Oceanic dolphin

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iOceanic dolphins
Pacific White-sided Dolphins
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Cetacea Suborder: Odontoceti Family: Delphinidae Gray, 1821
Genera
See text.

Oceanic dolphins are the members of the Delphinidae family of cetaceans. These aquatic mammals are related to whales and porpoises.

As the name implies, these dolphins tend to be found in the open seas, unlike the river dolphins, although a few species such as the Irrawaddy Dolphin are coastal or riverine.

Six of the larger species in the Delphinidae, the Orca and the Pilot, Melon-headed, Pygmy Killer and False Killer Whales, are commonly called whales, rather than dolphins. They are also sometimes collectively known as "blackfish".

The Delphinidae vary in size from 1.2 metres and 40 kg (Heaviside's Dolphin), up to 7 meters and 4.5 tonnes (the Orca). Most species weigh between about 50 and about 200 kg. They are found worldwide, mostly in the shallower seas of the continental shelves, and all are carnivores, mostly taking fish and squid.

[edit] Taxonomy

ORDER CETACEA

• SUBORDER MYSTICETI
• SUBORDER ODONTOCETI
  • Superfamily Platanistoidea: All river dolphins
    • Family Platanistidae: Indus and Ganges river dolphins
    • Family Lipotidae: Baiji (Yangtze River Dolphin)
    • Family Iniidae: Boto (Amazon River Dolphin)
    • Family Pontoporiidae: Franciscana (La Plata Dolphin)
  • Family Delphinidae
    • Genus Peponocephala
      • Melon-headed Whale, Peponocephala electra
    • Genus Orcinus
      • Orca (Killer Whale), Orcinus orca
    • Genus Feresa
      • Pygmy Killer Whale, Feresa attenuata
    • Genus Pseudorca
      • False Killer Whale, Pseudorca crassidens
    • Genus Globicephala
      • Long-finned Pilot Whale, Globicephala melas
      • Short-finned Pilot Whale, Globicephala macrorhynchus
    • Genus Delphinus
      • Long-beaked Common Dolphin, Delphinus capensis
      • Short-beaked Common Dolphin, Delphinus delphis
    • Genus Lissodelphis
      • Northern Rightwhale Dolphin, Lissodelphis borealis
      • Southern Rightwhale Dolphin, Lissodelphis peronii
    • Genus Sotalia
      • Tucuxi, Sotalia fluviatilis
    • Genus Sousa
      • Pacific Humpback Dolphin, Sousa chinensis
      • Indian Humpback Dolphin, Sousa plumbea
      • Atlantic Humpback Dolphin, Sousa teuszii
    • Genus Stenella
      • Atlantic Spotted Dolphin, Stenella frontalis
      • Clymene Dolphin, Stenella clymene
      • Pantropical Spotted Dolphin, Stenella attenuata
      • Spinner Dolphin, Stenella longirostris
      • Striped Dolphin, Stenella coeruleoalba
    • Genus Steno
      • Rough-toothed Dolphin, Steno bredanensis
    • Genus Tursiops
      • Common Bottlenose Dolphin, Tursiops truncatus
      • Indo-Pacific Bottlenose Dolphin, Tursiops aduncus
    • Genus Cephalorhynchus
      • Chilean Dolphin, Cephalorhynchus eutropia
      • Commerson's Dolphin, Cephalorhynchus commersonii
      • Heaviside's Dolphin, Cephalorhynchus heavisidii
      • Hector's Dolphin, Cephalorhynchus hectori
    • Genus Grampus
      • Risso's Dolphin, Grampus griseus
    • Genus Lagenodelphis
      • Fraser's Dolphin, Lagenodelphis hosei
    • Genus Lagenorhynchus
      • Atlantic White-sided Dolphin, Lagenorhynchus acutus
      • Dusky Dolphin, Lagenorhynchus obscurus
      • Hourglass Dolphin, Lagenorhynchus cruciger
      • Pacific White-sided Dolphin, Lagenorhynchus obliquidens
      • Peale's Dolphin, Lagenorhynchus australis
      • White-beaked Dolphin, Lagenorhynchus albirostris
    • Genus Orcaella
      • Irrawaddy Dolphin, Orcaella brevirostris
      • Australian Snubfin Dolphin, Orcaella heinsohni
  • Family Phocoenidae: porpoises
  • Family Monodontidae: Beluga and Narwhal
  • Family Physeteridae: Sperm Whale
  • Family Kogiidae: Pygmy Sperm Whale and Dwarf Sperm Whale
  • Family Ziphiidae: beaked whales

Recent molecular analyses indicate that several delphinid genera (especially Stenella and Lagenorhynchus) are not monophyletic as currently recognized. Thus, the coming years will likely see significant taxonomic revisions within the family.

[edit] References

• LeDuc, R.G., Perrin, W.F., Dizon, A.E. (1999). Phylogenetic relationships among the delphinid cetaceans based on full cytochrome b sequences. Marine Mammal Science 15, 619–648.
• May-Collado, L., Agnarsson, I. (2006). Cytochrome b and Bayesian inference of whale phylogeny. Molecular Phylogenetics and Evolution 38, 344-354.