Cetaceans

Humpback whale. Source: NOAA

Species (main)

Published: September 24, 2009, 12:00 am

Updated: June 13, 2013, 7:36 pm

Topics:

Species (main) Conservation Biology (main) Marine Ecology (main) Oceans and seas (main) Biodiversity (main) Zoology (main) Wildlife (main)

Cetaceans are marine mammals within the order of Cetacea, which includes whales, dolphins and porpoises. Unlike pinnipeds, these species spend their entire lives in aquatic media.

Northern right whale, Eubalaena glacialis, with calf. Source: Fish and Wildlife Conservation Commission/NOAA

Scientific Classification Kingdom: Animalia (Animals) Phylum:--- Chordata Class:------ Mammalia (Mammals) Order:-------- Cetacea Family:--------12 families of species

The number of recognized cetacean species has changed in recent years, with recent research revealing that certain populations are not one species as previously thought, but in fact two or more separate and distinct species.

Currently, the order Cetacea includes approximately 87-88 species in twelve families grouped under two sub-orders, Baleen whales (Mysticeti) and Toothed whales (Odontoceti).

Baleen whales are named for the long plates of baleen which hang in a row (like the teeth of a comb) from their upper jaws. Baleen plates are strong and flexible; they are made of a protein similar to human fingernails. Baleen plates are broad at the base (gumline) and taper into a fringe which forms a curtain or mat inside the whale's mouth. Baleen whales strain huge volumes of ocean water through their baleen plates to capture food: tons of krill, other zooplankton, crustaceans, and small fish.

Tragically, one cetacean, the Chinese river dolphin (Baiji), has not been sighted since 2002 despite extensive searches of its limited habitat, and is now believed to be extinct. The Gulf of California harbor porpoise (Vaquita) is critically endangered and the most endangered species of cetacean in the world (~567 individuals estimated in 1997). The North Atlantic right whale is also critically endangered and the most endangered large whale in the world (approximately 300 to 350 individuals in 2001).

Taxonomy

Baleen whales (Mysticeti) Balaenidae North Atlantic right whale North Pacific right whale Southern right whale Bowhead whale Humpback whale Northern Minke whale (Common Minke whale) Antarctic Minke whale Sei whale Bryde's whale Omurai's whale - Eden's whale (possible subspecies) Fin whale Blue whale Gray whale Pygmy right whale Toothed whales Delphinidae (Oceanic Dolphins) Commerson's dolphin Black dolphin (Chilean dolphin) Heaviside's dolphin Hector's dolphin Long-beaked common dolphin Saddle-backed dolphin (Short-beaked common dolphin) Pygmy killer whale Short-finned pilot whale Long-finned pilot whale Risso's dolphin Fraser's dolphin Atlantic white-sided dolphin White-beaked dolphin Peale's dolphin Hourglass dolphin Pacific white-sided dolphin Dusky dolphin Northern right whale dolphin Southern right whale dolphin Irrawaddy dolphin Australian snubfin dolphin Killer whale Melon-headed whale False killer whale Tucuxi dolphin (Gray river dolphin) Costero (Guiana river dolphin) Indo-Pacific humpbacked dolphin (Pacific humpback dolphin) Atlantic humpbacked dolphin Pan-tropical spotted dolphin Clymene dolphin Striped dolphin Atlantic spotted dolphin Spinner dolphin Rough-toothed dolphin Indian Ocean bottlenose dolphin Common bottlenose dolphin

Toothed whales (Odontoceti) (continued) Hyperoodontidae (Beaked whales) 52. Arnoux's beaked whale 53. Baird's beaked whale 54. Northern bottlenose whale 55.Southern bottlenose whale 56. Longman's beaked whale 57. Sowerby's beaked whale 58. Andrew's beaked whale 59. Hubbs' beaked whale 60. Blainville's beaked whale 61. Gervais' beaked whale 62. Ginkgo-toothed beaked whale 63. Gray's beaked whale 64. Hector's beaked whale 65. Layard's beaked whale (Strap-toothed whale) 66. True's beaked whale 67. Perrin's beaked whale 68. Peruvian beaked whale (Pygmy beaked whale) 69. Stejneger's beaked whale 70. Spade-toothed whale 71. Shepherd's Beaked Whale (Tasman beaked whale) 72. Cuvier's beaked whale Iniidae 73. Amazon river dolphin 74. Chinese river dolphin (Baiji) 75. Franciscana Kogiidae 76. Pygmy sperm whale 77. Dwarf sperm whale Monodontidae 78. Narwhal 79. Beluga Phocoenidae 80. Finless porpoise 81. Spectacled porpoise 82. Harbour porpoise (Common porpoise) 83. Gulf of California harbor porpoise (Vaquita) 84. Burmeister's porpoise 85. Dall's porpoise Physeteridae 86. Sperm whale Platanistidae 87. Ganges River dolphin 88. Indus River dolphin

Size comparison of all known extant cetacean species. Note the human diver at lower right for scale. Source: Chris Huh

References

• Dale W.Rice. 1998. Marine mammals of the world: systematics and distribution. Society of Marine Mammalogy Special Publication Number 4: 231 pp.
• “Committee on Taxonomy. 2009. List of marine mammal species and subspecies. Society for Marine Mammalogy, www.marinemammalscience.org, consulted on May 27, 2011.”

Further Reading

1. Smith, B.D., Zhou, K., Wang, D., Reeves, R.R., Barlow, J., Taylor, B.L. & Pitman, R. 2008. Lipotes vexillifer. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4.
2. Reilly, S.B., Bannister, J.L., Best, P.B., Brown, M., Brownell Jr., R.L., Butterworth, D.S., Clapham, P.J., Cooke, J., Donovan, G.P., Urbán, J. & Zerbini, A.N. 2008. Eubalaena glacialis. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4.
3. Rojas-Bracho, L., Reeves, R.R., Jaramillo-Legorreta, A. & Taylor, B.L. 2008. Phocoena sinus. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4.

Citation

Encyclopedia of Life, Peter Saundry & U.S. NOAA (2013). Cetaceans. ed. C. Michael Hogan. Encyclopedia of Earth. National Council for Science and Envrionment. Washington DC. Retrieved from http://editors.eol.org/e oearth/wiki/Cetaceans