Melon-headed whales have a triangular, relatively narrow head, in which only females and young have a beak, albeit short and poorly defined. The triangular, sickle shaped dorsal fin is tall, reaching up to 30 cm. The body of the melon-headed whale is generally charcoal gray to black, with white lips and a white urogenital patch. On larger animals the black triangular "mask" on the face of melon-headed whales distinguishes them from the more uniformly-colored pygmy killer whales. Melon-headed whales also have a cape that dips below the dorsal fin, although its margin is often faint.
These animals have 20-25 small slender teeth in each tooth row. Melon-headed whales reach a maximum of about 2.75 m. Length at birth is thought to be about 1 m or less. Maximum known weight is about 275 kg.
Can be Confused With
At sea, melon-headed whales are often difficult to distinguish from pygmy killer whales. Major differences are that the melon-headed whale has pointed flippers and larger numbers of smaller teeth (pygmy killer whales have rounded flippers and only 8-13 pairs of more robust teeth.) Head shape, flipper shape, and the sweep and distinctness of the cape can be useful in identification. False killer whales can also be confused with this species at a distance.
The range of the melon-headed whale coincides almost exactly with that of the pygmy killer whale in tropical/subtropical oceanic waters between 40°N and 35°S.
In the Atlantic Ocean, melon-headed whales have been sighted on the mid-Atlantic coast of the United States, in the Gulf of Mexico, in the Caribbean, the coast of Brazil, and on the coast of Africa to Cape Good Hope.
In the Pacific Ocean, melon headed whales have been seen along the coast of Central and South America on the coast of Baja California, in the Gulf of Panama, and on the coast of Peru; in the eastern tropical Pacific and near the Hawaiian Islands; in the waters near Japan, the Philippines, and Indonesia; and on the Australian coast of Queensland and New South Wales.
In the Indian Ocean, melon-headed whales are found near the coast of Africa; in the Arabian Sea; on the coast of India and Sri Lanka; and in the Bay of Bengal.
Ecology and Behavior
Melon-headed whales inhabit shelf/slope waters and are highly social, and are known to occur in pods of 100-500 (with a known maximum of 2,000 individuals). They are often seen swimming with other species, especially Fraser’s dolphins in the eastern tropical Pacific and Philippines. Melon-headed whales often move at high speed, porpoising out of the water regularly, and are eager bowriders in many areas, often displacing other species from the bow wave. There is some evidence indicating a calving peak in July and August, but this is inconclusive. Little else is known of the species’ reproductive biology.
Feeding and Prey
Melon-headed whales feed by seizing prey, consisting of a diet dominiated by several species of squid > small fish.
Known prey species include invertebrates such as: Dosidicus gigas, Enoploteuthis sp., Teuthowenia sp., Abraliopsis sp., Bathyteuthis abyssicola
Threats and Status
Main threats of melon-headed whales include:
• Fisheries bycatch
The IUCN does not list the melon-headed whale as threatened or endangered, nor does the United States government. Although no large kills are known, melon-headed whales have been taken in various fisheries. This includes direct killing in drive fisheries in Japan and harpoon/driftnet fisheries in the Caribbean, Sri Lanka, the Philippines, and Indonesia, as well as incidental catches in tuna purse seines in the eastern tropical Pacific. This species is relatively common in some areas of its range, such as parts of the Philippines. The population in the eastern tropical Pacific was estimated in the early 1990’s to be ~45,000 individuals. In 1995, NMFS estimated the Gulf of Mexico population to be 3,965 (CV = 0.39), and the Hawaiian Islands population was estimated in 2000 to be 154 animals (CV = 0.88), although this number is thought to underestimate the population due to survey inadequacies.
Jefferson, T.A. and N.B. Barros. 1997. Peponocephala electra. Mammalian Species 553:1-6.
Miyazaki, N., Y. Fujise and K. Iwata. 1998. Biological analysis of a mass stranding of melon-headed whales (Peponocephala electra) at Aoshima, Japan. Bulletin of the National Science Museum, Tokyo 24A:31-60.
Perryman, W.L. 2002. Melon-headed whale Peponocephala electra. pp. 733-735 in W.F. Perrin, B. Würsig and J.G.M. Thewissen, eds. Encyclopedia of marine mammals. Academic Press.
Perryman, W.L., D.W.K. Au, S. Leatherwood and T.A. Jefferson. 1994. Melon-headed whale Peponocephala electra Gray, 1846. pp. 363-386 in S.H. Ridgway and R. Harrison, eds. Handbook of marine mammals, Volume 5: The first book of dolphins. Academic Press.
Wade, P.R. and T. Gerrodette. 1993. Estimates of cetacean abundance and distribution in the eastern tropical Pacific. Report to the International Whaling Commission. 43:477-493
Waring, G.T., J.M. Quintal and S.L. Schwartz. 2001. U.S. Atlantic and Gulf of Mexico marine mammal stock assessment – 2001. U.S. Department of Commerce, NOAA technical memorandum, NMFS-NE-168.
Watkins, W.A., M.A. Daher, A. Samuels and D.P. Gannon. 1997. Observations of Peponocephala electra, the melon-headed whale, in the southeastern Caribbean. Caribbean Journal of Science 33:34-40.