Only officially recognized as a separate species in 2003, very little is known about Omura’s whales. For decades, the few individuals caught were misidentified as “pygmy” or “dwarf” Bryde’s whales, as both live in the tropical waters of the Indian Ocean and have a very similar appearance. Even then, it was only known from around eight individuals caught by Japan in the 70s, and a handful that had washed up on beaches.
Now, however, researchers have been able to conduct the first-ever field observations of the rare and elusive whales, not in the waters of the Far East where it was first reported, but on the opposite side of the Indian Ocean off the island of Madagascar. They have been able to observe the animals on 44 occasions, allowing them to describe the whales’ feeding, vocal and possible breeding behaviors. They’ve also been able to determine the cetaceans’ habitat preference – thought to be shallow coastal waters – and collect video footage of the whales.
“Over the years, there have been a small handful of possible sightings of Omura's whales, but nothing that was confirmed,” explained Salvatore Cerchio, the lead author of the study published in the Royal Society Open Science journal. “They appear to occur in remote regions and are difficult to find at sea because they are small – they range in length from approximately 33 to 38 feet [10 to 11.5 meters] – and do not put up a prominent blow.”
Photos showing the unique colorations of Omura's whale. Cerchio et al.
The cetacean is a member of the group of whales called rorquals, which also includes the largest of them all, the blue whale. Members of this group feed using what are known as “baleen plates,” which are effectively large combs that filter out small crustaceans and fish from the water. The process is aided by the characteristic parallel grooves that run from the mouth down to the navel of the whales, which allow the mouths of the animals to expand massively.
So little information is known about the whales that their numbers and range still remain unknown, with the IUCN designating them as “data deficient.” This is probably down to the continued misidentification of the animals, as even the team who have been studying them in Madagascar originally thought they were the larger Bryde’s whale. It was only when they noticed the odd coloration – Omura’s have unique markings where the right side of the lower jaw is white, but the left side is dark – and the smaller size that they suspected they were actually looking at Omura’s.
The researchers want to return to the waters off Madagascar and continue studying the whales, collecting more data on their vocalizations and behavior, and hopefully building a detailed picture of their population, as well as using acoustics to see if they can find the elusive cetaceans in other parts of the ocean.
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