Marine Ecology

Short-finned pilot whale

May 2, 2011, 10:59 am
Content Cover Image

Short-finned pilot whale. Source: Alice Mackay/NOAA

The short-finned pilot whale (scientific name: Globicephala macrorhynchus), a marine mammal, is a a member of the family Delphinidae (Dolphins and Porpoises), part of the order of cetaceans. The pilot whale is so named because when swimming, the groups of about 15 to 20 individuals are often led by a single whale, the pilot.

Because of its gregarious nature and ability to be easily trained, this species is often brought into captivity.  In fact, the pilot whale has been trained by the US Navy to find lost military equipment at very great depths in the ocean.

Like its brother species, the Long-finned pilot whale, this species has a highly specialized function on its skin.  In order to keep microorganisms and other barnacles from growing on their skin, these two species secrete an enzymatic gel. This gel acts to break down any carbohydrates or proteins (the backbones of microorganisms) before microorganism colonies can begin to establish.

caption Short-finned pilot whale postage stamp.

caption Short-finned pilot whale size relative to human. Source: Chris Huh/Wikipedia

 Conservation Status
Data Deficient

Scientific Classification

Kingdom: --Animalia (Animals)
Phylum:--- Chordata
Class:------ Mammalia (Mammals
Order:-------- Cetacea (Cetaceans)
Family:-------- Delphinidae (Porpoise)
Genus:---------- Globicephala
Species:----------- Globicephala macrorhynchus Gray, 1846

Common Names
Blackfish
Bubble
Indian pilot whale
North Pacfic blackfish
North Pacific pilot whale
Pacific pilot whale
Shortfin Pilot Whale
Pothead
Short-finned pilot whale

Physical description

Unlike all other genera in the dolphin family, these whales have a specialized function. The skin of pilot whales resists microorganisms thanks to microscopic pores and nanoridges, surrounded by a secreted enzymatic gel which denatures proteins and carbohydrates.

Reproduction

Pilot whales are polygynous, which means that one male has more than one female mate.  In breeding groups, there is a ratio of about eight breeding females to one breeding male.  Males have been known to compete for females using aggressive behavior.

Females reach sexual maturity at seven to twelve years,  and males at 15 to 22 years of age.  The breeding season is spread across the year, however, it most commonly takes place in the winter.  Gestation lasts 11-13 months, and one calf is born.  Weaning occurs at an average of 2 years, although it has been known to extend to 6 or even 10 years (these longer periods are found in older mothers).  Usually, a maximum of 4-5 calves are born in a mother's lifetime.   Female reproduction slows after about age 28 years and stops after age 40 years.

Behavior

Individuals aggregate in groups of 15 to 20, with all ages and both sexes, although groups of several hundred have been reported. While swimming, the group is led by the pilot, and the rest of the pod follows by the signals of the pilot. When resting, pilot whales float stationary at the surface with their heads and dorsal fins exposed. Dives of 600 meters have been reported. Pilot whales are known to migrate from cold to warm waters.

Pilot whales are very communicative, and like other dolphins, they use echolocation.  These dolphins have been known to produce noises such as squealing, whining, snores, loud smacking, and whistling for communication.

In captivity, pilot whales survive well and are easily trained.  Interestingly, They have been trained by the US Navy to locate military equipment from deep ocean depths for retrieval.

Distribution

These animals are found in deep waters, typically in highest densities over the outer continental shelf or continental slope.  They occur in tropical to cool temperate waters. In 1982-83, a strong El Niño event brought about major ecosystem changes off the southern California coast. Pilot whales avoided the area (presumably due to the absence of spawning squid) for much of the next ten years.  This dolphin exists throughout tropical and warm temperate oceans all over the world in various countries including: Comores, Eritrea, Kenya, Madagascar, Mauritius, Mediterranean Sea, Mozambique, North West Atlantic, Reunion, Seychelles, Somalia, and Tanzania.

caption Distribution of the short-finned pilot whale in the world. Source: IUCN

Habitat

The Pacific, or short-finned, pilot whale lives throughout the tropical and warm temperate waters of several oceans and associated seas and bays.  Also, these dolphins are known to migrate from cold to warm waters.

Feeding habits

This species feeds on vertically migrating prey, with deep dives at dusk and dawn following vertically migrating prey and near-surface foraging at night.  On average, the pilot whale consumes about 45 kg of food each day.   The main component of their diet is squid, although small fish are sometimes eaten.  In particular, short-finned pilot whale teeth are reduced in size, typical of other squid-eating cetaceans.

Conservation status

Pilot whales are conservation dependent, and may be functionally extict in areas such as Newfoundland, but there are still sufficient numbers to support healthy populations of this species.  This dolphin is listed as Data Deficient on the IUCN Red List.

Threats

Before international whaling laws were enacted, pilot whales were heavily hunted in the Faroe Islands and Japan for meat and oil.  In fact, kills of over 10,000 a year were reported by Japan, and over 100,000 in 300 years (1584-1883) in the Faroe Islands.

In the Philippines, the pilot whales are taken by hand harpoons or, increasingly, by togglehead harpoon shafts shot from modified, rubber-powered spear guns.  Dolphin meat is consumed or sold in local markets and some dolphin skulls are cleaned and sold as curios.  Although takes and possession were banned in December 1992, the ban did not halt dolphin and whale hunting, however, the sale of dolphin meat openly in the market seems to be declining.

This species, like beaked whales, is likely to be vulnerable to loud anthropogenic sounds, such as those generated by navy sonar and seismic exploration. While conclusive evidence of cause and effect are often lacking, mass stranding events have been spatially and temporally associated with high levels of anthropogenic sound for short-finned pilot whales.

References and further reading

  • Encyclopedia of Life. Globicephala macrorhynchus Gray (1846) Short-finned pilot whale
  • Mammals of Texas. Short-finned Pilot Whales
  • IUCN
  • Globicephala macrorhynchus Pilot whale
  • Banks, R. C., R. W. McDiarmid, A. L. Gardner, and W. C. Starnes. 2003. Checklist of Vertebrates of the United States, the U.S. Territories, and Canada
  • Banks, R. C., R. W. McDiarmid, and A. L. Gardner. 1987. Checklist of Vertebrates of the United States, the U.S. Territories, and Canada. Resource Publication, no. 166. 79
  • Borges, P.A.V., Costa, A., Cunha, R., Gabriel, R., Gonçalves, V., Martins, A.F., Melo, I., Parente, M., Raposeiro, P., Rodrigues, P., Santos, R.S., Silva, L., Vieira, P. & Vieira, V. (Eds.) (2010). A list of the terrestrial and marine biota from the Azores. Princípia, Oeiras, 432 pp.
  • Felder, D.L. and D.K. Camp (eds.), Gulf of Mexico–Origins, Waters, and Biota. Biodiversity. Texas A&M Press, College Station, Texas.
  • Foote (2008) Mortality rate acceleration and post-reproductive lifespan in matrilineal whale species. Biol Lett, 4:189-191.
  • Gewalt, W. 1990. Killer Whales and Pilot Whales. Pp. 387-397 in S. Parker, ed. Grzimek's Encyclopedia of Mammals, Volume 4. New York: McGraw-Hill Publishing Company.
  • Gordon, D. (Ed.) (2009). New Zealand Inventory of Biodiversity. Volume One: Kingdom Animalia. 584 pp
  • Gray, J. E., 1846. On the cetaceous animals. Pp. 13-53, in The zoology of the voyage of H.M.S. Erebus and Terror, under the command of Capt. Sir J. C. Ross, R. N., F. R. S., during the years 1839 to 1843 (Sir J. Richardson and J. E. Gray, eds.) [1844-1875], 1:33. E. W. Janson, London, 2 vols.
  • IUCN (2008) Cetacean update of the 2008 IUCN Red List of Threatened Species.
  • Jefferson, T.A., S. Leatherwood and M.A. Webber. 1993. Marine mammals of the world. FAO Species Identification Guide. Rome. 312 p.
  • Longevity Records: Life Spans of Mammals, Birds, Amphibians, Reptiles, and Fish (Online source)
  • Mead, James G., and Robert L. Brownell, Jr. / Wilson, Don E., and DeeAnn M. Reeder, eds. 2005. Order Cetacea. Mammal Species of the World: A Taxonomic and Geographic Reference, 3rd ed., vol. 1. 723-743
  • Minasian, S., K. Balcomb, L. Foster. 1984. The World's Whales: The Complete Illustrated Guide. Washington, D.C.: Smithsonian Books.
  • North-West Atlantic Ocean species (NWARMS)
  • Nowak, R. 1999. Walker's Mammals Of The World. Baltimore: Johns Hopkins University Press.
  • Perrin, W. (2010). Globicephala macrorhynchus Gray, 1846. In: Perrin, W.F. World Cetacea Database. Accessed through: Perrin, W.F. World Cetacea Database at http://www.marinespecies.org/cetacea/aphia.php?p=taxdetails&id=137096 on 2011-02-05
  • Ramos, M. (ed.). 2010. IBERFAUNA. The Iberian Fauna Databank
  • Rice, Dale W. 1998. Marine Mammals of the World: Systematics and Distribution. Special Publications of the Society for Marine Mammals, no. 4. ix + 231
  • UNESCO-IOC Register of Marine Organisms
  • Wilson, Don E., and DeeAnn M. Reeder, eds. 1993. Mammal Species of the World: A Taxonomic and Geographic Reference, 2nd ed., 3rd printing. xviii + 1207
  • Wilson, Don E., and F. Russell Cole. 2000. Common Names of Mammals of the World. xiv + 204
  • Wilson, Don E., and Sue Ruff, eds. 1999. The Smithsonian Book of North American Mammals. xxv + 750
  • van der Land, J. (2001). Tetrapoda, in: Costello, M.J. et al. (Ed.) (2001). European register of marine species: a check-list of the marine species in Europe and a bibliography of guides to their identification. Collection Patrimoines Naturels, 50: pp. 375-376

 

Glossary

Citation

Life, E. (2011). Short-finned pilot whale. Retrieved from http://www.eoearth.org/view/article/156004

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