The dwarf sperm whale, or Kogia sim, is a smaller relative of the sperm whale. The species lives in warm waters around the world, feeding on fish, crustaceans and cephalopods. Dwarf sperm whales are shy and rarely stay near the ocean's surface, making them an elusive and difficult to study species. As a result, the impact of threats to the species, such as ships, nets, marine debris and pollution aren't fully known.
An adult dwarf sperm whale typically reaches lengths of 9 feet (2.7 m), and weighs between 300 and 600 lbs. (135-270 kg). Male dwarf sperm whales are generally larger than females. The dorsal fin located on the middle of the back varies in shape — some dwarf sperm whales have more triangular dorsal fins, while others have a curvy or pointed fin. Their skin coloring is a dark grayish-blue or brown with a light pink or white belly. The dwarf sperm whale's lower jaw is considerably shorter than the upper jaw, although the lower jaw contains more sets of teeth. The whales have a blowhole and spermaceti organ, which produces oil.
Dwarf sperm whales inhabit tropical and temperate ocean waters, living in several parts of the world, including the coastal waters surrounding Australia, Indonesia, South Africa and Chile. They're also found in the Gulf of Mexico, the Persian Gulf, British Columbia, Japan and California. The total population is unknown due to rare sightings of the species.
When dwarf sperm whales emerge on the surface of the sea, they do so singly or in small groups, keeping most of their bodies hidden underwater while they float. The elusive whales generally don't swim up to boats or approach people. They differ from other small whale species by dropping straight back down into the water without rolling over first.
Cephalopods such as squids and crustaceans such as crabs serve as the main sources of prey for the dwarf sperm whale, in addition to several types of fish. They dive to the bottom of the sea to hunt for food and use a suction technique to catch it.
Female dwarf sperm whales typically give birth to calves during the summer months. The calves weigh up to 110 lbs. (50 kg) and measure around 3 feet (1 m) in length. They're generally weaned at around 1 year of age.
Potential predators of dwarf sperm whales include great white sharks and killer whales. When threatened, the dwarf sperm whale shoots 3 gallons (or 12 liters) of a brownish-red liquid, creating an inky cloud that allows it to escape from predators. Human threats to this species include fishing nets, boats and sound and water pollution in the ocean. Additionally, fishermen in a few areas also hunt and kill them with harpoons. The Marine Mammal Protection Act seeks to reduce these threats through various measures.