Marine research on cumaceans from around the world.

Ecology of the Cumacea

The ecology of cumaceans is as understudied as all other aspects of their biology, and cumaceans have been generally assumed to be deposit feeders that burrow shallowly into the sediment. This lifestyle has been supported for some species (e. g. Blazewicz-Paskowycz & Ligowski 2002), but the presence of polychaete jaws in the guts of Nannastacidae (Cartes & Sorbe 1996) suggests strongly that cumaceans can be micropredators, the piercing mandible morphology of the Nannastacidae has long been suggested to indicate predation on Foraminifera (Jones 1976, Cartes & Sorbe 1996), two species of the Gynodiastylidae are known to build tubes (Harada 1962, Gerken 2001), and many species of the Gynodiastylidae and some species of the Vaunthomsoniinae have legs that are probably used for filter feeding (Hale 1943, Gerken 2001). Clearly, there is a diversity of occupations in the Cumacea, with more still to be discovered.

Cumaceans are regularly found in bird and fish stomach contents, comprising as much as 100% of the contents of flatfish guts, indicating that when abundant, cumaceans can be significant prey items for macrofauna. While this has not been explored, cumaceans may provide a means of remobilizing carbon from the sediments back into the water column, through predation by mobile predators such as fish and birds.

Cumaceans can migrate into the plankton in shallow water habitats for short periods of time, but there is not much possibility of dispersal by water currents. When sufficient records exist to determine a range, the ranges tend to be relatively small, incorporating 1-2 biogeographic provinces (such as those defined by Briggs), and species are rarely found throughout an entire ocean basin or a hemisphere. It is probable that the few species which are reported as having large distributions are, instead, complexes of similar species. In general, cumacean distributions appear to be limited by a combination of a requirement for specific sediment grain sizes and organic characteristics, depth, and temperature. Juvenile dispersal is limited because there is no planktonic stage, the young are brooded in a ventral pouch. When released from the pouch, the young resemble the adults. Adults are limited in dispersal capabilities by little to no capacity for swimming, due to reduced or lost swimming appendages (exopods and pleopods). The only long distance dispersal mechanism identified in the Cumacea is human mediated dispersal, presumably via ballast water, which resulted in the introduction of Nippoleucon hinumensis across the Pacific from Japan to the Oregon coast. As N. hinumensis is now among the top 10 most abundant invertebrates in Yaquina Bay, Oregon, it is obvious that cumaceans can be quite competitive when introduced to new habitats.

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