Phylum Arthropoda
Subphylum Crustacea
Class Remipedia
Order Nectiopoda
Family Speleonectidae

Speleonectes lucayensis Yager, 1981


Taxonomic Characterization: Remipedes are free swimming, troglobitic crustaceans characterized by a short head followed by an elongate trunk. The head is covered by a cephalic shield. All species have a pair of slender, cylindrical pre-antennal frontal processes. The trunk lacks tagmosis and is composed of numerous segments each bearing a pair of biramous, paddlelike swimming appendages.
Remipedes lack eyes and body pigmentation. Their appendages have a vast array of very diverse setae and sensilla which enable them to sense an environment devoid of light (Yager, 1994).
Speleonectes lucayensis is characterized by body elongate, slender, subcylindrical; without pigment or eyes. Cephalic shield present. Cephalon bearing pair of preantennular frontal processes. First antenna biramous. Maxila 1 and 2 and maxilliped well developed, prehensile. Maxilliped segment fused to cephalon. Natatory: trunk with numerous, similar segments, essentially all with homonymous, laterally directed, biramus swimming appendages.

Ecological Classification: Stygobitic

Size: Adult's total length ranges from 22-24 mm.

Number of Species in Genus: Nine, all stygobitic

Genus Range:

Species Range: Known from Lucayan Caverns, Grand Bahama Island as well as anchialine caves on Abaco, Andros and Cat Islands, Bahamas (Yager, 1994)

Closest Related Species: S. benjamini Yager, 1987

Habitat: Anchialine limestone caves

Ecology: Specimens were collected in fully marine salinity (35 ppt) below a density interface in waters depleted in dissolved oxygen (typically less than 1 mg/l). Remipedes are predatory. They are characteristically found swimming within the cave water column.

Life History: According to Yager (1994):
"Remipedes are simultaneous hermaphrodites. The ovary originates in the posterior portion of the head and lies dorsal to the midgut. The oviducts extend ventrally to the 7th swimming or trunk appendages where the female gonopores are located. The female gonopore is a semicircular structure on the posterior base of the protopod.
The testes are paired organs which originate in the 7th trunk segment and extend posteriorly until about the 10th trunk segment. At this position there is a transition from testes to vas deferens. The vas deferens extends to the male gonopores located at the base of the 14th swimming or trunk appendages. Spermatids are flagellate with a 9 + 2 microtubular arrangement. As they mature and move posteriorly they are packages into spermatophores.
To date, nothing is known about remipede development. Small juveniles have been collected which resemble adults. They are about one-third or less the length of adults."

Evolutionary Origins: The large number of trunk segments, each with similar, laterally directed, biramous, swimming appendages, plus a combination of the other characteristics necessitated the erection of a new crustacean class, the Remipedia (Yager, 1981). Remipedes are believed to be the most primitive of living crustaceans. The fossil species Tesnusocaris goldichi Brooks from Late Mississippian deposits in Texas has been placed in this class. The recent discovery of remipedes from anchialine caves in Western Australia is further evidence for a Tethyan distribution (Yager & Humphreys, 1996).

Conservation Status: Restricted to anchialine caves

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Contributor: Jill Yager, Antioch College, Yellow Springs, OH