[4][7] In the Antarctic autumn, adult C. rastrospinosus migrate to shallow waters to spawn at a depth of 200–300 m. The eggs are scattered and hatch six months later around April.

[9][10] In 2011 Tokyo Sea Life Park claimed that C. rastrospinosus has totally transparent blood "like clear water", after dissecting a specimen.

It is believed they benefit from loss of reliance on haemoglobin-containing erythrocytes for oxygen transport by having less viscous, more easily pumped blood.

[12] They compensate for this loss by having lower metabolic rates, larger gills, scaleless skin that can contribute more to gas exchange, wider capillaries and significantly increased blood volume and cardiac output.

A male and female pair were donated along with other species by fishermen of the Fukuei-maru krill trawler as part of a programme to collect bycatch for the park.