Key to Australian Freshwater and Terrestrial Invertebrates

Phylum Arthropoda
Subphylum Crustacea
Class Remipedia
Order Nectiopoda

Common name: remipedes

Overview

Remipedes are troglobitic, inhabiting cave and groundwater systems underneath the ground. They are free-swimming and characterised by their short head and elongate trunk with paddle-like swimming appendages present on each segment. The class was not discovered until 1981, and the fauna of Australia and the world in general is very poorly known. Like many subterranean animals they characteristically have little or no pigment and are eyeless. Remipedes superficially resemble the Myriapoda (centipedes and millipedes) but share many more characters with the Crustacea, although their position inside this group is unresolved.

Distribution and diversity

There are only 20 species of remipedes described from three families worldwide. All living remipedes are in the order Nectiopoda. A second order, Enantiopoda, includes the two described fossil species. All extant species have been found in anchialine cave systems in the Caribbean, Canary Islands and Australia. Australia�s fauna consists of only one described species, Lasionectes exleyi, from a cave on the Cape Range peninsula, Western Australia. It is likely that the global diversity of the class is much higher than currently known due to the difficulty in finding and collecting animals which live within anchialine caves.

Life cycle

Remipedes are hermaphrodites. The seventh trunk segment bears female gonopores whilst the male pores are located on the 14th segment. There is little known about the life cycle of Remipedia, although it is known that free-swimming larvae develop gradually into adults.

Feeding

Whilst it is presumed that remipedes are carnivorous because of the presence of powerful prehensile limbs on the head region and reports from cave divers who noted remipedes hunting shrimps, observations of live remipedes in a laboratory found that they spent the majority of the time filter-feeding, ignoring any larger live food provided.

Ecology

All known remipede species are from submerged cave systems that connect the marine environment to a groundwater source. L. exleyi was collected between 20-30m depth within a cave, in association with other crustaceans such as ostracods and decapods, and a species of fish.