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. Spiders range in size from the tiny Samoan Moss spider, which is 0.011-inch-long, to the massive Goliath bird-eater, a tarantula with a leg span of almost a foot!
Although they are seen as beneficial to our environment, many people do tend to have an inherent fear of spiders, known as Arachnophobia (an extreme and irrational fear of spiders and other arachnids such as scorpions). Thankfully, most species of spiders found in the U.A.E are not considered dangerous and rarely bite. If you do get a spider bite, it often has little effect on most people, Widow spiders and Brown Recluse spiders are the two common venomous types found in the U.A.E.
Basic anatomy of spiders
Spiders are voracious predators, feeding on insects, other spiders and even small mammals and reptiles. Spiders have two, rather than three, body regions. These two regions are the cephalothorax — which is formed by the fusing of the head and thorax and contains the eyes, mouthparts and legs — and the abdomen. The abdomen is unsegmented and contains the genital structures, spiracles and the spinnerets used to spin silk.
Spiders have four pairs of legs. They possess modified appendages called pedipalps located in the front by the mouth. The mouth has several parts. The spider’s jaws, called the chelicerae, are tipped with fangs which are used to hold prey while the spider injects venom. Behind the jaws are the labium and labrum, which direct food into the spider’s mouth.
Most spiders have eight simple eyes located on the front of the cephalothorax, but some have fewer eyes. The arrangement of these eyes is often used to distinguish between various species of spiders.
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. Many spiders spin some type of web; the shape & type of web is often as distinctive as the spider itself. Other spiders are active hunters that move about looking for prey, and do not spin webs.
Life Cycle of a spider
All spiders, from the tiny jumping spider to the huge tarantula, have the same general life cycle. They mature in three stages: Egg, Spiderling, and Adult. Though the details of each stage varies between species, they are all very similar.
The mating ritual also varies and males must approach a female carefully or be mistaken for prey. After mating, many male spiders will die but the female is very independent and will care for her eggs on her own. Despite rumors, majority of female spiders do not eat their mates.
Stage 1 – The Egg & Egg Sac
After mating, female spiders store sperm until they are ready to produce eggs. The mother spider first constructs an egg sac from strong silk that is tough enough to protect offspring from the elements. She then deposits her eggs inside it, fertilizing them as they emerge. A single egg sac may contain just a few eggs, or several hundred, depending on the species.
Spider eggs generally take a few weeks to hatch. In some species, the mother guards the egg sac from predators until the young hatch. Other species will place the sac in a secure location and leave the eggs to their own fate, and other species like the Wolf spider carry the egg sac with them. When they’re ready to hatch, they will bite the sac open and free the spiderlings.
Stage 2 – Spiderlings
Immature spiders, called spiderlings, resemble their parents but are much smaller when they first hatch from the egg sac. They immediately disperse, some by walking and others by a behavior called ballooning (they will climb onto a twig or other projecting object and release threads of silk from their spinnerets, letting the silk catch the wind and carry them away).
The spiderlings will molt repeatedly as they grow larger and are quite vulnerable until the new exoskeleton forms. Most species reach adulthood after five to 10 molts. In some species, the male spiders will be fully mature as they exit the sac. Female spiders are always larger than males, and so take more time to mature.
Stage 3 – Adult
When the spider reaches adulthood, it is ready to mate and begin the life cycle all over again. Most spiders live about two years, but some like the Tarantula are known to live up to 20 years in captivity. Female spiders tend to live longer than male spiders. Many male spiders reach maturity within two years and die after mating.
Are they harmful?
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 of them are actually dangerous to humans. Those include the Black Widow and the Brown Recluse especially in the U.A.E.
A majority of spiders are harmless and serve a critical purpose in our ecosystem – Pest control, as they feed on many household pests such as grasshoppers, aphids, cockroaches, and mosquitoes thus reducing the need for expensive pesticides, this also benefits gardens and agricultural crops. Also, by limiting the population on unwanted pests, spiders can actually decrease the risk of many common diseases. An example being is when spiders consume mosquitoes, they are highly reducing the risk of spreading malaria.
Other benefits of spiders include uses for their venom- scientists are currently researching the benefits of spider venom, which may prevent arthritis. And spider silk – which has proven to be one of the strongest natural materials and is helping inspire mechanical engineering to new heights.
How spiders 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 (like 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.
Despite all of the eyes that’s spiders have, they don’t see very well. A notable exception is the jumping spider, which can see more colors than humans.
Types of spiders found in the U.A.E.
Jumping Spider (SALTICIDAE)
‘Jumping Spider’ is a common name for any of a group of hunting spiders that can leap 10 to 40 times their body length.
Size – Body length generally ranges from 1 to 25 mm
Color – Varies with most being black or gray. Some are brightly colored or possess bright markings.
Habitat – These spiders live outside where they wander about over plant foliage as well as fences, walls, decks and patios in search of insects to prey upon. They rarely enter homes ¬ such invasions are accidental.
Venom Toxicity – They are non-aggressive and few bites are known. Symptoms are minor and localized to the bite site.
Tangle Web Spider (Family – Theridiidae)
The Tangle Web Spiders are also known as Cobweb spiders and Comb-footed spiders. They are a large group of spiders with over 2,200 species in 87 genera.
Size – Body ranges up to three eighths of an inch in length, with a spherical abdomen.
Color – Typically brown or tan with various markings.
Habitat – House spiders will construct their webs in any corner inside or outside. They are commonly found in garages, crawl spaces and basements as these areas are less disturbed and tend to harbor more insects.
Venom Toxicity – They are not known to bite people frequently, nor is their venom known to be dangerous to human beings. When removed from their webs their poor vision renders them helpless.
Domestic House Spider (TEGENARIA DOMESTICA)
Also called Barn Funnel Weaving Spider they are known for their high speed, and can move lightning quick from one corner of the web to another.
Size – Measure up to one inch in length with a leg span up to two inches.
Color – Body color varies from dark orange to brown, beige, or grayish with striped legs.
Habitat – This species prefers to build its webs where a hole or crack exists in which it can locate its funnel retreat. Such webs are usually found in basements, crawl spaces, garages and outdoors in vegetation.
Venom Toxicity – While bites from most spiders are rare, bites from a barn funnel weaver may be rarer still. When they do, bites are said to be both painless and harmless.
Cellar Spiders (FAMILY – PHOLCIDAE)
Commonly known as Daddy Long Legs Spider, surprisingly the web of these spiders isn’t sticky at all. It’s the complicated structure that traps its prey
Size – Up to three quarters of an inch in body length with an extremely thin shape.
Color – Pale whitish or cream.
Habitat – Cellar spiders prefer dark, damp areas, such as crawl spaces, basements and sheds, although they may be common around doorways, in warehouses and sometimes in garages of homes.
Venom Toxicity – Cellar spiders are not proven to be poisonous. Although there is a myth that their venom is one of the deadliest, but because of short fangs they cannot inject this fatal venom into humans. However, there is no research proving this statement to be true.
Black Widow (LATRODECTUS)
Most Black Widow females have a prominent red or orange hourglass marking on their back this marking is to signal danger to predators and attackers.
Size – Adult widows are between one-eighth of an inch to 1.5 inches in length, depending on their gender and species.
Color – The color of widow spiders varies. Most are black with bright red markings, although some are brown with bright orange markings.
Habitat – Black widows produce messy, irregular webs. Webs usually are located near ground level and under a protected ledge such as under lawn furniture or wood piles.
Venom Toxicity – These spiders aren’t aggressive and only bite when they feel threatened but their bite is highly venomous. The venom will cause you to experience pain that’s not limited to the bite location. You could experience difficulty breathing due to paralysis of the diaphragm, headache, nausea, weakness, fever, increase in blood pressure, and muscle spasms.
Brown Recluse Spider (LOXOSCELES RECLUSA)
A distinctive characteristic of brown recluse spiders is the presence of a dark, violin-shaped mark on the dorsum of their light or yellowish-brown cephalothorax.
Size – Body length ranges from 1/4 to 3/4-inch long.
Color – Brown recluse spiders range from a light tan to a dark brown color, with no distinguishing stripes or bands. Their legs have a silky appearance due to fine hairs that grow along the entire length.
Habitat – As their name suggests, they prefer to be “reclusive,” and hide in secluded, dark, undisturbed places in households such as crawl spaces, garages, basements, closets and storage boxes.
Venom Toxicity – A brown recluse spider bite often is not felt when it happens, but it can be serious. The brown recluse bears a potentially deadly hemotoxic venom although most bites are minor with no necrosis. The symptoms most commonly experienced with the bite include nausea, vomiting, fever, rashes, and muscle and joint pain.
Camel Spider (Galeodes Arabs)
The camel spider’s history of misinformation begins with a misidentification. Camel spiders are not even spiders. Like spiders, they are members of the class Arachnida, but while all spiders are arachnids, not all arachnids are spiders. The camel spider is of the order Solifugae, which is Latin for “those who flee from the sun”. Another common name is Wind scorpion/Sun scorpion. They can be identified easily by their enormous chelicerae (fangs), which project from the front of the body as a pair of vertically articulating pincers.
Size – They tend vary a lot in size, with body lengths usually around 2 – 3 inches, though their legs can be several inches long, making them look even larger.
Color – Their bodies are very hairy, and usually reddish-brown.
Habitat – Camel spiders spend the day hiding beneath objects or in shallow burrows dug with their legs and mouth-parts. Since they are nocturnal they usually come out at night to hunt, locating prey with their leg-like mouth-parts, both on the ground and beneath the surface (through ground-level vibrations).
Venom Toxicity – Camel spiders neither have venom glands nor any venom-delivery apparatus such as the fangs of spiders, stings of wasps. Although, their bites can be extremely painful (the size of their fangs are no joke!)