Spider identification is no easy thing to do particularly if you lack experience and the scientific information that allow one to perform a correct classification. The most common way to perform the identification at a very amateurish level is to actually compare a specimen with a picture or a drawing and see whether there is a match.
The important thing about spider identification is to actually be able to tell the poisonous spiders from the non-poisonous ones. Fortunately, the latter are far more numerous than the former, as poisonous spiders are spread only in certain globe areas, and sometimes they have warning features that sets them apart.
In North America for instance, poisonous spider identification is a thumb rule for anyone living close to such creatures; there are not too many species of the kind, hence, once you learn how to set them apart you can relax and feel a lot safer. House species are the first to require proper spider identification since they are the first we come into contact with, and, on certain occasions, it is pretty difficulty to tell them apart. This is the case with the house spider, the giant house spider and the hobo spider; they all live indoors, but only the latter is a real threat to humans, since its bite can cause necrosis.
In order to avoid direct contact with spiders indoors, you can use special sticky traps that will drastically lower the risk of being bitten by a venomous species. For such cases spider identification is not necessary; but we cannot say the same thing about the widow spiders that require the immediate use of an anti-venom. Therefore, spider identification can be crucial when you need to be able to apply the right treatment without any further delay. Spiders that live outdoors are more difficult to identify due to the large number of species both harmful and venomous.
All in all, spider identification serves not only to the scientist but to the average person who either takes a great interest in the various spider species or who’d like to avoid risky exposures and eventual bites. Protection measures need to be taken when working outside in areas where poisonous species live; thus, make sure you wear special gloves particularly if you spend some time around debris piles and wood piles for instance.
Such crawl spaces are the favorite habitat of widow spiders for instance, and their threat should by no means be ignored or taken lightly.
Spiders – What Are They?
They sometimes frighten us by their appearance. Their very thin, long legs and hairy body resembles like that of a monster. These terrific animals are the spiders. The spiders belong to the largest phylum of the animal kingdom Arthropoda and class Arachnida. The spiders have eight legs with well developed chelicerae transformed into fangs for injecting venom into the body of the victim. They breathe air. The spiders together constitute the largest population of the arachnids and rank seventh in the number of species present all over the world as compared to other organisms. They are cosmopolitan in distribution but absent in Antarctica. They do not colonize in sea and air. By 2008 the taxonomists have recorded 40,000 species and 109 families of spiders but confusion about this classification is still prevailing that how this record has been made and whether all the species are correctly classified or not.
The body plan of the spiders differs from that of other arthropods in having divided into two tagmata, the cephalothorax and abdomen and the two are joined by a small structure the pedicel. They lack antennae like insects. A primitive group of spiders called the Mesothelae had a well developed nervous system as compared to all other arthropods consisting of a large ganglion fused in one mass in the cephalothorax. Spiders lack extensor muscles in their limbs and use hydraulic pressure for extending their limbs.
The abdomen possesses well developed and modified appendages termed as spinnerets using for the production of silk from six different types of silk glands embedded within the abdomen. The spider webs differ widely in shape, size and mount of the silk thread used for its construction. In 2008 a vegetarian species of spiders was discovered but rest of the species are predators preying on insects, spiders and few larger species also predate upon birds and lizards. Spiders adapt various astonishing techniques for capturing their prey like they trap their prey in the sticky web, also show mimicry. Most of the species capture prey with the help of sensing vibrations but spiders of genus Portia have well developed sense of vision. The gut of the spiders is very narrow so they are unable to take the solid food. They liquidize the food with the help of digestive enzymes and grind the food with pedipalps as they lack true jaws.
The male spiders use fascinating courtship rituals in order to avoid being eaten by the female spiders. Males have a very short life span and after few matings they die. The females lay eggs in silken cases and each case houses hundreds of eggs. The females of few species also show parental care towards the eggs. Social organization has been noticed in few species like that of widow spiders which make a huge web enclosing about 50.000 individuals. Most species have a life span of about 2 years but the tarantulas and the mygalomorphs live up to 25 years in captivity.
Spider venom is harmful to human beings and the research is going on to make use of the spider venom in medicines and in non-polluting pesticides. Spider silk is a good source of strength, lightness and is much more superior to that of the synthetic materials. They are also a symbol of terror and cruelty in the mythology. They are chelicerates and their body like that of other arthropods has been divided into segments bearing jointed appendages covered by cuticle and is made up of chitin and other proteins. Head is made up of a large number of segments that fuse together in the embryo. They are coelomates and the coelom is reduced to a small area around the excretory and the reproductive organs. The position of the coelom is mainly taken by the haemocoel, a cavity that runs along the length of whole body and blood flows through it. The heart is in the form of a tube present in the upper part of the body consisting of few ostia that act as non-return valves. The spiders have open circulatory systems. Many spiders have book-lungs and it bears a respiratory pigment haemocyanin for oxygen transport. Respiration may be carried out by book-lungs or tracheal systems. The tracheae in spiders are efficient organs of water conservation and maintain the metabolic rate better.
The spiders excrete their waste product in the form of a nitrogenous waste termed as uric acid which comes out of the body in the form a solid. The excretory organs are the Malpighian tubules that help to pass uric acid through anus. The general plan of the central nervous system in the spiders consists of brain formed by the fusion of ganglia inside the cephalothorax and the mouth and the nerve cords that arise from the ganglia. Most spiders bear four pairs of eyes in front area of the cephalothorax and also bear pigment cups called ocelli that help in the detection of light. The other eyes are responsible for the mosaic vision as they are compound eyes. There are a large number of bristles or setae present all over the body which act as touch and taste receptors. The spiders lack well developed muscles in their limbs so they move with the help of hydraulic pressure. If the cephalothorax of a spider is damaged it is unable to move its legs. Spiders can generate pressure of more than eight times for extending their legs and the jumping spiders can jump 50 times their length with the help of the hydraulic pressure.
The spider silk is produced by the silk glands present in the abdomen and it resembles with that of the insect silk. It is basically a protein that is usually soft but hardens on exposure to air. It resembles nylon, collagen in its tensile strength. Spiders reproduce sexually and the fertilization is internal but indirect. The females are oviparous and lay about 3,000 eggs in silken egg sacs which are kept at a particular humidity level. The females of some species die after egg laying but most species protect their eggs by attaching them to their nests or by other means. The baby spiders pass their larval stages within the egg sacs ad hatch out as small, sexually immature, tender spiderlings.
Three classes of pigments have been identified in the spiders and they include, ommochromes, bilins and guanine. Many spiders use camouflage as their measure of defense. Some species of spiders also show social behavior. Scientists believe that spiders have evolved 100 million years ago. The bites of the spiders are responsible for a number of symptoms like headache, redness, pain, itching, shortness of breath, muscular cramps etc. Some spiders are also a source of delicacy for the people of some countries. The tarantulas are cooked and eaten by some people.
Spiders are beneficial as well as dangerous but they are a very important part of our eco-system.
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