Rhincalanus nasutus

Taxon-Order: 
Calanoida

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Distribution: 
California Current System; see Goetze and Ohman (2010)
Habitat: 
Surface to below 2000 m.
Size: 
Female 3.6-5.1 mm; male 2.7-3.8 mm
Diet: 
Phytoplankton and microzooplankton.
Useful Facts or Characters: 

Body is transparent with slight reddish or yellowish color in life.  1st antennae longer than body, and often outstretched.  In both sexes the head is triangular and acute.  The female genital segment has 2 spines on the dorsal surface.

Natural History: 

Previously considered cosmpolitan, but now recognized as a complex of at least 8 genetic lineages (Goetze and Ohman 2010).  Each has a different geographic distribution, one of which is in the California Current System.

References: 

http://www.marinespecies.org/copepoda/aphia.php?p=taxdetails&id=104543

http://copepodes.obs-banyuls.fr/en/fichesp.php?sp=707

Goetze, E. (2003) Cryptic speciation on the high seas; global phylogenetics of the copepod family Eucalanidae. Proceedings of the Royal Society of London 270: 2321-2331.

Goetze, E., and Ohman, M. D. (2010) Integrated molecular and morphological biogeography of the calanoid copepod family Eucalanidae. Deep-Sea Research Part II-Topical Studies in Oceanography 57: 2110-2129.

Ohman, M.D., Drits, A.V., Clarke, M.E., and Plourde, S. (1998) Differential dormancy of co-occurring copepods. Deep-Sea Research II 45: 1709-1740.