Author Box
Articles Categories
All Categories
Articles Resources

A Look At The Characteristics of Spiders

April 02, 2012 | Comments: 0 | Views: 170

Spiders are generally feared by people, something that is common for many of us, when we see any kind of insect, not just this one. Knowing about something we fear helps liberate us though, so take a look at the information we have on spiders below.

Most arachnids share certain characteristics including a body divided into two parts, the cephalothorax or prosoma and the abdomen or opisthosoma; no antennae; chelicerae; a unique pair of appendages in the front of their bodies called pedipalps involved in feeding and/or mating; four pairs of walking legs; external digestion; indirect sperm transfer; elaborate courtship behaviors; a strict predatory lifestyle.

However, not all arachnids share all these characteristics. For example, the cephalothorax and abdomen of opilionids and acarines have become fused giving them the appearance of having only a single body part rather than the two characteristic of the other arachnid groups. Some species in these two orders also differ in having direct sperm transfer.

Some opilionids can digest solid particulate food and, therefore, do not rely solely on predigested, or externally digested, material. Opilionids and acarines also differ in that neither group is a strict predator. Opilionids are, for the most part, scavengers, whereas acarines can be predators, ectoparasites, or plant feeders.

Silk Production

Silk is characteristic of all spiders. Spider silk emerges from structures at the posterior end of the spider's abdomen called spinnerets. The proteinaceous material is produced in silk glands in the abdomen. As the silk protein is exuded through the tiny opening of the silk spigot on the surface of the spinneret, most of the water is re-absorbed.

The protein configuration completes its transformation from liquid to solid as the droplet of silk is stretched or put under tension. This can occur as the spider pulls the silk out of the spinnerets with a rear leg, or as the spider attaches the droplet to the substrate and walks away - these movements create enough tension to change the protein structure from liquid to solid.

Most spiders have three pairs of spinnerets - the anterior, the median, and the posterior pairs. However, it is thought that ancestral spiders had four pairs: an anterior lateral pair, an anterior median pair, a median pair, and a posterior pair.

Spiders in the suborder Mesothelae still have four pairs of spinnerets, but one pair (the anterior median) is nonfunctional and residual.

The anterior median pair has been lost and a rudimentary, non-functional structure called the colulus remains, positioned between the anterior lateral pair of spinnerets. Other species of araneomorphs, called cribellate spiders, have a fattened spinning plate, called the cribellum, positioned between the anterior lateral pair of spinnerets.

It is thought that the cribellum and the colulus are homologous structures and both are thought to be evolutionary derivatives of the anterior median pair of spinnerets. The cribellum is also thought to be an ancestral, or plesiomorphic, characteristic among the araneomorph spiders. The cribellum is covered with hundreds to thousands of individual silk spigots. In some cribellate species, the cribellum is divided into two small plates; in others, it is a single continuous plate.

Cribellate spiders also have a specialized comb, called a calamistrum, on the metatarsal segment of the last leg. The calamistrum is used to comb the cribellate silk out of the cribellum. Both cribellate and ecribellate spiders are found in the Haplogynae and in the Entelegynae. Therefore, it is currently thought that the cribellum is a polyphyletic characteristic.

As you can see, spiders are not something exotic and unknown, to be afraid of without good reason. Even the biggest spider in the world is tiny compared to us, and on top of that he doesn't have any good way to hurt us. Whenever you see a spider, you can be sure that he will be the one afraid of you, and he will be the one running away.

Source: EzineArticles
Was this Helpful ?

Rate this Article

Article Tags:

Cribellate Spiders






Silk Production





As a consequence, they are better placed to fight any disease effortlessly. Alternatively, you can give them organic and natural food.As a consequence, they are better placed to fight any disease

By: Simon Liva l Pets > Dogs l December 11, 2012 lViews: 252

The captive parrot population is exploding and so is the neglect and abuse, breeders, Bird Food Manufacturers all seek to keep this trend growing in the name of profits,with no regard for the

By: Ray McLennan l Pets > Birds l November 16, 2012 lViews: 767

The Cardinal is the Kentucky state bird. Many people love watching them in their backyards but are not familiar with the facts about this Northeastern bird. They are stunning against any background

By: Jack l Pets > Birds l October 31, 2012 lViews: 246

Establishing and maintaining good levels of oral health is important for both humans and animals to ensure they can enjoy a quality of life. Each part of the mouth area, from the teeth to the jaws,

By: Edward Swan l Pets > Dogs l October 27, 2012 lViews: 229

There's more to keeping your dog at home than just installing an invisible pet fence and hoping for the best. Take steps to train your dog so he understands and accepts his boundaries.

By: Penny Q Jones l Pets > Dogs l July 06, 2012 lViews: 262

Dogs face many complications and diseases during their lifetime and effects from parasites are one of them. This article entails some significant features that can help you understand the importance

By: Kannoujia Tapas l Pets > Dogs l July 05, 2012 lViews: 262

Ant farms have become a popular accessory on most homes, but in order to ensure the health and safety of its occupants it's extremely important to remember that ants are living beings, not just a

By: Irene Lizarragal Pets > Insects Arachnidsl July 01, 2012 lViews: 181

While it is true that an ant is not likely to climb on the sofa and cuddle with you, or answer when called by its name, thanks to the invention of ant farms they can be considered pets. An ant farm

By: Irene Lizarragal Pets > Insects Arachnidsl July 01, 2012 lViews: 206

Butterflies are many of the most beautiful and interesting creatures on Earth. A butterfly garden is an effective way to see more butterflies and to allow them since many natural butterfly habitats

By: Tom Donnel Pets > Insects Arachnidsl May 22, 2012 lViews: 137

Termites are a homeowners nightmare. They can destroy your home and cause thousands of dollars wort of damage What can you do to protect your home? Read on to find out!

By: Penelope Diazl Pets > Insects Arachnidsl May 07, 2012 lViews: 128

Summer brings warmth, picnics, outdoor fun and stinging bugs such as wasps and yellow jackets. Maybe you have been stung before, and if so, then you know how painful a sting can be. This article

By: Penelope Diazl Pets > Insects Arachnidsl May 07, 2012 lViews: 155

Spring Time It's the time of year where everything is fresh and new. The flowers are blooming, the birds are singing and the bees..

By: Ernest Hensonl Pets > Insects Arachnidsl April 21, 2012 lViews: 135

Discuss this Article

comments powered by Disqus