The Omura's whale is a relatively small baleen whale about which very little is known. Before its formal description, it was referred to as a small, "dwarf" or "pygmy" form of Bryde's whale by various sources. Its appearance resembles the larger Fin whale (thus the alternate common names of Dwarf fin whale and Little fin whale), both having a dark gray left lower jaw, and on the right side a white mandible patch, a white blaze, a dark eye stripe, a white inter-stripe wash, as well as a white chevron on the back, pectoral fins with a white anterior border and inner surface, and flukes with a white ventral surface and black margins. Like fin whales, the Omura's whale also exhibits a white left gape and a dark right gape, a reversal of the asymmetrical pigmentation on the lower jaw.
Omura's whales are found in the Indo-Pacific and the Atlantic Oceans. Their range includes southern Japan, South Korea, China, Taiwan, Hong Kong, the Philippines, Vietnam, Malaysia, Thailand, Indonesia, the Cocos (Keeling) Islands, the Andaman Islands, Australia, the Solomon Islands, New Caledonia, Sri Lanka, the Chagos Archipelago, Iran, Egypt, northwestern Madagascar, Mauritania, Brazil and in the vicinity of Saint Peter and Saint Paul Archipelago. Omura's whales don't migrate and live in tropical and warm-temperate seas. They spend most of their time in shallow waters and rarely venture into deep waters.
Little is known about the behavior of Omura's whales. Their blow is low and diffuse. After surfacing, the dorsal fin is usually not visible until after the head and splashguard have disappeared and they don't fluke when diving. They usually travel alone or in pairs but loose aggregations of as many as a dozen whales could be seen. Omura's whales communicate with amplitude-modulated songs. They sing their melody on average within 9 seconds followed by a tonal call of 4 seconds in duration. These songs are repeated every two to three minutes, sometimes for as long as thirteen hours. Omura's whales may even sing their song in overlapping choruses.
Nothing is known about the reproductive habits in Omura's whales. Generally, gestation in baleen whales lasts 11-12 months, so that both mating and birthing occur at the same time of year. Cows give birth to a single calf, which is usually weaned after 6-12 months, depending on the species.
The main threats to Omura's whales include habitat loss due to pollution and noises, entanglement with fishing gears, and ship strikes.
Due to the WDC (Whale and Dolphin Conservation) resource, the total population size of the Omura's whale in the oceans is about 50,000 individuals. Currently, this species is classified as Data Deficient (DD) on the IUCN Red List site.