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Clausocalanus arcuicornis

Dana (1849)

Download a fact sheet for Clausocalanus arcuicornis (PDF 342KB)


Phylum Arthropoda
Subphylum Crustacea
Class Maxillopoda
Subclass Copepoda
Order Calanoida
Family Clausocalanidae
Genus Clausocalanus
Species arcuicornis


  • Female: 1.15 - 1.62 mm
  • Male: 0.97 - 1.17 mm

Distinguishing characteristics

  • Form of seminal receptacle
  • Profile of genital somite straight in lateral view
  • Prosome : Urosome ratio
  • Shape of forehead and rostrum


  • Rostrum in lateral view knoblike and protruding ventrally
  • Pereiopod 5 right, short, 3 segmented
  • Pereiopod 5 left leg is longer than urosome, robust, with long, slender, straight setae distally
  • Prosome urosome ratio 1.9¡ª2.51:1
  • 2nd urosome somite as long as the following 2 somites together


  • Antennule as long or slightly longer than prosome
  • Rostrum in lateral view is short, bifurcated, thick at base, usually straight or slightly curved and directed ventrally
  • The 3rd segment of P5 as long as the preceding 2 segments together; segment 3 bifurcated, sometimes with tiny spinlues on inner and outer margins
  • Prosome : Urosome ratio 2.65-3.22:1
  • Urosome shorter than 4th legs
  • Genital somite in lateral view straight, or slightly concave, in region of seminal receptacle
  • Genital somite 1.5 times as long as urosome somite 3
  • Caudal rami about as long as broad


  • Epipelagic
  • Inshore coastal, coastal and oceanic
  • Australian distribution includes Tasmania, North West Cape, New South Wales and Great Barrier Reef
  • World distribution: widespread in tropical and subtropical waters of the Pacific, Indian and Atlantic Oceans


  • Tropical-subtropical, circumglobal
  • Can be transported into temperate regions with warm currents
  • Most abundant off New South Wales during April and May; 17 ¨C 19º sea surface temperatures
  • Carries eggs in a single, fragile sac
  • Herbivorous


  • Bradford-Grieve, J. M., E. L. Markhaseva, et al. (1999). Copepoda. South Atlantic Zooplankton. D. Boltovskoy. Leiden, The Netherlands, Backhuys Publishers. 1: 869-1098.
  • Conway, D. V. P., White, R.G., Hugues-Dit-Ciles, J., Gallienne, C.P. and Robins, D.B. (2003). Guide to the coastal and surface zooplankton of the south-western Indian Ocean, Marine Biological Association of the United Kingdom
  • Dakin, W. J. and Colefax A., (1940). "The plankton of the Australian coastal waters off New South Wales Part I." Publications of the University of Sydney: 210.
  • Frost B, Fleminger A (1968). A revision of the genus Clausocalanus (Copepoda: Calanoida) with remarks on distributional patterns in diagnostic characters. Bulletin of Scripps Institution of Oceanography 12:1-235
  • Razouls C., de Bovée F., Kouwenberg J. et Desreumaux N., 2005-2009. Diversity and Geographic Distribution of Marine Planktonic Copepods. Available at
  • Saiz & Calbert (1999)