Spiders can be readily distinguished from insects as they 8 legs instead of 6, and have 2 body segments of 3, the head and thorax are fused into one unit which contains eyes, mouth parts and legs.
The abdomen section is soft and houses the reproductive organs, the silk glands and spinnerets and the respiratory openings which are visible on the under surface. This large surface area achieves the transference of oxygen into the blood.
There are usually 4 pairs of eyes, each a simple lens. The arrangement of these eyes in a pattern is constant for each species and aids in identification. The fine hairs and setae on various parts of the body are said to be sensitive to taste, touch and vibration.
Most spiders are nocturnal and hence are seldom seen during the day unless disturbed.
Some spiders depend on a web to snare their pray and seldom move far from the web, and hide in a crevice, curled leaf or appear camouflaged as twigs. Hunting spiders, many of which are ground dwelling spiders are less dependent on webs and move around in the dark hours in search of food.
Males seek out females at mating time, and after mating the male is often consumed by the female as a high protein meal to assist in the egg production process. The eggs are usually deposited in a silken sac, with the spider-lings hatching inside the sac and moult once they emerge. By successive moults they become adults and usually expect to live for 1-3 years.
Whether the spider traps prey in a web or hunts to capture it, the victim is injected with venom through the fangs, this immobilises it, the body is then squeezed and the erupting liquid is sucked in through he small mouth behind the fangs at the base of the palps. Most species can survive for months without food.