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Spelaeorchestia koloana, the Kauai cave amphipod or ʻuku noho ana in Hawaiian, is a cave-dwelling crustacean endemic to the Hawaiian island of Kauai. It is eyeless and measures 7–10 mm (0.25–0.4 in) in length. The amphipod is only known to live in 8 caves and it eats decomposing material, such as decaying plant matter.

The main predator of the Kauai cave amphipod is the Kauai cave wolf spider, Adelocosa anops. This species was listed on the IUCN Red List in 1996, and then as endangered under the Endangered Species Act in 1999.

Description
Kauai cave amphipods have a few different appendages: a reduced pincher-like structure, a mitten-like structure, and some spiny parts. Adult amphipods are 7-10mm (0.25 to 0.4 in) in length, have a laterally compressed body shape, and lack eyes. They are shiny and translucent. Their walking legs (pereiopods) are long and slender with claws while their swimming legs (pleopods) are reduced. The uropod, or tail-like structure, is absent in adult females. In some specimens, there is one antennae or a possible antennal gland. Males are distinguished by penis structures on the bottom of the body. Many of these characteristics are adaptations to a dark, cave environment.

Life History
Nothing is known about the reproductive biology of the Kauai cave amphipod. The brood plates, or reproductive structures, of females suggest that they birth a small number of offspring. Males lack an appendage found in related species which is used to hold onto the female during mating.

Diet
Kauai cave amphipods are detritivores. Their observed diet includes: roots of Manila tamarind and fig plants, rotting roots, sticks, and branches. They also eat the feces of other arthropods and plant debris that wash into caves.

Behavior
Kauai cave amphipods are typically found in groups under roots or rotting plant debris. These amphipods are anemophobic, so when disturbed by wind, they will lie flat on the ground and leave after the disturbance. They have also been observed standing motionless, walking slowly, and swimming.

Habitat
Kauai cave amphipods are only found in caves in the Koloa Basin of Kauai, Hawaii. They have been observed in 8 caves within this region, but are only regularly found in 3. The temperature within the dark parts of these caves tends to be approximately 25℃ (77℉) and species resides in regions of the cave where the relative humidity is greater than 95%. Plant roots and other decomposing plant materials have been found within all the caves where the amphipods live. Within these caves, the amphipods live in small, dark, and moist cracks.

Range
This species is only found on the island of Kauai, Hawaii.

Population Size
Little is known about the population size of the Kauai cave amphipod. In 2006, researchers found 8-40 individuals in 3 caves. In one cave, they found over 300 individuals, but this might be due to periodic food enhancement by research biologists. In a 5 year review from 2017, scientists found about 20 individuals in 8 caves. A larger population may exist throughout the Koloa caves, but more research is needed.

Past and Current Geographical Distribution
In 2006, the amphipod was only regularly seen in 3 caves, however in 2017 that number increased to 8.

Major Threats
Human interactions with the amphipod’s habitat is a threat to the species. Development of the Koloa district, such as building roads, golf courses, and houses, leads to degradation of the cave habitat. Quarrying can destroy caves and reduce humidity levels. Droughts can also occur when cracks, which allow water to soak into caves, are filled by soil as a result of construction. Also, runoff from new developments can contain pesticides and enter the caves. Perennial plant s and the introduction of exotic plants to the caves also damages the habitat. Human visitation to caves can also cause issues when individuals are stepped on, trash is left, or scientists collect too many organisms.

Predation is another major threat to the Kauai cave amphipod. The introduction of non native species such as Nesticus mogera, violin spiders, scorpion species, and the ribbon worm has increased predation pressure. This increases the impact normal predation by the Kauai wolf spider has on the population size. Living organisms used to control pests can also be a new predator for the amphipods.

Life history traits of this species also could hinder their survival. They are a cave obligate species, which means they need cave habitat and have a very limited range. It is also hypothesized that they have low reproductive potential, which would make it more difficult to recover from natural disturbances, like hurricanes. Additionally, climate change changes the temperature and humidity of the caves and can cause more frequent weather events.

Listing Under the ESA
The Kauai cave amphipod was proposed to be listed under the Endangered Species Act as threatened in 1978. This proposal was pending, and then was removed in 1980. Scientists petitioned 9 more times until Kauai cave amphipod was listed as endangered in 1999.

5-Year Review
In 2006, the 5 year review found that the major threats to the Kauai cave amphipod had not been reduced. Their small population size and long list of threats mean that the amphipod should remain listed as endangered. Additionally, more funding is necessary to monitor these caves.

In 2017, the number of suitable amphipod caves increased from three to eight. This was a success but future actions remain. The US Fish and Wildlife Service plans to begin plant restoration above ground, work to control non-native predator entrance into caves, and add air blocks to regulate humidity.

Species Status Assessment
There is no species status assessment for this species.

Recovery Plan
The goal of the recovery plan, as recorded in 2006, is to 1) provide protection against threats and 2) manage the species to a point where it can be downlisted to threatened status, as opposed to endangered. This can be achieved when caves meet the following criteria:


 * 1) Each population has all ages and has a balanced sex ratio.
 * 2) Each population has a stable or increasing population size over a 10-year period.
 * 3) Each population is protected from stressors. These stressors include: nonnative species, predators, human visitation, pollution, etc.
 * 4) Caves and their surrounding above-ground habitat are managed and protected from future development. This includes the restoration of vegetation inside and around the caves.

Necessary Actions

 * Human interaction with these caves should be limited.
 * Habitats should be protected by improving above ground conditions, which will provide more food sources.
 * Research should continue to be gathered on the population size and location.
 * The public should be educated on this species and their habitat.
 * The recovery plan should occasionally be checked to see if objectives have been met.