Endangered spiders
Encyclopedia
An endangered
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...

species is “a species at risk of extinction because of human activity, changes in climate, changes in predator-prey ratios, etc., especially when officially designated as such by a governmental agency such as the U.S. Fish and Wildlife Service”http://www.Dictionary.com. A spider
Spider
Spiders are air-breathing arthropods that have eight legs, and chelicerae with fangs that inject venom. They are the largest order of arachnids and rank seventh in total species diversity among all other groups of organisms...

is a member of the order Araneae, one of many orders within the class arachnid
Arachnid
Arachnids are a class of joint-legged invertebrate animals in the subphylum Chelicerata. All arachnids have eight legs, although in some species the front pair may convert to a sensory function. The term is derived from the Greek words , meaning "spider".Almost all extant arachnids are terrestrial...

a, meaning it has a body consisting of two segments, a cephalothorax
Cephalothorax
The cephalothorax is a tagma of various arthropods, comprising the head and the thorax fused together, as distinct from the abdomen behind. The word cephalothorax is derived from the Greek words for head and thorax...

 and an abdomen
Abdomen
In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...

, as well as eight legs. All spiders are predators that feed off insects, and some larger species have been known to catch small reptiles, birds, and amphibians (Levi and Levi, 2002).Until recently, insects and arachnids have not been considered for inclusion on threatened and endangered species lists. It was not until 1994 that most invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...

s were even recognized as being just as vulnerable as other fauna
Fauna
Fauna or faunæ is all of the animal life of any particular region or time. The corresponding term for plants is flora.Zoologists and paleontologists use fauna to refer to a typical collection of animals found in a specific time or place, e.g. the "Sonoran Desert fauna" or the "Burgess shale fauna"...

. It is because of this that there are very few species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of spiders listed as threatened or endangered and many are simply classified as “undetermined” http://www.iucnredlist.org.

Listed species

While few organizations agree completely on which spiders are endangered or threatened, a few commonly listed species are the Spruce-fir moss spider
Spruce-fir moss spider
The Spruce-fir moss spider, Microhexura montivaga, is an endangered species of spider found at high elevations in the southern Appalachian Mountains. First identified in 1923, they inhabit moss that grows on rocks underneath the forest canopy....

, the Dolloff cave spider
Dolloff cave spider
The Dolloff cave spider is a spider native to the west coast of North America.This species was listed on the 2000 IUCN Red List of Threatened Animals...

, the Great raft spider
Great raft spider
The great raft spider or fen raft spider is a European species of spider in the Pisauridae family. Like other Dolomedes spiders, it is semi-aquatic, hunting its prey on the surface of water...

, the Kauai cave wolf spider, the Katipo
Katipo
Latrodectus katipo, the katipo, is an endangered species of spider native to New Zealand. A member of the genus Latrodectus, it is related to the Australian redback spider, and the North American black widow spiders. The species is venomous to humans, capable of delivering a comparatively dangerous...

, and at a lower risk the Brachypelma smithi.

Spruce-fir moss spider (Microhexura montivaga)

This species is federally listed as endangered under the Endangered Species Act
Endangered Species Act
The Endangered Species Act of 1973 is one of the dozens of United States environmental laws passed in the 1970s. Signed into law by President Richard Nixon on December 28, 1973, it was designed to protect critically imperiled species from extinction as a "consequence of economic growth and...

 of 1973. This spider resembles a tiny “tarantula
Tarantula
Tarantulas comprise a group of often hairy and often very large arachnids belonging to the family Theraphosidae, of which approximately 900 species have been identified. Some members of the same Suborder may also be called "tarantulas" in the common parlance. This article will restrict itself to...

” with adults measuring in at only 2.5 to 3.8 millimeters. This particular species inhabits high-elevation forests in western North Carolina
North Carolina
North Carolina is a state located in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties. Its capital is Raleigh, and its largest city is Charlotte...

 and eastern Tennessee
Tennessee
Tennessee is a U.S. state located in the Southeastern United States. It has a population of 6,346,105, making it the nation's 17th-largest state by population, and covers , making it the 36th-largest by total land area...

. The species is extremely vulnerable to desiccation
Desiccation
Desiccation is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic substance that induces or sustains such a state in its local vicinity in a moderately sealed container.-Science:...

, causing it to shelter in damp shady areas such as shaded moss. The spider builds a tube shaped web between the moss and a rock or fir tree (Fish and Wildlife service, 1995), hence the name.

Dolloff cave spider (Meta dolloff)

While not listed as endangered, this spider is considered to be vulnerable to extinction
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...

. Much larger than Microhexura montivaga, this spider ranges in size from 10 to 15 millimeters. This species makes large orb shaped webs at the entrance of caves and as of 2001 has only been found in caves located in Santa Cruz, California
Santa Cruz, California
Santa Cruz is the county seat and largest city of Santa Cruz County, California in the US. As of the 2010 U.S. Census, Santa Cruz had a total population of 59,946...

 (Ubick, 2001).

Great raft spider (Dolomedes plantarius)

The Great raft spider ( also known as the Fen raft spider) is a declining species and is listed as vulnerable
Vulnerable species
On 30 January 2010, the IUCN Red List of Threatened Species identified 9694 Vulnerable species, subspecies and varieties, stocks and sub-populations.-References:...

. It occurs throughout Europe but a lack of records make assessment of the species difficult. In the UK there are only three known populations, one stable, one threatened and one not assessed. This spider is a semi-aquatic species and its dependence on water may have led to the population's decline. The information on the Gen raft spider is very recent and due to a lack of historical records, the level of decline cannot be accurately measured (Smith, 2000).

Kauai cave wolf spider (Adelocosa anops
Adelocosa anops
The Kauai cave wolf spider , 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 in the Kōloa–Poipū region of Kauai, Hawaiian Islands, and only six populations are known to exist. While their nearest surface-dwelling relatives...

)

This spider is found only on the Hawaiian island of Kauai
Kauai
Kauai or Kauai, known as Tauai in the ancient Kaua'i dialect, is geologically the oldest of the main Hawaiian Islands. With an area of , it is the fourth largest of the main islands in the Hawaiian archipelago, and the 21st largest island in the United States. Known also as the "Garden Isle",...

. In fact, as of 2006 this species can be found in one cave on that island and only 16 to 28 individuals have been encountered. Compared to other spider species, the Kauai cave wolf spider has a low reproductive rate and, due to habitat constraints, has little access to food sources (Fish and Wildlife service, 2006). This spider is one of the largest documented cave-dwelling organisms measuring up to a massive 8 centimeters. Because it spends its life in the darkness of a cave, this spider has no need for sight and is therefore completely eyeless (Krajick, 2001).

Katipo (Latrodectus katipo)

This spider is related to the Australian Redback and other Widow Spiders. This spider can be found in New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

 in burrows or in some trees. The name actually means "night-stinger". If you get bitten there is anti-toxin in New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

. They're endangered because other spiders are taking their homes.

Mexican Redknee Tarantula (Brachypelma smithi)

This spider is not endangered, it is actually at a lower risk but very close. This spider is a tarantula in the Brachypelma
Brachypelma
Brachypelma is a genus of the family Theraphosidae containing various species of tarantulas.-Characteristics:The species are native to parts of Central America. Habitat destruction and pet-trade collection has led these spiders to be among the few arthropods protected under the international CITES...

family.
The 'Redknee' used to be exported in large numbers from Mexico, long before we ever knew of their longevity, and so it was felt that, given the large numbers taken from the wild, and the length of time taken for these tarantulas to mature, a ban in Mexico would help to re establish the spiders in Nature again.
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