The Kauaʻi cave wolf spider (Adelocosa anops, the only species in the genus Adelocosa), also known to local residents as the blind spider, is only known to occur in a few caves in a lava flow with an area of 10.5 km2 (4.1 sq mi) in the Kōloa–Poʻipū region of Kauaʻi, Hawaiian Islands, and only six populations are known to exist.[3] While their nearest surface-dwelling relatives have large eyes, this species has completely lost its eyes. They reach a body length around 20 mm (0.8 in), and are reddish brown and completely harmless to people.[4] Unlike most wolf spiders, it produces only 15 to 30 eggs per clutch. The female carries the egg sac in her mouthparts until the spiderlings hatch.[3]
One of its primary prey species is the Kauaʻi cave amphipod, Spelaeorchestia koloana, which is only known from nine populations and reaches about 10 mm (0.4 in) in length.[4] These feed on decomposing plant matter. The Kauaʻi cave wolf spider was discovered in 1973.[5] Counts have never documented more than 30 spiders or 80 amphipods.[4]
Adult Kauaʻi cave wolf spiders typically measure between 12.7 and 19.0 millimeters (0.5-0.75 inches) in length.[6] The Kauaʻi cave wolf spider is the only wolf spider to completely lack eyes.[7] It has a reddish brown to orange carapace with a pale abdomen and bright orange legs.[7] Each leg has four pairs of short black spines and a thin coating of pale, silky hairs.[7] The chelicera has three large teeth used for biting prey.[6]
Kauaʻi cave wolf spiders have a small clutch size compared to other wolf spiders. Kauaʻi cave wolf spiders only produce 15-30 eggs per clutch, whereas other terrestrial wolf spiders may have 100 to 300. Female Kauaʻi cave wolf spiders carry their egg sacs on their backs until their spiderlings hatch in 30 to 50 days. Upon hatching, the large spiderlings will be carried on the back of the mother for several days. Kauaʻi cave wolf spiders have an adapted row of comb-like teeth on their claws. These align perfectly with the branched hairs of their mother's back and allow the spiderlings to hold onto the mother securely for protection and transport.[8] This species takes up to a year to reach sexual maturity. At that time, the spiderlings are old enough to hunt for themselves and will disperse from the mother.[6]
Ecologists hypothesize that Kauaʻi cave wolf spider life history has been shaped by a behavior that allows other wolf spiders to fly through the air at short and long distances. Aerial dispersal is a behavior employed most often by young spiderlings, or instars, though it has never been observed in Kauaʻi cave wolf spiders.[9] However, there are close relatives to this species that are able to aerially disperse that inhabit the islands next to Kauaʻi. This suggests that Kauaʻi cave wolf spiders originated from an ancestor that came from other nearby Hawaiian islands.[7] Dispersal mechanisms and behaviors allow individuals in a population to avoid competition for resources, unfavorable environmental conditions, and predation. Utilizing aerial dispersal would be dependent on the trade-off between the costs of landing in an unstable environment and the benefits of finding a new environment with fewer constraints or threats.[9]
The Kauaʻi cave wolf spider is an opportunistic feeder, meaning it feeds on other cave inhabitants whenever possible. Its diet may include the Kaua'i cave amphipod, as well as introduced spiders and cockroaches.[8]