Spelaeogriphaceans: Spelaeogriphacea

views updated

SPELAEOGRIPHACEANS: Spelaeogriphacea

NO COMMON NAME (Spelaeogriphus lepidops): SPECIES ACCOUNT

PHYSICAL CHARACTERISTICS

Spelaeogriphaceans (speh-lee-oh-grih-FAY-see-ans) are blind with long, cylinder-shaped bodies. Adults measure from 0.12 to 0.28 inches (3.1 to 7.2 millimeters) and have three distinct body regions: head, thorax, and abdomen. The head has a distinct, beaklike projection called the rostrum. Both pairs of antennae are long and branched, or biramous (BY-ray-mus). The eyestalks are present, but the eyes are not. The jaws, or mandibles, are uniramous (YU-neh-RAY-mus) or unbranched. A short, shieldlike carapace covers the back of the head and the first two segments of the segmented thorax. The first thoracic segment is firmly attached, or fused, to both the head and the carapace. There is one pair of maxillipeds, thoracic limbs that work together with the mouthparts.

The remaining pairs of thoracic limbs are called pereopods (PAIR-ee-oh-pawds). The pereopods are used for walking and are also used to move oxygen-carrying water past the body. The abdomen has six segments. Each of the first five segments of the abdomen has a pair of biramous limbs called pleopods (PLEE-oh-pawds). The first four pairs of pleopods are well developed and paddlelike; the fifth pair is very small. At the end of the abdomen is a pair of slender biramous appendages called the uropods (YUR-oh-pawds). In between the uropods is a slender, taillike segment called the telson. The telson is not tightly joined with, or fused to, the last abdominal segment. The telson and uropods do not join together to form a fanlike tail.

GEOGRAPHIC RANGE

Spelaeogriphaceans are known only from small regions of South Africa, Brazil, and Western Australia.

HABITAT

They are found in freshwater streams or pools in caves or in underground springs.

DIET

Spelaeogriphaceans are thought to feed on bits of plants that are washed into the caves and underground springs. They use their mouthparts to sweep up small particles off rocks.

BEHAVIOR AND REPRODUCTION

Very little is known about these animals. They do not burrow or swim. Instead, they walk around on the bottom of freshwater habitats in caves or underground springs. Males and females are known, but mating has never been observed. The females carry ten to twelve eggs in the brood pouch located under the thorax and surrounded by the carapace.

SPELAEOGRIPHACEANS AND PEOPLE

Spelaeogriphaceans are of special interest to scientists studying the lives and evolution of crustaceans. Evolution is how organisms slowly change and adjust to their environments over millions of years.

THE SPINELESS WONDERS OF TABLE MOUNTAIN

Table Mountain, located near Cape Town, South Africa, is home to many plants and animals that are found nowhere else in the world. They are called endemics (ihn-DEH-mihks). Endemic organisms are found only in one place or habitat. There are 112 species of animals endemic to Table Mountain; 111 of these are invertebrates (in-VER-teh-brehts), or animals without backbones. They include the first spelaeogriphacean ever discovered, Spelaeogriphus lepidops.

CONSERVATION STATUS

No species of spelaeogriphaceans are considered endangered or threatened. The South African Spelaeogriphus lepidops, known from a single cave, is protected locally.

NO COMMON NAME (Spelaeogriphus lepidops): SPECIES ACCOUNT

Physical characteristics: This species is white, or transparent, with food clearly visible in the gut. Adults range in length from 0.22 to 0.28 inches (5.6 to 7.2 millimeters).

Geographic range: Spelaeogriphus lepidops lives only in one stream and pool in the Bat Cave system in Table Mountain, near Cape Town, South Africa.

Habitat: Spelaeogriphus lepidops lives in a freshwater stream and pool in a cave.

Diet: This species probably eats bits of plants that wash down into the cave from bogs on top of Table Mountain.

Behavior and reproduction: Spelaeogriphus lepidops use their mouthparts like brushes to sweep up bits of plant materials into their mouths. Males and females are known, but mating has never been observed. Observations of animals in captivity suggest that they hatch with the full number of thoracic segments.

Spelaeogriphus lepidops and people: This is one of many unique kinds of animals that are found only on Table Mountain.

Conservation status: The Bat Cave system and its unique animals are all protected. Special collecting permits are required even for scientists. ∎

FOR MORE INFORMATION

Books:

Schram, F. R. Crustacea. Oxford, U.K.: Oxford University Press, 1986.

Periodicals:

Gordon, I. "On Spelaeogriphus, a New Cavernicolous Crustacean from South Africa." Zoology 5 (1957): 31-47.

Poore, G. B., and W. F. Humphreys. "First Record of Spelaeogriphacea (Crustacea) from Australia; A New Genus and Species from an Aquifer in the Arid Pilbara of Western Australia." Crustaceana 71 (1998): 721-742.