Omura's whale or the dwarf fin whale (Balaenoptera omurai)

Omura’s whale or the dwarf fin whale (Balaenoptera omurai)

At the end of last month (October 2015), marine researchers in the Indian Ocean captured the first ever moving images of Omura’s whale (Balaenoptera omurai) a “dwarf” rorqual about which very little is known.  I put “dwarf” in quotation marks because Omura’s whale is still a rorqual, a family which includes the largest animals to have ever lived. Adult Omura’s whales range in length from 9.6 to 11.5 meters (31.5 to 37.7 feet)—not exactly a miniature animal.

The whale is mysterious because it is rare.  The specimens which were observed (or killed) were thought to be a small subspecies of Bryde’s whale.  Only in 2003 did Japanese cetologists demonstrate incontrovertibly that the whale was a separate species (largely through genetic evidence preserved from specimens taken in infamous hunts/research expeditions).

An Omura's whale underwater lunge feeding (photo by  Cerchio et al. 2015, Royal Society Open Science)

An Omura’s whale underwater lunge feeding (photo by Cerchio et al. 2015, Royal Society Open Science)

Insomuch as we know anything about it, the Omura’s whale (which is named in honor of a famous Japanese whale scientist) is like other rorquals.  It is a huge pelagic filter feeder which captures plankton or small fish and invertebrates in its great baleen mouth and strains the water out.  It superficially resembles Bryde’s whale, however DNA reveals that it is an early offshoot from the rorqual lineage (its skeleton also differs greatly from Bryde’s whale)

We didn’t even know this was a species until 12 years ago—which illustrates how vast and unknown our own oceans still are. The Omura’s whales in the video/film were spotted in the Indian Ocean off the coast of Madagascar.  Hopefully they are not as isolated as they seem and the oceans will continue to be graced by this mysterious creature far into the future.

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