Biological Diversity 2006 

Image of Kaua'i Cave Wolf Spider LINK

Classification
Kingdom: Animalia
Phylum: Arthropoda
Class:
Arachnid
Order: Araneae
Suborder: --
Family: Lycosidae
Genus: Adelocosa
Species: Anops
Subspecies: --

Hawaiian Insect Names

Chart of the Hawaiian names of many insects on the islands, including A. anops.

Photo courtesy of William Mull

 

Some Sweet Tunes...

The Itsy Bitsy Spider

 

Noho (Hawaiian music)

 

Conservation Links

IUCN Red List of Threatened Species

Page for A. anops on the IUCN Red List, on which it is listed as threatened.

 

US Environmental Protection Agency - Endangered Status for A. anops & S. koloana

In-depth report by the US Fish & Wildlife Service (USFWS) about A. anops and S. koloana, discussing issues with the habitat as well as general information on both organisms.

 

USFWS Endangered Species Program

Main page of the US Fish and Wildlife Service, which provides a listing of all species they consider endangered and links to additional information.

 

USFWS Species Profile for Kaua'i Cave Wolf Spider

Provides links to all the current information regarding the endangered status of A. anops.

 

USFWS Recovery Plan

A detailed report on how the USFWS plans to recover and/or protect A. anops in its endangered status.

 

NatureServe Comprehensive Species Report on A. anops

In depth report on the status of A. anops, with references to its life history, its habitat, its distribution, and its viability.

 

Born Free

Page containing various links to many other wildlife conservation organizations and related information.

 

CITES (Convention on International Trade in Endangered Species of Wild Flora and Fauna)

Main page of CITES, which provides information on species put at risk by interational trade. Neither A. anops nor S. koloana are listed by CITES because neither organism is traded internationally.

 

Adelocosa anops -

Kaua'i Cave Wolf Spider

In 1971, scientists discovered a new member of the species Lycosidae, or wolf spider—Adelocosa anops. Commonly referred to as the Kaua’i Cave Wolf Spider or the No Eyed-Big Eyed Spider, this particular wolf spider is a unique and complex creature. The Hawaiian name for this spider is pe'epe'emaka'ole

Habitat * Structure & Adaptations * Reproduction * Conservation Status * Conservation Issues * Classification

 

Habitat
Adelocosa anops lives in a series of caves on the oldest of the main islands of Hawaii, Kauai, formed between 3.6 and 5.6 million years ago from a single volcano that is part of the modern day Alakai Plateau. Since 1971, A. anops has been observed in only five caves in the Koloa district in the southeast corner of Kauai, which includes the town of Koloa and the residential and resort area of Poipu.

Map of the island of Kaua'i, with the habitat of A. anops highlighted LINK

Rock in the Koloa district was formed during secondary eruptions between 0.6 and 1.4 million years ago. It is the only area in which caves are commonly found, due to the younger rocks, relative lack of developed soils, and minimal rainfall that causes sedimentation. Basalt is not as soluble as limestone, so the caves are more prone to filling with sediment and decreasing in size than typical limestone caves. Additionally, basalt will shrink and crack as it cools, forming an abundance of mesocaverns in the rock that are habitats or corridors between habitats. Over time, the mesocaverns are subject to sedimentation and are destroyed, decreasing the amount of available habitats.

The general structure of a cave habitat is highly zonal. Each zone exists with certain conditions which determine the type of organisms that will live within the zone. Not all caves contain all five zones.

Zone Light Notes Climate
Entrance Zone High Many surface plants Influenced by daily cycles of warming and cooling, humidity, and air exchange with upper zones and the surface
Twilight Zone Moderate Fewer surface plants
Transition Zone Low Greatly influenced by outside factors
Dark Zone None Narrowing cave passages, low ceilings Lack of air exchange with upper zones causes seasonal rather than diurnal temperature changes
Stagnant Zone None Gas composition controlled by organic decomposition (high CO2 & low O2) Very little air exchange with upper zones

Other general features of cave habitats include a limited food supply, with the food web based upon surface plants. Additional nutrient sources are available in water from underground streams or surface runoff or in the waste products of animals dwelling in the caves, like bats, birds, or rodents. Most Hawaiian caves are dependent on plant roots that penetrate the caves as the major nutrient source.

A. anops has been found only in damp, humid mesocaverns in the dark and stagnant zones of caves less than 100 feet above sea level in the Koloa district. The carbon dioxide levels can be greater than 3% by volume, and the temperature is warm, usually around 75-80°F. The wolf spider has been observed in only five caves in the Koloa district; in three caves it has been spotted on three occasions, while it has been seen more frequently in the other two caves. One cave has between 14-28 individuals during every observation between January 1996 to June 2001, while the other cave has shown 1-4 individuals up until April 2000, when no wolf spiders were observed in the cave. It is likely the lack of spider sightings in the caves is due to many factors contributing to a sub-optimal environment.

Structure/Special Adapations
Adults are about 12.7-19.0mm (0.5-0.75in) in total body length. They have a reddish-brown carapace, pale or silvery abdomen, and beige or pale orange legs. Four pairs of ventral spines are present on the tibiae of the two front leg pairs while unusually long, silky, and shiny sensory hairs called trichobothria are located on the tarsi (ultimate segments) and metatarsi (penultimate segments) of all legs. Three large teeth are arranged around each of the chelicera (biting jaw), one at the outer end and the other two located basally.

Image of general spider anatomy LINK

The most remarkable feature of A. anops is its eyes, as seen in its curious name of the No Eyed-Big Eyed Spider. Most wolf spiders are characterized by a distinctive eye pattern of two large eyes located within the middle row of eight eyes. While some species of Lycosidae have reduced eyes, only A. anops completely lacks them.

Image of A. anops, close up on the eyes LINK

As a predator, A. anops actively stalks its prey through chemo-tacticle sensory organs. Its likely food source is the Kaua’i Cave Amphipod (Spelaeorchestia koloana) and other arthropods.

Image of chemo-tacticle sensors LINK

S. koloana, the Kaua'i Cave Amphipod, is also an endangered species. It is small, around 7 to 10mm in length, and is also highly adapted to cave life. It has no pigmentation in its epidermis, making it nearly translucent. It has reduced swimming legs (pelopods) seen in related taxa and like A. anops, its eyes are completely absent. S. koloana is known to feed on roots of plants that enter the caves and rotting matter as well as arthropod feces. Though it is postulated to the one of the main food sources for A. anops, the amphipod is more frequently found in caves without the wolf spider. It has been observed to co-exist with other non-native arthropods, like cockroaches, wood lice, and small spiders.

Image of S. koloana LINK

Although it has not been proven true for A. anops, it is likely the wolf spider has a great tolerance for high humidity. It is found in high humidity zones in caves, and studies done in the past have shown that troglobitic (obligate cave dwellers) species of Hawaiian crickets have much higher evaporation/dessication rates than their relatives on the surface. A low dessication threshold places the troglobites in the dark and stagnant zones where the air is more humid. Trogliobitic faunas have also exhibited the same trait.

Similarly, experts hypothesize that A. anops is adapted to deal with the low oxygen levels and high carbon dioxide levels of the dark and stagnant zones, based upon laboratory experiments and observations in known stagnant zones. One experiment showed the surface dwelling Lycosa sp. required 2.5 times more oxygen than the cave dwelling Lycosa howarthi.

Reproduction
Very low reproduction rates are seen in A. anops—rates less than one-tenth that of other Lycosidae. Only 15-30 eggs are produced in each egg sac, which is incredibly low fecundity when compared to the 100 or more eggs produced by other wolf spiders. Female spiders carry their egg sac in their mouth until the fully developed offspring hatch.

A. anops hatchlings are generally larger than in other species, and like other species the spiderlings hang onto their mother with the specialized comb-like teeth on their claws. These teeth are specialized to fit perfectly onto the multi-branched hairs on the mother’s back. This lock-and-key attachment provides the spiderling with safe transport and protection during the first few days of life. In little over a year, the spiderlings develop into mature adults.

Image of A. anops mother with hatchlings on back LINK

 

Conservation Status

A. anops has been listed as Endangered by the US Environmental Protection Agency (US EPA) since January 14, 2000, as has S. koloana, the Kaua'i Cave Amphipod.

A. anops has been listed as EN B1+2c by the International Union for the Conservation of Nature and Natural Resources (IUCN) since 1983. This means that the organism is Endangered (EN), which indicates their belief the organism has a high risk of becoming extinct in its natural environment in the near future. The B1 designation expands on the Endangered status, stating the population is "severely fragmented or known to exist at no more than five locations". The 2c designation indicates there is a "continued decline, inferred,observed or projected in the area, extent and/or quality of the habitat".

 

Conservation Issues

Many conservation issues are tied to A. anops. There is a general lack of taxonomic knowledge about Hawaiian spiders, which are incredibly diverse due to the island geography fostering small populations in highly localized habitats. Population fluctuations are more frequent in A. anops, due to the relatively short life span of spiders, its low fecundity, and the occurrence of unpredicatable events, like natural catastrophes. Small populations can cause spiders like A. anops to be more vulnerable to the dangers of inbreeding, since their genetic pool is greatly reduced and therefore may result in an inferior ability to adapt to environmental changes.

Perhaps one of the most important conservation issues is the habitat of the wolf spider. Because A. anops has such a limited distribution, its habitat is essential to its life. For this reason, some of the major factors affecting Hawaiian spiders include habitat disturbance and invastion of alien species.

Threats to the Habitat
1. Caves in which A. anops has been found are all on privately owned land that is being either developed or used for agriculture. Human activity on the land is greatly affecting the delicate environment of the caves and has dramatic repercussions on the wolf spider. Examples of the effects of human activity include the removal of vegetation, thus affecting humidity levels and the existence of food sources (the amphipods). Development of the land can also affect air exchange in the habitat, change water and food infiltration patterns, and introduce pollutants. It can also increase the rate of sedmentation of the caves, filling the mesocaverns in which the wolf spiders live.

2. The presence of non-native competitors and predators decrease the survival rate of A. anops by decreasing the food supply available to the wolf spider and by decreasing the numbers of reproductive wolf spiders. The presence of alien invaders can upset the delicate environment in a multitude of ways, from food sources to water and air supply to reducing the amount of habitat available for the wolf spider.

3. Humidity levels are affected by droughts. Changes in humidity levels will affect fauna and animal life in each cave zone.

4. The use of pesticides and biological control agents on the land above the caves can enter the habitat through water and affect both plant and animal life.

5. Visitation by humans can upset the habitat in various ways, such as vandalism, destruction, or instances of unintentional take.

Conservation Actions
In 2003, the US Fish and Wildlife Service has designated 227 acres as a critical habitat for A. anops and the Kaua'i Cave Amphipod, which is a small fraction of the 4,193 acre habitat initially proposed in 2002. A critical habitat is "the specific areas within the geographic area occupied by a species, at the time it is listed in accordance with the Act (referring to the Endangered Species Act of 1978), on which are found those physical or biological features essential to the conservation of the species and that may require special management considerations or protection; and, specific areas outisde the geographic area occupied by a species at the time it is listed, upon a determination that such areas are essential for the conservation of the species."

Designation of a critical habitat will greatly aid conservation of both the habitat and the organisms within it, including A. anops and the equally endangered amphipod, S. koloana. It will allow a focused effort of conservation by identifying areas with physical and biological features essential to the conservation of both endangered species. These areas may require special management considerations or protection, such as protection from human and other intruders. Human activity around the caves is being monitored to prevent as little effect on the habitat or the wolf spiders as possible. For example, the Kiahuna Golf Course is located directly above one of the most biologically diverse of the Kaua'i caves. Over 30 different pesticides are commonly used on Hawaiian golf courses--including organophosphates and carbamates that often have dramatic physiological effects. In addition to protection from future invasions of alien species, conservation actions include controlling the current non-native populations that might affect A. anops and attempting to restore or enchance the cave habitat by methods like outplanting the caves with native species, which would stabilize the environment and increase the amount of food sources available to the amphipod. Another significance of the critical habitat designation will bring the importance of the area and the status of the wolf spider to the attention of the public and land managing agencies.

 

Literature Cited


ARACINS - Morphology.
<http://www.geocities.com/rainforest/vines/5197/morphology.html>
Accessed on 28 February 2006.

Chamberlain, Ted. Photo in the News: Rare Baby Spiders Ride Mom's Back. National Geographic.com
<http://news.nationalgeographic.com/news/2006/01/0127_060127_spiders.html>
Accessed on 25 March 2006.

Comprehensive Report Species - Adelocosa anops.
NatureServe Explorer. <LINK>
Accessed 28 February 2006.

Focus on Adelocosa anops: Hawaii's Biodiversity & Mapping Program.
<http://www.hinhp.org/printpage.asp?spp=ILARA18010>
Accessed on 28 February 2006.

Gillespie, R.G.
Naivete and Novel Pertubations: Conservation of Native Spiders on an Oceanic Island System.
Dec 1999. J Insect Conserv 3(4): 263-272.

Hawaiian Insect Names. Bishop Museum.
<http://www.bishopmuseum.org/research/natsci/ento/database/HInsects.html>
Accessed on 26 March 2006.

Howarth, Francis G.
"Hawaiian Islands, Biospeleology". Encyclopedia of Cave and Karst Science.
<http://www.botany.hawaii.edu/faculty/morden/BotZoo450/Biospeleology.htm>
Accessed on 20 February 2006.

IUCN Red List - Categories and Criteria (version 2.3).
<http://www.redlist.org/info/categories_criteria1994#categories>
Accessed on 28 February 2006.

Lee, Jennifer.
"A Closer Look at Spiders of the Hawaiian Islands".
<http://spain.bol/ucla.edu/hawaiipg04.html>
Accessed on 28 February 2006.

Scientists Photograph Kauai Wolf Spiders.
CBS News.
<http://www.cbsnews.com/stories/2006/01/26/ap/tech/printableD8FC219O4.shtml>
Accessed on 23 March 2006.

Terrestrial Invertebrates: Kaua'i Cave Arthropods Adelocosa anops (Kaua'i Cave Wolf Spider), Spelaeorchestia koloana (Kaua'i Cave Amphipod).
Hawaii's Comprehensive Wildlife Conservation Strategy.
<http://www.state.hi.us/dlnr/dofaw/cwcs/files/NAA final CWCS/Chapters/
Terrestrial Fact Sheets/Inverts/Kauai Cave arthropods NAAT final !.pdf>
Accessed on 28 February 2006.

Pacific Islands - Endangered Species: Threatened and Endangered Animals in the Hawaiian Islands.
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<http://www.fws.gov/pacificislands/wesa/caveanimals.html>
Accessed 26 March 2006.

Endangered and Threatened Wildlife and Plants: Determination of Critical Habitat for the Kaua'i Cave Wolf Spider and Kaua'i Cave Amphipod.
US Fish and Wildlife Service.
<http://www.setonresourcecenter.com/register/2002/Mar/27/14671A.pdf>
Accessed on 28 February 2006.

What are the Effects of Golf Course Pesticides on Endangered, Cave Dwelling Arthropods?
<http://www.fws.gov/pacific/ecoservices/envicon/pim/reports/Hawaii/Golfcaves.html>
Acessed on 28 February 2006.

Wright, Amy. Kauai's Blind Cave Creatures Get Sanctuary.
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<http://www.hawaiinews.com/archives/science/000115.shtml>
Accessed on 26 March 2006.

 

Author: Chrysalis Kendall & Ashley Reyer
Creation/revision date:
3 April 2006


Earlham Biology Department Biology 226: Biological Diversity

Copyright -2001 Earlham College. Revised 1 March 2006