5 Most Endangered Spiders

No matter how you feel about these eight-legged creepy crawlies, there’s no denying that they play an important role in our ecosystem. They control various insect populations, prevent the spread of insect-borne diseases, and also serve as a food source for many animals. 

These fascinating yet feared creatures have existed for about 400 million years, but their populations were not evaluated for risk until recently. With a newfound interest in spiders and their role in our ecosystem, many scientists are just now recognizing how under-represented these creatures are in conservation plans around the globe.

In this article, we’ve compiled a list of endangered spiders that are at risk of extinction from all around the world for you. We’ll briefly go over their characteristics, scientific names, the places they inhabit, and the threats they face.

Important Note

An endangered species is one listed by the International Union for Conservation of Nature (IUCN) as being at risk of extinction because of human activity, climatic changes, changes in predator-prey ratios, etc. Spiders weren’t considered for inclusion on threatened and endangered species lists until recently, which is why there are few species of spiders officially designated as threatened or endangered by governmental agencies.

However, spiders too face the same challenges as other animals due to climate change, pollution, deforestation, etc. Some of them are extremely close to extinction and need to be conserved immediately.  

1. 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 – a system of mountains in eastern to Northeastern North America. It was first identified and categorized in 1923. It’s called a moss spider because it inhabits moss that grows on rocks underneath the forest canopy.

The spruce-fir moss spider is a small spider, with adults only measuring 3-4mm in length. Its color varies from light brown to yellow-brown to a darker reddish brown with no markings on the abdomen. It also possesses a second pair of book lungs, which appear as light patches behind the genital furrow. 

Death of the Fraser fir trees and thinning of the forest canopies have resulted in many spider habitats being destroyed. The thinning results in drying of the moss mats which are essential for the spider’s survival, as it requires climates of high and constant humidity. It inhabits the Appalachian Mountains falling in Tennessee and North Carolina. The population in Tennessee was considered healthy up to 1989 but has possibly died out since there have been no recorded sightings in the recent past.

In two locations in North Carolina, there was only one spider found each in recent years. The population in North Carolina seems to be stable but restricted to the moss mats on a single rock outcrop and a few surrounding boulders. 

This spider feeds on mites in springtails and is the top predator in its microhabitat. Scientists know that spiders play a significant role in controlling insect populations as top predators, so the extinction of one species could have a ripple effect on other spider species and ecosystems. The spruce-fir moss spider can take as long as three years to reach maturity due to which it has a low metabolism. 

2. Kaua’i Cave Wolf Spider

The Kaua’i cave wolf spider (Adelocosa anops), also known to locals as the blind spider, is an endangered species of spider only found in three caves in the Koloa Basin of the Hawaiian island of Kaua’i. These cave wolf spiders are also found in one experimental cave operated by the US Fish and Wildlife Service, called Cave 3075C.

Only six populations of the spider are known to exist and this species of spider has completely lost its eyes. They grow to a body length of around 20 mm and are reddish brown in color. They’re completely harmless to people. The spiders produce 15 to 30 eggs in one clutch and the female carries the eggs in her mouthparts until they hatch.

This spider was first discovered in 1973 and there has never been documentation of more than 30 individuals. It usually preys on the Kaua’i cave amphipod, which is the major part of its diet. It is a cave-dweller and prefers living in large cave passages and cracks that are inaccessible to humans. The spiders require a high-humidity habitat, which is why they prefer to inhabit the dark and stagnant air zones of caves that are characterized by high humidity, low air movement, and lesser temperature fluctuations. 

The major threats that the spider faces are habitat modification, novel competition, and chemical runoff. Their habitats are being modified largely due to human development. Construction projects expose caves to surface air and impact the subterranean environment.

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Novel species of spider also outcompete the native Kaua’i cave wolf spider for prey. Recreational exploration of caves by humans negatively impacts the delicate ecosystem of the cave as well and humans can expose the vulnerable life inside to many pathogens. 

3. Peacock Tarantula 

The Peacock tarantula (Poecilotheria metallica) is a critically endangered species of tarantula notable for its blue color and hair. It exhibits an intricate fractal-like pattern on the abdomen. The spider naturally inhabits and is native to the deciduous forest in Andhra Pradesh, a state in central southern India. It is only found in a small area of less than 100 square kilometers, a reserve forest that is highly disturbed and threatened by human activity.

In the wild, this tarantula lives in holes of tall trees where it builds asymmetrical funnel webs. It primarily preys on flying insects and is the top predator in its microhabitat. It is a skittish spider and will try to flee first upon confrontation. The spider is also photosensitive and will escape when light shines upon it. When provoked, however, the spider may bite to protect itself. Its venom is medically significant and can do critical damage.

When they’re fully grown, the spiders have a leg span of 15-20 cm. Males live for 3 to 4 years while females have been known to live for 11 to 12 years and for up to 15 years in rare instances. The Peacock tarantula is also being bred in captivity for over ten years and is a popular exotic pet among tarantula enthusiasts. An adult individual is priced above $500 in the United States and the spider’s sex can also influence the price – females are generally more expensive because of their longer life. Pet spiders generally feed on crickets, moths, grasshoppers, and cockroaches. 

The species is listed and classified as critically endangered by the International Union for Conservation of Nature (IUCN) because of its occurrence in only a single, small area. Its habitat is rapidly being extirpated due to logging and firewood harvesting. Another major threat identified by IUCN assessors is specimens being collected for the pet trade from the wild. Their population size is unknown, but their small natural range and the threats to their habitat indicate a downward population trend. 

Did You Know?

Just like silkworms, the webs that spiders produce to trap their prey and fearsomely dangle from our ceilings are called “spider silk.” Due to its unique structure, this material is stronger than steel while being 98% water. Since it is super elastic, it can be stretched many times before it snaps. Scientists have been trying to replicate its unique molecular structure for decades but haven’t quite managed to do that yet. This completely biodegradable material could also potentially revolutionize the textile industry.

3. Katipō

The katipo (Latroectus katipo) is an endangered species of spider that only inhabits New Zealand. It is a small to medium-sized spider, with the female having a round black pea-sized body. The mature female has a body size of about 8 mm with a leg span of up to 32 mm. The male is much smaller than the female – about one-sixth the size of an adult female, and quite different in appearance. They have a white abdomen with a series of red-orange diamonds running along the dorsal region bordered by irregular black lines.

Katipō is mainly found inhabiting sand dunes close to the seashore throughout most of coastal New Zealand except the far south and west. They generally reside on the landward side of dunes closest to the coast where they are most sheltered from storms and sand movement.

Katipo’s diet typically consists of ground-dwelling insects that it catches in an irregular tangled web spun amongst dune plants or other debris. Its prey includes ground invertebrates such as beetles or amphipods, but it may occasionally catch moths, flies, and other spiders. This spider can catch insects much larger than itself. The male has similar hunting behaviors to the female, though it may not be as vigorous due to its smaller size. The female katipo produces five or six egg sacs in November and the spiderlings hatch during January and disperse into surrounding dunes. 

This small spider has recently been listed as an endangered species and is threatened with extinction. Reports suggest that there are only a few thousand katipos left in the wild – making it rarer than some species of Kiwi. The major factor that has impacted its population is the loss of its natural habitat. Human interference in the form of agriculture, forestry, or urban development has been occurring for over two centuries and has resulted in changes to their habitat. Recreational activities such as the use of beach buggies, driftwood collection, and beach horse riding have also made changes to the areas the katipo inhabits. 

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4. Great Raft Spider

The great raft spider (Dolomedes plantarius), also known as the fen raft spider, is a European species of spider that inhabits Eastern and Western Europe, including the United Kingdom, Finland, Bulgaria, Russia, etc. It is listed and classified as a vulnerable species on the IUCN Red List.

The great raft spider is a semiaquatic spider that hunts its prey on the surface of the water. It is found mainly in neutral to alkaline unpolluted water and marshy grasslands. The spider is a large species among the others in its genus – with adult females being slightly over 20 mm in length and having a leg span of 70 mm. 

Great raft spiders are insectivores and hunt from perches at the water’s edge. Their diet primarily consists of aquatic invertebrates such as dragonfly larvae, small fish, and smaller aquatic spiders. They have also been known to catch sticklebacks and tadpoles. In order to hunt aquatic prey, they have developed a sensory system of chaetae, a covering of sensory hairs on their legs used to detect the ripples made as their prey moves through the water. They are also known to hunt underwater or go underwater to avoid predators.

These spiders have a lifespan of two and a half years. The female lays several hundred eggs in a silk sac, which they carry under their bodies for around three weeks until the spiderlings hatch. The spiderlings disperse into their surroundings usually five to nine days after hatching.

Despite being distributed on a wide scale within Europe, under-recording makes the assessment of its conservation status difficult. Its current status on the IUCN Red List is vulnerable and populations have declined significantly in the recent past. These reductions in population are majorly due to the degradation and loss of habitat. The loss and degradation of wetlands in general, and of lowland fens in particular, throughout much of its range has impacted populations significantly. Colonization by other spider species also poses a threat to the great raft spider population as it has to compete for prey with them. 

5. Dolloff Cave Spider

Brandon Sanchez / CC BY-SA 4.0

The Dolloff cave spider (Meta dolloff) is a spider native to California and among the rarest spiders of North America. Although it is not biologically modified for cave life, this species of spider only inhabits caves and cave-like habitats. It is found in the Empire Cave System near the University of California and other Californian caves in Santa Cruz and the Gray Whale Ranch State Park.

The Dolloff cave spider was listed on the 2000 IUCN Red List of Threatened Animals – the list that tracks animals that may become endangered. In 1996, it was listed by the United States Fish and Wildlife Service as a ‘critically imperiled’ species due to its constrained range. Its IUCN’s conservation status is vulnerable.

This arachnid is an exceptionally large spider and an adult could easily wrap their legs around a peach pit. It weaves broad-meshed orb webs near entrance areas to the twilight regions of the cave or cave-like habitats to catch its prey. The spider varies in color, ranging from orange, red, and light and dark brown. It is dark overall but has a lighter brown pattern on its abdomen. It has long spine-like legs with marks on its leg joints.

The Dolloff cave spider faces many threats in its microhabitat, but the major one is possibly human activity and development. The building of dams and reservoirs has greatly impacted the karst cave systems of the caves and altered the flow of nutrients into the caves.

Population and contamination of various chemicals also play a huge role in the species’ decline. Some cave systems like the Empire Cave System are regularly frequented by visitors and this disturbs the cave habitat. Tobacco smoke, spray paint, and damage to webs leave the spiders highly susceptible to going extinct. 

In Other News…

Despite this disheartening news about spiders and their conservation status, every dark cloud has a silver lining. After being widely misunderstood and neglected for centuries, scientists are finally taking an interest in the eight-legged black sheep of the animal kingdom. In recent news, scientists in Australia have discovered a giant species of Trapdoor spiders in a forest in Queensland. This species is the largest among Trapdoor spiders discovered so far.

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Nadine Oraby

My name is Nadine; I am a passionate writer and a pet lover. People usually call me by the nickname “Joy” because they think that I am a positive and joyful person who is a child at heart. My love for animals triggered me to create this blog. Articles are written by vets, pet experts, and me. Thanks for visiting. Your friend, Nadine!

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