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Oncaea media

Giesbrecht (1891)

Download a fact sheet for Oncaea media (PDF 330KB)


Phylum Arthropoda
Subphylum Crustacea
Class Maxillopoda
Subclass Copepoda
Order Poecilostomatoida
Family Oncaeidae
Genus Oncaea
Species media


  • Female: 0.65 – 0.96 mm
  • Male: 0.56 – 0.67 mm

Distinguishing characteristics

  • Size
  • Form and location of genital apertures and sclerotization


  • Prosome 2.2 times the length of urosome, excluding caudal rami, 1.9 times urosome length, including caudal rami
  • Caudal rami about as long as wide, much shorter than female


  • Exoskeleton moderately chitinised
  • Prosome 2.6 times length of urosome, excluding caudal rami, 2.2 times urosome length including caudal rami
  • P2 bearing somite without projection
  • Genital double somite 1.9 times as long as maximum width (in dorsal aspect) and 2.6 times as long as post genital somites combined
  • Double-curved sclerotization between genital apertures
  • Anal somite 2 times wider than long, about 2/3 length of caudal rami


Closely related to O.scottodicarloi, to separate look at:

  • Proportional lengths of urosome somites; elongated genital somite in, genital somite is 2 times as long as the rest of urosome
  • Form and location of sclerotization between genital apertures; in genital openings are closer to top 1/3 of genital somite, in O.scottodicarloi genital openings are almost ½ way from top genital somite
  • Relative lengths of endopod spines of P4


  • Epipelagic-mesopelagic
  • Inshore, coastal and oceanic
  • Australian distribution includes Gulf of Carpentaria, Great Barrier Reef, the North West Cape, New South Wales and south east including Tasmania
  • World distribution: widespread in tropical and sub tropical waters of the Pacific, Indian and Atlantic Oceans


  • Eggs carried in paired sacs
  • Omnivorous
  • Feeds on small zooplankton and appendicularian houses, that form marine snow containing phytoplankton and bacteria


  • Heron, G. A. and J. M. Bradford-Grieve (1995). "The marine faunaof New Zealand: Pelagic Copepoda: Poecilostomatoida: Oncaeidae." New Zealand Oceanographic Institute Memoir 104.
  • Ohtsuka et al (1996)
  • Razouls C., de Bovée F., Kouwenberg J. et Desreumaux N., 2005-2009. Diversity and Geographic Distribution of Marine Planktonic Copepods. Available at
  • Taw (1978)