Spelaeogriphacea

(Spelaeogriphaceans)

Phylum Arthropoda Subphylum Crustacea Class Malacostraca Order Spelaeogriphacea Number of families 1

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Small, cave-dwelling, freshwater crustaceans having a short carapace, eye lobes without eyes, and appendages on all abdominal somites

Illustration: Spelaeogriphus lepidops. (Illustration by Dan Erickson)

Evolution and systematics

Spelaeogriphaceans are known from one fossil species, found in New Brunswick, Canada, and three recent species. The first living species was found in a stream at the bottom of Bat Cave in Table Mountain outside Cape Town, South Africa. The two additional species are known from caves in Brazil and Western Australia. Spelaeogriphaceans are members of the short, branchial carapace clade within the superorder Peracarida. There is only one family, Spelaeogriphidae.

Physical characteristics

Spelaeogriphaceans have elongate, cylindrical bodies. A short carapace extends posteriorly from the back of the head. Both pairs of antennae are elongate and biramous. On the head are eye lobes, but no trace of the eye can be found. The first thoracic somite is fused to the head and its appendage is a maxilliped, which has a branchial epipod that extends into the branchial chamber formed by the short carapace. The mouthparts, including the maxilliped, are armed with long, stiff setae, suggesting they are used in a sweeping motion during feeding. The remaining thoracopods, known as pere-opods, have endopods developed for walking, and exopods used to circulate water past the body. It is possible that the anterior exopods are also used for respiratory gas exchange. In females, the first five pereopods bear small brood plates. The appendages of the abdominal somites, known as pleopods, are moderately strongly developed, except for the last pair. At the end of the abdomen is a large fleshy telson and a pair of flattened uropods.

Distribution

Spelaeogriphaceans are known only from caves in South Africa, Brazil, and Western Australia.

Habitat

They are found in freshwater streams or pools in caves.

Behavior

Little is known about the behavior of these animals. They are unable to burrow into the sand or to swim. They walk about on the surface of the sand in the cave streams or pools and are easily swept about if the current is moderately strong.

Feeding ecology and diet

Spelaeogriphaceans appear to feed on plant detritus washed into the caves. They sweep their mouth appendages over the substrate in order to pick up small particles.

Reproductive biology

Nothing is known about mating or development. Females carry 10-12 eggs in the brood pouch.

Conservation status

Although no species are listed by the IUCN, the South African species, Spelaeogriphus lepidops, is protected locally and can be collected only by permit. Numbers seem to be stable.

Significance to humans

The species in this order are important as relicts of past life.

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