Image Key > Copepoda > Calanoida > Calanidae > Calanus australis

• Male: 2.5-3.3 mm.
• Female: 2.7-3.2 mm.

• Relatively large species.
• Cephalosome is rounded anteriorly.
• Inner margin of basipodite (2nd segment) 1 of leg 5 is serrated (toothed).
• No recurved spine on the outer distal border of the 1st exopodite segment of leg 2.
• 1st antenna exceeds the body length by a few segments (Nyan Taw 1978, Bradford-Grieve 1999).
  

• 5th pereiopods are of unequal length.
• Endopodite of left leg 5 extends only slightly beyond exopodite segment 1 of the same leg.
• Right exopodite of leg 5 extends more than half way along left exopodite segment 2.

• 1st antenna just reaches the tip of the caudal rami.
• Edge of basipodite 1 of leg 5 is convex and serrated with 15–22 triangular teeth.
• Terminal spine of exopod segment 3 of leg 5 is shorter than its segment.

• Epipelagic (occurs in upper 200 m).
• Inshore, coastal and oceanic waters of south-eastern Australia and New Zealand.
• New Zealand and Sub-antarctic waters (Farran 1929), south-eastern Australian waters (Dalkin and Colefax 1933, 1940), south of Tasmania (Vervoort 1957), Derwent River mouth, D’Entrecasteaux Channel (Ong 1967) as Calanus helgolandicus, south-east Tasmania (Nyan Taw 1978).

• Often dominates copepod biomass in near-shore temperate waters, as well as being abundant numerically.
• Can reach high abundances in south-eastern Australian coastal and oceanic waters.
• Maximum abundance during summer, with stage C5 outnumbering adults (Nyan Taw and Ritz 1979).
• Appears to prefer seasonally stratified coastal waters and decreases rapidly in abundance as stratification weakens in offshore waters (Sabatini et al. 2000).
• Summer breeding generally coincides with phytoplankton bloom.
• Stage C5 often carry large lipid stores and might enter diapause in the early autumn.
• Despite its implied importance little is known about population biology beyond general distribution (Sabatini et al. 2000).