Until 2003, the Omura’s whales were misidentified as a pygmy form of the Bryde’s whale; a baleen whale known to live all year in equatorial, warm waters. Previously, only a few whales (12 or so) have been genetically confirmed as Omura’s whales and these were either stranded whales or whales killed during legal whaling operations in the 70’s  for Bryde’s whales (IUCN, 2015).

Bryde's whale - Jirayu Tour Ekkul

The Bryde’s whale which the Omura’s whale was mistaken for many years (UKwhales.org)

These whales may be the most conspicuous mammals in the oceans but they aren’t small. Males reach the maximum length of 10 m and females 11.5 m.  Omura’s whales belong to the group of whales called baleen whales; which means they have a long baleen plates (protein plates that hang in their mouth like a comb) and paired blow holes.

stylized baleen.jpg (9640 bytes)

Baleen plates (NOAA fisheries)

Omura’s whales are believed to have a slightly different body shape to other baleen whales but they do have similar colouration, including an asymmetrical jaw; white on the right side and dark on the left. They have 80 to 90 throat pleats that extend beyond the navel. The dorsal fin (one on top) is tall, curved like a sickle and positioned two thirds of the way down its back. The flippers are relatively long and the tail has an indistinct notch.

Very little is known about the behaviour and  distribution of Omura’s whales. From the few verified sightings it looks like these whales live relatively solitary lives by themselves or in pairs. Their throat grooves suggest that they are lunge feeders that predominately feed on school of fish, just like other, more well-known whales with throat grooves (humpback whales for example).

It is thought that they are found in the subtropical waters of the western and northwestern Pacific and eastern Indian Ocean. The size of the population is completely unknown. The lack of information on Omura’s whales increases the risk of negative effects from human activities, pollution and climate change, as we are unable to even attempt to protect them at the moment. However, this new sighting and footage is an exciting step forward for marine biologist and emphasises how much we still have to learn and discover about the marine world.

References:

UK whales: http://uk.whales.org/species-guide/omuras-whale and http://uk.whales.org/species-guide/brydes-whale

IUCN Red List: http://www.iucnredlist.org/details/136623/0

NOAA Fisheries: http://www.afsc.noaa.gov/nmml/education/cetaceans/baleen1.php

The Guardian: http://www.theguardian.com/environment/video/2015/oct/31/first-glimpse-rare-omuras-whale-madagascar-video

 

 

 

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Hannah Lawson

Hannah Lawson

I'm a marine biologist working as an Environmental Scientist for a marine consultancy. I love nature and the marine environment. I try to spend as much of my spare time outside and getting involved with conservation and outdoor activities.
Hannah Lawson

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