Spiders

Spiders

Spiders are arthropods i.e. animals that have a hard external skeleton and jointed limbs, and belong to a group of large invertebrates (animals lacking backbones) that have spinning glands used to produce silken threads and webs. Even though spiders and insects belong to the largest group of animals on Earth, they don’t belong in the same family.

spider
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It should be noted that spiders are carnivorous i.e. feed on the flesh of other animals. They can survive in almost any environment from cities to deserts and live in any continent except Antarctica.

 In most cases spiders are very shy, they rarely bite and always try to run away from danger, and opposed to widespread belief, the majority of spider bites are not dangerous to humans; of the thousands of spider species, only about 30 species produce bites that are lethal to man.

Nearly all spiders have eight eyes arranged in different ways, consisting of one lens and a retina. But most of them don’t see very well and rely on other senses, like smell and touch. Only about half of all spider species use the web to capture prey, while others hunt without webs. Most spider species live up to 3 years in wild and to 10 years in captivity.

An argyroneta aquatic spider lives under water.

There are about 40000 spider species and are categorized into 3 main categories:

  1. Mygalomorphae (Tarantula)

Most of these species come from Australia and some of them are poisonous to humans; we know them by common name ‘tarantulas’. Many of the species have hairs that if touched would result in an awful rash. Even though many of them possess venoms, their venom poisons isn’t as strong as people think, and are most similar to a bee sting.

They have a poor vision, so they rely on tactile senses and chemical (taste and smell). It is traditionally thought that these relatively ‘primitive’ spiders had simple sexual communication systems. They are also brave opportunists, and will attack anything that comes in front of them; even another spider.

  1. Araneomorphae or (True Spiders)

True spiders are the most common spiders’ species.  Their bite is not that harmful.  A host of these spider species have evolved from spiders who only spin webs and live in a fixed location, to spiders who wander around with developed hunting skills.  These species is renowned for wrapping its prey in silk. This family species can make a wide variety of silk. The most common members of this family are the wolf spiders, crab spiders and jumping spiders.  

  1. Mesothelae

Mesothelae is a family of spiders that includes the family Liphistiidae and extinct families; Arthromygalidae and Arthrolycosidae. As opposed to previous believe, they possess all venom glands and ducts that almost all other spider species have. All Mesothelae have eight spinnerets in four pairs, as all their ganglia are fused into one mass in the cephalothorax. Of all arthropods, these spiders have the most centralized nervous systems.

Video credit: Biggeststuffaround

The most common species are Kimura-gumo (Heptathela kimurai) and The Trapdoor spider (liphistius batuensis). 

 

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