How Many Spider Species Are There?

Spiders

Spiders are arachnids, a class of arthropods that also includes scorpions, mites, and ticks. There are more than 45,000 known species of spiders, found in habitats all over the world. There’s a spider with a cartoonish butt, spiders that can jump on demand, and cannibal spiders that look like pelicans.

Spiders range in size from the tiny Samoan moss spider, which is .011 inch long, to the massive Goliath birdeater, a tarantula with a leg span of almost a foot.

Harmful spiders?

For most people, the thought of spiders conjures up images of tarantulas, wolf spiders, and other (seemingly) fearsome creatures. Though all spiders have venom to one degree or another, only a handful are dangerous to humans. Those include the black widow and the brown recluse, both found in the United States.

The vast majority of spiders are harmless and serve a critical purpose: controlling insect populations that could otherwise devastate crops. Without spiders to eat pests harmful to agriculture, it’s thought that our food supply would be put at risk.

How spiders eat and hunt

Most species are carnivorous, either trapping flies and other insects in their webs, or hunting them down. They can’t swallow their food as is, though—spiders inject their prey with digestive fluids, then suck out the liquefied remains.

Though not all spiders build webs, every species produces silk. They use the strong, flexible protein fiber for many different purposes: to climb (think Spider Man), to tether themselves for safety in case of a fall, to create egg sacs, to wrap up prey, to make nests, and more.

Most spider species have eight eyes, though some have six. Despite all of those eyes, though, many don’t see very well. A notable exception is the jumping spider, which can see more colors than humans can. Using filters that sit in front of cells in their eyes, the day-hunting jumping spider can see in the red spectrum, green spectrum, and in UV light.

Threats

The greatest threat to spiders is habitat loss, although some spider species are also threatened by the pet trade.

World’s Largest Spider The goliath birdeater tarantula of South America is arguably the biggest spider in the world. Watch as one hapless mouse wanders into a spider’s deadly trap, and see the unusual adaptations that make the goliath one of nature’s deadliest ambushers.

www.nationalgeographic.com

Types of Spiders & Spider Facts

All spiders are predatory eight-legged creatures that have organs to spin silk at the back ends of their bodies. They are the largest part of the Arachnid family, a group that also includes scorpions and ticks. Spiders all have the ability to bite with venom-injecting fangs to kill prey and nearly all of them are poisonous (even if it’s just a little).

There are about 40,000 types of spiders in the world, living on every continent except Antarctica. And they’re not newbies: fossilized spiders have been found in Carboniferous rocks dating back 318 million years.

Spider anatomy

Spiders have two body segments, the abdomen and the cephalothorax. The first, or front part, is the cephalothorax, which is formed by the fusing of the head and thorax, according to Jo-Anne Nina Sewlal, an arachnologist at the University of the West Indies in Trinidad. The cephalothorax contains the eyes, mouth and legs.

The mouth has several parts. The spider’s jaws, called the chelicerae, are tipped with fangs, according to entomologists at the University of Kentucky. These appendages are used to hold prey while the spider injects venom. Behind the jaws are the labium and labrum, which work together to direct food into the spider’s mouth.

Between the chelicerae and the first pair of legs are the pedipalps, which look like tiny legs but are actually similar to antennae, and are used to sense objects the spider encounters, Sewlal said. However, «they are used by some species in prey capture and feeding as well as in shaping their webs.»

See also:  What Happens When You Get Bit By A Spider?

Pedipalps are also used in mating and are a good way to tell males and females apart. «The tips in males are enlarged as they are used to transfer sperm to the female, while in the female, the tips of the pedipalps remain undifferentiated,» Sewlal said.

Most spiders have six or eight eyes, according to the University of Kentucky. Some spiders can only see the difference between light and shadow. Their eyes are considered «simple,» as they don’t have compound lenses as some insects do.

A spider’s abdomen is where most of its important internal organs are located, such as the reproductive system, lungs and digestive tract. Also on the abdomen are the spinnerets, through which a spider produces its silken web.

Spider webs

Spider silk is made of strong strands of protein. It is the strongest-known natural fiber, according to the San Diego Zoo. Its tensile strength — the greatest stress a material will tolerate before breaking — is greater than bone and half the strength of steel.

According to the Smithsonian Museum of Natural History, individual species can produce up to seven distinct types of silk, each with a specialized function. Some spiders use their webs to trap prey; others line their burrows with it.

Spiders are grouped according to the type of web they make, according to the San Diego Zoo. Groups include tangle-web spiders, orb-web spiders, funnel-web spiders and nursery-web spiders.

According to the Australian Museum, spiders capture prey using a variety of methods. They can trap small insects in sticky webs, lasso them with sticky bolas, or use their vibration-sensing skills to chase prey down. Spider guts are too narrow to take solids, so they liquidize their food by flooding it with digestive enzymes and grinding it up with short appendages.

Spider bites

Even though all spiders can bite, most of them do no more harm to a human than a bee sting or a mosquito bite. Most spiders with a life-threatening bite are quite shy and attack only when they feel threatened. According to Spider Physiology and Behaviour, Volume 41 (Advances in Insect Physiology), there were only about 100 deaths from spider bites during the 20th century.

According to Sewlal, spider venoms work on one of two fundamental principles: they either attack the nervous system with neurotoxic venom, or attack tissues around the bite with necrotic venom. Sewlal explained that neurotoxic venom works in two ways: by overstimulating «the production of the neurotransmitters . which can cause the entire nervous system to become paralyzed,» and by blocking «nerve impulses to the muscles. This has the result of causing the muscles to cramp and become rigid. It also has the effect of disrupting many bodily functions.» Necrotic venom works by causing «the tissue around the bite to die.»

Researchers are investigating novel uses for spider venom, from an eco-friendly (and bee-friendly) alternative to pesticides, to treatments for Alzheimer’s disease, cardiac arrhythmia and strokes. In addition, spider silk has lots of engineering uses, from body armor to optical communications.

Arachnophobia

Humans have long had a tumultuous relationship with the eight-legged critters. Arachnophobia, or fear of spiders, is one of the most common phobias. Some statistics show that 50 percent of women and 16 percent of men have this phobia, according to The Wall Street Journal.

According to Mentally Healthy, evolutionary biologists surmise that a modern fear of spiders may be an exaggerated form of an instinctive response that helped early humans to survive. Other scholars think that fear of spiders began in the Middle Ages, when spiders became a cultural scapegoat for inexplicable epidemics of the time, like the plague.

Classification/taxonomy

According to the Integrated Taxonomic Information System (ITIS), the taxonomy of spiders is:

Can you imagine yourself holding this tarantula? (Image credit: Shane Wilson LinkShutterstock)

  • Kingdom: Animalia
  • Subkingdom: Bilateria
  • Infrakingdom: Protostomia
  • Superphylum: Ecdysozoa
  • Phylum: Arthropoda
  • Subphylum: Chelicerata
  • Class: Arachnida
  • Order: Araneae

Suborders

According to Sewlal, spiders can be divided into two suborders: Mesotelae and Opisthothelae, which contains the infraorders Mygalomorphae and Araneomorphae.

Mesothelae: «The suborder Mesothelae contains only one family, Liphistiidae,» Sewlal said. «The members of this family are quite distinctive from all other spiders.» She explained that the Mesothelae suborder is so named because its members have their spinnerets located on the middle of the abdomen, on their underside. According to the Australian Museum, these are «primitive spiders»; «modern» spiders have spinnerets toward the back of their abdomens. They also have abdomens segmented similarly to scorpions, Sewlal said.

See also:  What Happens If You Get Bit By A Wolf Spider?

These small, light spiders reside in Southeast Asia, China and Japan. Though scientists previously thought they lacked venom glands, new research has shown that they do have them.

Opisthothelae: These spiders have spinnerets at the posterior of their abdomens, Sewlal said. She offered some advice on how to distinguish between the infraorders Mygalomorphae and Araneomorphae: Look at the position of the chelicerae. «Araneomorphs have chelicerae where the tips crisscross each other, while mygalomorphs have chelicerae that point downwards like that of the typical vampire and move in the vertical plane.» Their book lungs — respiratory organs so named because their thin membranes resemble pages in a book — are also different. «Mygalomorph spiders also have two pairs of book lungs while araneomorph spiders have one pair of book lungs or no book lungs at all.»

Here are some other features of the two infraorders.

Mygalomorphae: According to Arachne.org, these spiders are generally heavily built and hairy, like tarantulas. They live in burrows, and can prey on creatures as large as frogs, lizards and snails. A few species build webs, but it is not very common. Although most spiders live for at most two years, many mygalomorphae spiders can live up to 25 years in captivity. This type of spider includes the huge goliath birdeater, which can grow up to 1 foot in body length, according to the Conservation Institute.

Araneomorphae: These are the most common of spiders, making up more than 90 percent of all the species, according to Biology of Spiders. Some of the most interesting species include the only known vegetarian spider, the Bagheera kiplingi, as well as the most venomous spider, the Brazilian wandering spider. Scientists have found that the spider needs to inject only 6 micrograms of its venom to kill a 20-gram (0.7 ounces) mouse, and a full venom load is more than 10 times that.

Katherine Gammon contributed to this article.

Editor’s Note: If you’d like more information on this topic, we recommend the following book:

Additional resources

  • Learn more about Jo-Anne Nina Sewlal’s research into orb-weaving spiders.
  • Explore the Australian Museum’s collection of spiders and other arachnids.
  • Find more fun facts about spiders at the San Diego Zoo.

Learn facts about these popular spiders:

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How Many Spider Species Are There?

Amongst the vast numbers of invertebrate animals in the Phylum Arthopoda, more than a million different kinds have bodies with three main parts—head, thorax, and abdomen. The head has eyes, antennae and mouthparts. The thorax has three pairs of legs. The entire body is protected by a tough outer covering called an exoskeleton. Animals that share these characteristics are called insects. The group to which they belong is called the Insecta.

Another, smaller, group of invertebrate animals has only two main body parts. The body consists of a combined head and thorax called the cephalothorax, and the abdomen. The cephalothorax has the eyes, mouthparts (no antennae) and four pairs of legs. Animals that share these characteristics include ticks, mites, scorpions and spiders. The group is called the Arachnida.

They have a very superficial similarity to spiders in that they have 4 pairs of legs but their legs are stilt-like and are kept bent with the body close to the ground. The daddy long-legs eats insects and other invertebrates as well as the tender gills of fungi and soft decaying matter.

See also:  When To Go To The Er For Spider Bite?

www.explorit.org

Spider Species

How many species of spiders exist?

Did you know there are more than 40,000 species of Spiders found in the world? Even though there are many similarities among them they are diverse enough to gain their own further categories. That can make it very hard to identify what type of Spider you happen to be in contact with. As a general rule most people just shy away from any type of Spider must in case.

All Spiders have 8 legs and at least 4 pairs of eyes. Some of them have extra pairs of eyes. It is said that all species also have the ability for the young to regenerate a limb if it is broken off. Yet the adults won’t have this ability so that can be a danger if they are trapped or attacked by a predator.

Only a very small number of Spider species have venom strong enough to harm a human. Some of them feel like a bee sting and others will make you very ill. It is a myth that a spider can kill you in seconds. Yet such rumors continue to be a huge part of what circulates in various types of materials out there.

There is plenty of variety among Spider species when it comes to their coloring. The stripes and bright colors help them to have a type of defense for hiding in plain sight in their natural habitat. By learning about the various color schemes you can also find out what species of Spiders pose a real threat to you.

In general most people don’t like Spiders. They often miscategorized them as a type of insect. They don’t belong to that group though due to the fact that they lack antennae. Experts love to study various types of Spiders to see why they act a certain way. However, we don’t have all the answers yet.

For example why do some Spiders create a web one way and then others do it differently? Why are some females known to consume the males after mating? All Spider species live on their own too so they don’t have any real need for socialization like so many other living things in the world do.

On average most Spider species have a very short lifespan. This can be about 2-3 years in the wild. Yet they can live for more than 10 years in captivity. It just goes to show you that there is definitely a difference between their living conditions out there in the wild that makes it had to survive even as an adult.

Chilean Rose Tarantula – Grammostola rosea

There are many different predators out there that feed on various Spider species. They include wasps, birds, toads, monkeys, and lizards. What will be a threat really depends on the species of Spider and the location. Even though Spiders move slowly, they do have some natural defenses that help them to have a fighting chance of escaping.

All Spider species are able to contribute to the environment. They take care of many volumes of insects. Without them feeding on them we would no doubt have an epidemic of them being a nuisance. Yet most people are more willing to get rid of Spiders than they are to take care of various insects around them.

The future is very uncertain for some species of Spiders. This is due to the fact that they are being depleted of their environment. Yet getting a good count regarding how many of them remain is also difficult. There aren’t many people out there though with a desire to help improve the living conditions for the various Spider species.

www.spidersworlds.com

The 10 Most Dangerous Spiders in the World

Learn to identify the most dangerous web crawlers in the outdoors

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