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Neocalanus tonsus

Brady (1883)

Download a fact sheet Neocalanus tonsus (PDF 489KB)


Phylum Arthropoda
Subphylum Crustacea
Class Maxillopoda
Subclass Copepoda
Order Calanoida
Family Calanidae
Genus Neocalanus
Species tonsus


  • Female: 3.3 - 4.1 mm
  • Male: 3.4 - 4.4 mm

Distinguishing characteristics

  • P2 in both sexes with a recurved spine at the outer distal border or exopodite segment 1
  • Coxa of P5 inner border without serrations in both sexes
  • Basis of P2 to P5 with conspicuous posterior surface spines on inner distal border of segment


  • Cephalosome and pedigerous somite 1 separate
  • 5th leg only slightly asymmetrical, exopods without inner edge setae


  • Cephalosome and pedigerous somite 1 separate but not as distinctly as joints between other pedigerous segments
  • Basis of P1 without large spine at base of inner setae unlike N. gracilis
  • P1 to 5 all similar
  • Genital segment bulbous at mid length in dorsal view


  • Subantarctic and Antarctic (but not coastal Antarctic)
  • Indian, Pacific and Atlantic
  • Occasionally taken north of Sub Tropical Convergence in deep water


  • Reproduction might occur at mesopelagic depths
  • Fine particle feeder, probably omnivorous
  • Ingests up to 3.8% of body carbon and 5.7% of nitrogen per day
  • Can form surface aggregations up to several 100 metres in length
  • Undertakes ontogenetic vertical migrations
  • Eggs released into water column; produces up to 450 eggs per female
  • Two egg production strategies: Mesopelagic-dwelling females use stored lipids for egg production in winter, and epipelagic dwelling females rely on ambient food supply for egg production in spring


  • Bradford-Grieve, J. M. (1994). The marine fauna of New Zealand: Pelagic Copepoda: Megacalanidae, Calanidae, Paracalanidae, Mecynoceridae, Eucalanidae, Spinocalanidae, Clausocalanidae. National Institute of Water and Atmospheric Research, Wellington, New Zealand.
  • Boxshall, G. A. and S. H. Halsey (2004). "An introduction to copepod diversity." Ray Society Publications 166: i-xv, 1-966.
  • Bradford-Grieve, J. M., E. L. Markhaseva, et al. (1999). Copepoda. South Atlantic Zooplankton. D. Boltovskoy. Leiden, The Netherlands, Backhuys Publishers. 1: 869-1098.
  • Brodsky K.A., 1967. Calanoida of the Far Eastern seas and polar basin of the URSS. (Translation of Brodskii K.A., 1950, by Israel Program scient. Trans.), 1-440.
  • Jillett J.B., 1968. Calanus tonsus (Copepoda, Calanoida) in southern New Zealand waters with notes on the male. Austr. J. mar. freshwat. Res., 19 (1): 19-30.Kawamura (1974)
  • Ohman (1987)
  • Razouls C., de Bovée F., Kouwenberg J. et Desreumaux N., 2005-2009. Diversity and Geographic Distribution of Marine Planktonic Copepods. Available at
  • Taw, N. (1978). Some common components of the zooplankton of the southeastern coastal waters of Tasmania. Papers and Proceedings of the Royal Society of Tasmania 112: 69-136.