Cumacean general biology

[Cumacean Biology]

[cumacean drawing 1] Anatomy

The carapace of cumaceans is swollen and covers the head and some of the thorax. Often it is complexly sculptured but in other species it is smooth. The legs of the thorax are short and several help in feeding. Between a pair of lobes of the carapace are several minute eyes. The abdomen is a cylindrical sequence of segments ending in a fork-like tail. Many species are small, rarely more than about 8 mm long, but some species grow to 25 mm.

Ecology

Cumaceans burrow into the surface of sandy and muddy sediments but can also be found in the sediment trapped among macroalgae. At night especially cumaceans can be active swimmers in the open water and this is probably where mating occurs. Food is obtained by filtering water just above the sediment and grazing on the surface of sand grains. Cumaceans can be dug out of sandy sediment but the most effective way of catching them is by attracting them to lights at night.

Reproduction

The sexes are separate and often very different from each other. Males may have short limbs on the abdominal segments while females may not, and males may have very long antennae. Females carry the eggs in a marsupium made from branches of the thoracic legs, making the front of the animal more swollen than normal. The eggs hatch as miniature adults.

Distribution

Cumaceans are almost exclusively marine but estuarine species occur. Hundreds of species live in shallow water in southern Australia and there are many more in all other oceans.

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Feedback and queries should be sent to the Discovery Centre at Museum Victoria.
Please note, the Discovery Centre can help you only with questions about crustaceans from southeastern Australia. It can not advise on the care of pet hermit crabs or on crustaceans from other regions.