Tropical bottlenose whale

The tropical bottlenose whale (Indopacetus pacificus), also known as the Indo-Pacific beaked whale and the Longman's beaked whale, was considered to be the world's rarest cetacean until recently, but the spade-toothed whale now holds that position. As of 2010, the species is now known from nearly a dozen strandings and over 65 sightings.

The Longman's beaked whales look rather similar to both mesoplodont beaked whales and bottlenose whales, which led to a great deal of taxonomic confusion. The Maldives female had a robust body like the bottlenoses, although this may be a distortion, since the less-decomposed female specimen from Japan had a laterally compressed body typical of Mesoplodon. The juvenile specimens have a very short beak similar to a bottlenose whale, but the adult females seen so far have had rather long beaks sloping gently into a barely noticeable melon organ. Additionally, the dorsal fins of adult specimens seem unusually large and triangular for beaked whales, whereas in juveniles they are rather small and swept back.

An adult male specimen has yet to wash up, but sightings of the tropical bottlenose whale indicate they have a rather bulbous melon, two teeth located towards the front of the beak, and scars from fighting with the teeth. Scars from cookiecutter sharks are also rather common on the whale. The rather unusual coloration of the juveniles helped connect the Longman's to the tropical bottlenose whale; both have dark backs behind the blowholes, which quickly shade down to a light gray and then white. The blackness from the back extends down to the eye of the whale except for a light spot behind the eye, and then continues on in a line towards the flipper, which is also dark.

Tropical bottlenose whale
  • Size

    The female specimen from the Maldives was six metres (20 feet) in length, with a one-metre (3 foot) fetus, and the Japanese female was 6.5 metres (22 feet) in length. Reports of tropical beaked whales put them even longer, in the 7–8 metre (23–26 foot) range, which is larger than any mesoplodont and more typical of a bottlenose whale. No weight estimation or reproductive information is known.

  • Feeding

    Dietary information is available from stomach contents analyses of stranded beaked whales and from whaling operations. Their preferred diet is primarily deep-water squid, but also benthic and benthopelagic fish and some crustaceans, mostly taken near the sea floor. In a recent study, gouge marks in the seafloor were interpreted to be a result of feeding activities by beaked whales

  • Life History

    Very little is known about the life histories of beaked whales.There are currently no data available on their reproductive rates.

  • Behavior

    Tropical bottlenose whale observations indicate they travel in larger groups than any other local species of beaked whales. The size of the pods range from the tens up to 100, with 15 to 20 being fairly typical, and the groups appear very cohesive. Their pods are sometimes associated with other species, such as short-finned pilot whales, bottlenose dolphins, and spinner dolphins.