Pacific Islands Fish and Wildlife Office
Pacific Region

Endangered Species in the Pacific Islands

Kauai Cave Arthropods: Kauai Cave Wolf Spider and Kauai Cave Amphipod

Photo of Kaua‘i cave wolf spider The Kaua‘i cave wolf spider was discovered in 1973 and is only know to occur in a few caves in the Koloa-Poipu region. They are closely related to surface-dwelling relatives which possess large, well developed eyes which help them hunt insects and other small animals, using their acute vision and agility to chase down their prey rather than relying on a web to entangle their next meal.
Kaua‘i cave wolf spider - Photo credit William Mull

The Kaua‘i cave wolf spider is so well adapted to cave-life that it, like other cave animals, has completely lost its eyes, giving it the often used alias, the "no-eyed, big-eyed wolf spider." Like all spiders, they are venomous, however their venom is of use only on small prey animals. They reach the size of a fifty cent piece, and are completely harmless to people.

Photo of Kaua‘i cave amphipod The Kaua‘i cave amphipod is a small crustacean (related to crabs and shrimp) that co-inhabit the cave habitats with the cave wolf spider. Unlike the wolf spider, they are not predators, but feed on plant material, primarily roots, and other decomposing matter found in caves. They are considerably smaller than the wolf spider, to which they may fall prey, measuring a total of around 10 millimeters.
Kaua‘i cave amphipod - Photo credit William Mull

Habitat & Behavior:
These two species exist in a predator-prey relationship in the inky blackness of moist lava tubes and adjacent crevices in the Koloa lava flows in southeastern Kaua‘i. Unlike most wolf spiders, it produces only 15 to 30 eggs per clutch. The female wolf spider exhibits parental care, carrying their egg sac in their mouth until their fully developed spiderlings hatch. After hatching, the new-born spiders ride on the back of their mother for a time before leaving her to live and hunt on their own. Only three populations of the Kaua‘i Cave Wolf Spider are known to exist.

The Kaua‘i cave amphipod feeds on the decaying roots of surface vegetation that reach into the cave system, as well as rotting sticks, branches, and other plant materials. This amphipod, which is believed to be one of the primary prey items of the Kaua‘i cave wolf spider, is known from only five populations.

Past & Present:
Both the Kaua‘i cave wolf spider and amphipod are threatened by habitat loss. Land modifications began with the arrival of the Polynesians and continues today through poorly planned land conversion for agriculture and development.

The two species are threatened by deterioration of their cave habitat caused by clearing, grading, filling, paving, and other activities associated with development and agriculture. They also are susceptible to the use of chemical and biological pest controls, which often are employed to control nonnative insects such as ants and cockroaches.

Conservation Efforts:
To ensure their survival into the future, a number of important caves have been provided with protected status by the landowners, including the caves below Kiahuna Golf Club.

The U.S. Fish and Wildlife Service has been working with the Kukui‘ula Development Corporation since 1995 to help restore and protect two caves on the company's property that provide habitat for these two endangered cave animals. The company has agreed to set aside the land area above these two caves as either a limited use park or reserve to further protect these species. The Service hopes to undertake similar partnerships with other private landowners. Final Recovery Plans for these species were completed July 19, 2006.


Last updated: September 20, 2012
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