? Irrawaddy Dolphin
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Cetacea Family: Delphinidae Genus: Orcaella Species: O. brevirostris
Binomial name
Orcaella brevirostris Gray, 1866
Irrawaddy Dolphin range

The Irrawaddy Dolphin (Orcaella brevirostris) is a species of dolphin found near coasts and in estuaries in parts of south-east Asia. Scientific classification or biological classification is how biologists group and categorize extinct and living species of organisms (as opposed to folk taxonomy). ... Phyla Subregnum Parazoa Porifera (sponges) Subregnum Agnotozoa Placozoa (trichoplax) Orthonectida (orthonectids) Rhombozoa (rhombozoans) Subregnum Eumetazoa Radiata (unranked) (radial symmetry) Ctenophora (comb jellies) Cnidaria (coral, jellyfish, anemones) Bilateria (unranked) (bilateral symmetry) Acoelomorpha (basal) Orthonectida (parasitic to flatworms, echinoderms, etc. ... Typical Classes Subphylum Urochordata - Tunicatas Ascidiacea Thaliacea Larvacea Subphylum Cephalochordata - Lancelets Subphylum Myxini - Hagfishes Subphylum Vertebrata - Vertebrates Petromyzontida - Lampreys Placodermi (extinct) Chondrichthyes - Cartilaginous fishes Acanthodii (extinct) Actinopterygii - Ray-finned fishes Actinistia - Coelacanths Dipnoi - Lungfishes Amphibia - Amphibians Reptilia - Reptiles Aves - Birds Mammalia - Mammals Chordates (phylum Chordata) include the vertebrates, together with... Orders Subclass Multituberculata (extinct) Plagiaulacida Cimolodonta Subclass Palaeoryctoides (extinct) Subclass Triconodonta (extinct) Subclass Eutheria (includes extinct ancestors)/Placentalia (excludes extinct ancestors) Afrosoricida Artiodactyla Carnivora Cetacea Chiroptera Cimolesta (extinct) Creodonta (extinct) Condylarthra (extinct) Dermoptera Desmostylia (extinct) Embrithopoda (extinct) Hyracoidea Insectivora Lagomorpha Litopterna (extinct) Macroscelidea Mesonychia (extinct) Notoungulata (extinct) Perissodactyla Pholidota Plesiadapiformes... Suborders Mysticeti Odontoceti (see text for families) The order Cetacea includes whales, dolphins and porpoises. ... Genera See text Oceanic dolphins are the members of the Delphinidae family of cetaceans. ... Species Irrawaddy Dolphin () Australian Snubfin Dolphin () The Snubfin Dolphins (Orcaella) are a genus of dolphins, long believed to be monotypic, the only species being the Irrawaddy Dolphin. ... In biology, binomial nomenclature is the formal method of naming species. ... John Edward Gray. ... , (C) User:Pcb21, 2004, User:Vardion 2003. ... Genera See article below. ... Asia is the largest and most populous region or continent depending on the definition. ...

Taxonomy

The Irrawaddy Dolphin was identified by Sir Richard Owen in 1866 and is one of two species in its genus (the other being the newly discovered Australian Snubfin Dolphin). It is similar to the beluga in appearance. It has sometimes been listed in either a family containing just itself and in Monodontidae and Delphinapteridae. Nowadays there is widespread agreement to list it in the Delphinidae family, a family of which the name was simply produced by merging the words Monodontidae and Delphinapteridae. Sir Richard Owen and Dinornis bird skeleton Sir Richard Owen (July 20, 1804 - December 18, 1892) was an English biologist, comparative anatomist and palaeontologist. ... Binomial name Orcaella heinsohni Beasley, Robertson, Arnold, 2005 The Australian Snubfin Dolphin (Orcaella heinsohni) is a recently recognised species of dolphin first described in 2005. ... Binomial name Delphinapterus leucas (Pallas, 1776) Beluga range The Beluga Whale or White Whale (Delphinapterus leucas) is an Arctic and sub-arctic species of cetacean. ... Genera Delphinapterus Monodon The cetacean family Monodontidae comprises two unusual whale species, the Narwhal, in which the male has a long tusk, and the white Beluga. ... Genera See text Oceanic dolphins are the members of the Delphinidae family of cetaceans. ...

Genetically the Irrawaddy Dolphin is closely related to the Orca. The species name brevirostris comes from the Latin meaning short-beaked. In 2005 genetic analysis showed that the Australian Snubfin Dolphin found at the coast of northern Australia forms a second species in the Orcaella genus. Binomial name Orcinus orca Linnaeus, 1758 Orca range (in blue) The orca (Orcinus orca) is the largest member of the oceanic dolphin family. ... Latin is an ancient Indo-European language originally spoken in the region around Rome called Latium. ... Binomial name Orcaella heinsohni Beasley, Robertson, Arnold, 2005 The Australian Snubfin Dolphin (Orcaella heinsohni) is a recently recognised species of dolphin first described in 2005. ...

Physical description

This species has a large melon and a blunt, rounded head. Its beak is indistinct. The dorsal fin is short, blunt and triangular. It is located about two-thirds of the way along the back. The flippers are long and broad. It is lightly coloured all over - slightly more white on the underside than the back. It appears whiter than it actually is when set against the background of a muddy river. The melon is a oily, fatty lump of tissue found at the centre of the forehead of most dolphins and toothed whales. ... Dorsal Fin of the Orca A dorsal fin is a fin located on the backs of fishes, whales, dolphins and porpoises. ...

Length is about 1 m at birth and 2.3 m at full maturity. Birth weight is about 10 kg. Adult weight exceeds 130 kg. Lifespan is about 30 years.

The Irrawaddy Dolphin is a slow swimmer. It surfaces in a rolling fashion and lifts its tail fluke clear of the water for a deep dive only. Irrawaddy Dolphins spit streams of water from their mouths while spyhopping. Dolphins of the species kept in captivity have been trained to do this on demand.

Population and distribution

Although sometimes called the Irrawaddy River Dolphin, it is not a true river dolphin but an oceanic dolphin that lives near coasts and enters rivers, including the Ganges and the Mekong as well as the Ayeyarwady River (Irrawaddy River) from which it takes its name. Its range extends from the Bay of Bengal to New Guinea and northern Australia. Families See text River dolphins are four species of dolphin which reside in freshwater rivers and estuarys. ... Genera See text Oceanic dolphins are the members of the Delphinidae family of cetaceans. ... Early morning on the Ganges The River Ganges (Ganga in Indian languages) (Devanagiri गंगा) is a major river in northern India. ... View of the Mekong before the sunset The Mekong is one of the worlds major rivers. ... The Ayeyarwady River (Burmese: ; formerly known as the Irrawaddy River) flows through the centre of Myanmar (formerly Burma). ... A map showing the location of the Bay of Bengal. ...

Human interaction

On account of their coastal nature Irrawaddy Dolphins are more susceptible to interference than other river dolphins. The most direct threat is the capturing of Irrawaddys for their oil. As an endangered species, they are legally protected from hunting, however, enforcement may be poor along tens of thousands of miles of coast line. Entanglements in gillnets and deaths injury due to explosives used in fishing are common in Vietnam and Thailand. All along its distribution population and other habitat degradation worries conservationists. Human influence such as nets crossing river channels restrict movement and isolate populations, causing them to decline. The population in India's Chilka Lake, which has suffered from entanglement in fisher's gill nets and drag nets, is believed to have dwindled to as few as 50 individuals. The endangered Sea Otter An endangered species is a population of organisms (frequently but not always a taxonomic species) which is either (a) so few in number or (b) threatened by changing environmental or predation parameters that it is at risk of becoming extinct. ... A gillnet is a type of fishing net, a type of which is the driftnet (which is a drifting gillnet - i. ... Chilka Lake (also Chilika Lake) is a brackish water coastal lake in Indias Orissa state, south of the mouth of the Mahanadi River. ...

Irrawaddys are also taken to perform in aquariums. Though this practice is less common than it used to be, it still has a significant local impact. For other uses, see Aquarium (disambiguation). ...

The IUCN lists several populations, including those in the Mahakam River and Malampaya Sound, as critically endangered. The World Conservation Union or International Union for Conservation of Nature and Natural Resources (IUCN) is an international organization dedicated to natural resource conservation. ... The Mahakam River flows 980 km from the highlands of Borneo, district Long Apari to its mouth in Makassar Strait. ...

References

• National Audobon Society Guide to Marine Mammals of the World ISBN 0375411410
• Encyclopedia of Marine Mammals ISBN 0125513402
• Whales, Dolphins and Porpoises, Mark Carwardine, ISBN 0751327816
• IUCN Red list entry for Irrawaddy Dolphins

External Links

• WWF Irrawaddy page
• ARKive - images and movies of the Irrawaddy dolphin (Orcaella brevirostris)
• National geographic Gold mining, nets endanger dolphin (contains photo)