arachnid | arthropod | Britannica.com arthropod Howard T. Ricketts Arachnid (class Arachnida), any member of the arthropod group that includes spider s, daddy longlegs , scorpion s, and (in the subclass Acari ) the mite s and tick s, as well as lesser-known subgroups. Only a few species are of economic importance—for example, the mites and ticks, which transmit diseases to humans, other animals, and plants. Garden spider (Araneus diadematus). General features Body and appendages Arachnids range in size from tiny mites that measure 0.08 mm (0.003 inch) to the enormous scorpion Hadogenes troglodytes of Africa, which may be 21 cm (8 inches) or more in length. In appearance, they vary from short-legged, round-bodied mites and pincer-equipped scorpions with curled tails to delicate, long-legged daddy longlegs and robust , hairy tarantula s. Representative members of subclass Acari (mites and ticks). Encyclopædia Britannica, Inc.

Like all arthropods, arachnids have segmented bodies, tough exoskeleton s, and jointed appendages. Most are predatory. Arachnids lack jaws and, with only a few exceptions, inject digestive fluids into their prey before sucking its liquefied remains into their mouths. Except among daddy longlegs and the mites and ticks, in which the entire body forms a single region, the arachnid body is divided into two distinct regions: the cephalothorax , or prosoma, and the abdomen , or opisthosoma. The sternites (ventral plates) of the lower surface of the body show more variation than do the tergites (dorsal plates). The arachnids have simple (as opposed to compound) eyes. Diversity of arachnids. Encyclopædia Britannica, Inc. The cephalothorax is covered dorsally with a rigid cover (the carapace) and has six pairs of appendages, the first of which are the chelicerae , the only appendages that are in front of the mouth. In many forms they are chelate, or pincerlike, and are used to hold and crush prey.

Among spiders the basal segment of the chelicerae contains venom sacs, and the second segment, the fang, injects venom. The pedipalps , or palps, which in arachnids function as an organ of touch, constitute the second pair of appendages. In spiders and daddy longlegs the pedipalps are elongated leglike structures, whereas in scorpions they are large chelate, prehensile organs. Among spiders the pedipalps are highly modified as secondary sexual organs. The basal segment is sometimes modified for crushing or cutting food. The remaining four pairs of appendages are walking legs, though the first of these pairs serves as tactile organs among the tailless whip scorpion s (order Amblypygi); it is the second pair that functions as such among the daddy longlegs. Among the spiderlike ricinuleids (order Ricinulei), special copulatory organs are located on the third pair of legs. Some mites, particularly immature individuals, have only two or three pairs of legs.

Damon diadema, a species of tailless whip scorpion, in a cave near the … Thomas Brown Scientists Ponder Menopause in Killer Whales The numbers and predaceous habits of arachnids make them important to humans. Free-living mites play an important role in the conversion of leaf mold to humus. Many mites are parasitic, and many ticks are intermediate hosts for organisms that cause serious diseases. Though all spiders possess poison that can be utilized for subduing prey, only a few have a poison sufficiently powerful to affect humans. A bite of the black widow spider (Latrodectus mactans) may result in discomfort or serious illness , whereas that of the brown recluse spider (Loxosceles reclusa) may result in a severe local reaction, including tissue death. The sting of some scorpions may cause a severe reaction and even death. Natural history Reproduction and life cycle In most cases the male does not transfer spermatozoa directly to the female but rather initiates courtship rituals in which the female is induced to accept the gelatinous sperm capsule ( spermatophore ). During mating the sperm are transferred to a sac ( spermatheca ) within the female reproductive system.

The eggs are fertilized as they are laid. Mating in sunspiders is more active, occurring at dusk or during the night. During courting the male seizes the female, lays her on her side, massages her undersurface, opens her genital orifice, and forces a mass of sperm into her spermatheca. Reproductive behaviour in mites is highly variable; sperm usually are produced in a spermatophore and transferred to the female either by the chelicerae or, in ricinuleids, by the third pair of legs of the male. Connect with Britannica Spider Facts - The Body of a Spider KidZone Spider Facts The Body of a Spider Spiders have two body segments. The front segment is called the Cephalothorax. The spider’s eyes, mouth fangs, stomach, brain and the glands that make the poison are on this part of the body. The legs are connected to this part, as well. Most spiders have eight eyes, but some have less. Spiders also have these tiny little leg-ish things called ‘pedipalps’ that are beside the fangs. They help to hold prey while the spider bites it. Can you identify all the body parts on this Wolf Spider?

The second part of the body is called the Abdomen. The back end of the abdomen is where the spinnerets, the silk producing glands, are. The spider’s body has an oil on it to keep the spider from sticking to it’s own web. Spider’s legs are covered with many hairs. The hairs pick up vibrations and smells from the air. At the end of the legs are, at least, two small claws. Spiders have 48 knees. Yup, count them…eight legs with six joints on each. Spiders do not have a skeleton inside their bodies. They have a hard outer shell called an ‘exoskeleton’. Because it is hard, it can’t grow with the spider. So young spiders need to molt, or shed their exoskeleton. The spider must climb out of the old shell through the cephalothorax. You can imagine how hard it must be to pull all those legs out! They are pretty helpless at this point. Once they are out they must stretch themselves out before the new exoskeleton hardens. This gives them a bit of growing room. As adults, they stop growing and do not need to molt. Male spiders are usually smaller than females.

Common spiders in and around homes : University of Minnesota Extension Common spiders in and around homes Jeffrey Hahn, Phil Pellitteri, Laura Jesse and Donald Lewis On this page Related information Spiders are as familiar and well known to most people as they are disliked. The unpopular reputation of spiders is undeserved. Myths about spiders and the negative consequences of biting by a very, very small number of species overshadow the ecological benefits spiders provide. All spiders are beneficial predators that feed on insects, spiders, and other arthropods, and thus help reduce pest populations in and around homes, landscapes, gardens, and crops. Characteristics Spiders are related to insects but are distinctly different. Spiders and insects are both arthropods; that is, animals with an exoskeleton (their skeletons are on the outside of their bodies) and jointed legs. Differences between spiders and insects are described in the accompanying chart. Spiders are closely related to mites, ticks, and scorpions and are collectively known as arachnids.

Comparison between spiders and insects Simple, usually eight (rarely six) Compound, two Four (sometimes two or none) Antennae Chelicerae (fangs) Mandibles (jaws) All spiders produce silk throughout their lifetime. Silk is produced as a liquid in specialized structures called spinnerets located at the tip of the abdomen. Silk hardens as it is drawn from the spinnerets and has contact with the air. Spider silk is used to build webs and other types of snares that capture prey, and to make egg cases, draglines, shelters, and retreats. Silk produced by spiderlings (young spiders) enables them to be transported by air currents and wind in a process called ballooning. Spiders are predators feeding mainly on living insects, mites, and other small arthropods. Spiders are considered beneficial because of the large number of insects they prey on, including a number of pest species. All spiders have venom that is injected through the hollow fangs (chelicerae) into the living prey to immobilize the prey and begin the digestion process.

Spiders feed by liquefying the prey with digestive fluids that are injected or regurgitated into the prey and then sucking in the digested food. Spider behavior Spiders can be divided into two groups depending on how they capture their prey. Hunting spiders do not construct webs to capture food. Instead, they rely on quickness and relatively good eyesight to chase and capture prey. Active hunters (sometimes known as wandering spiders) actively search for and chase their prey. Passive hunters lie in wait and seize prey as it approaches. Hunting spiders live outdoors, but may wander into homes accidentally, particularly in the fall, but they do not survive well and usually do not reproduce indoors. Web-building spiders construct webs in calm, undisturbed places to capture their food. They live in or near their web and wait for food to come to them. They generally have poor eyesight and rely on sensing vibrations in their web to detect prey. Spider bites Spiders very rarely bite people and far less than is generally assumed. Most spiders are harmless to people and are incapable of biting, even when coaxed.

Most people and even medical doctors overstate “potential spider bite” diagnosis based on ambiguous symptoms such as redness, swelling, cramps, severe pain, or even necrotic lesions that can be caused by other factors including other diseases or medical conditions and bacterial skin infections. For more information on spider bites and dangerous spiders, see Potentially dangerous spiders . Common spiders in and around homes (Note: Sizes given under spider descriptions represent the length of the body not including the legs.) Hunting spiders Hunting spiders are outdoor spiders that may wander indoors as accidental invaders. Listed below are the most common hunting spiders that may be found indoors. Wolf spiders (figure 1) are moderate to large-sized spiders (¼- to 1-inch long) with dark brown and slightly hairy bodies. Wolf spiders are found on the ground or under stones in a wide variety of habitats, such as woodlands, grassy meadows, beaches, landscapes, gardens, and fields. Some even live underground. They commonly hunt during the day or at night when it is warm. Wolf spiders are alarming because of their large size and rapid movements. They are not aggressive and, according to The Golden Guide to Spiders, they make good pets.

Sac spiders (figure 2) are normally found on foliage or on the ground. They are small to medium-sized spiders (1/5- to 2/5-inch long) and are usually yellowish or light-colored. Sac spiders hunt at night, feeding chiefly on small insects, and hide during the day in a silken tube or sac, from which they take their name. They do not construct webs. Outdoors, they usually roll up leaves into a tube, or may construct a retreat under stones. Inside buildings, sac spiders are found in retreats in a variety of places, including high up on walls near ceilings. Figure 1. Wolf spider Figure 2. Sac spider Fishing spiders (figure 3) are typically seen near ponds, swamps, or slow-moving streams, but some may be found at considerable distances from water. Fishing spiders are the largest spiders in the Upper Midwest (1-inch long). With legs spread out, some fishing spiders cover as much as 4 inches. They are generally dark-colored, usually brownish or grayish, with white markings. Fishing spiders can “skate” across water and can dive underneath to capture prey.

In addition to insects, fishing spiders also can catch tadpoles, small fish, and other small vertebrate animals. Sowbug spider (figure 4), also known as the woodlouse hunter or the dysderid spider, is an introduced species that is now common and widely distributed in the United States. This medium-sized spider has distinctive coloration: the cephalothorax is purplish-brown, the abdomen is grayish-white, and the legs are orange. Unlike the majority of spiders, the dysderid spider has only 6 eyes. The chelicerae (fangs) are quite large and project forward. Dysderid spiders wander at night in search of food and are ground-dwellers commonly found under rocks and debris. As the name implies, their preferred prey are sowbugs and pillbugs, though a variety of prey may be taken. Figure 3. Fishing spider Figure 4. Sowbug spider Jeffrey Hahn Jumping spiders (figure 5) are compact, medium-sized spiders that get their name from their ability to leap on their prey, often jumping many times their own body length.

They are active during the day and are often found on windows, ceilings, walls, and other areas exposed to sunlight. Jumping spiders are compact, small to medium-sized (about ¼- to ½-inch long) and dark-colored with white markings. Some can be brightly colored, including some with iridescent mouthparts. These spiders move quickly in a jerky, irregular gait and can run sideways and backward. The two middle eyes of jumping spiders are particularly large and jumping spiders have the best vision of spiders, seeing objects up to eight inches away. Parson spider (figure 6), one of the gnaphosid spiders, is a medium-sized spider (½-inch long) with a brownish body and gray abdomen with a white band running down over half the length of its abdomen. Parson spiders actively hunt at night and chase their prey. During the day, they are usually found outdoors under stones or loose bark in silken retreats. Indoors, they hide under objects or in cracks or crevices. Figure 5. Jumping spider Figure 6.

Parson spider Jeffrey Hahn Crab spiders (figure 7) are small to medium-sized spiders (1/10- to 2/5-inch long) ranging in color from yellow or red to brown or gray. The first four legs are longer than the back four and are held out to the sides giving a crab-like appearance. They can walk forward, sideways, or backward. Crab spiders are passive hunters—they wait motionless and ambush insects that pass by closely. Outdoors, crab spiders are often found on flowers but are also seen on stems or leaves. They are rarely found indoors. Figure 7. Crab spider Web-building spiders Some species of web-building spiders can survive and reproduce well indoors and outdoors. Cobweb spiders (figure 8) are members of a large group also called the comb-footed spiders and are very common both outdoors and indoors. They are small to medium-sized spiders (about 1/8- to 3/8-inch long) and have a rounded, globular abdomen, small cephalothorax, and brownish or grayish color. They are sedentary and construct the familiar, irregular, tangled webs for which the group is named.

Webs are built in undisturbed, out-of-the-way places such as wood and stone piles and in quiet areas of buildings, such as basements. A common type of combfooted spider found indoors is the American house spider, also called the common house spider (figure 9). It is grayish to brownish with chevron-like markings on its abdomen and a body length of over ¼ inch. It builds a loose tangle of webs (“cob webs”) in secluded and undisturbed areas of the house such as basements and crawl spaces. Cellar spiders (figure 10), including the long-bodied cellar spiders, are common in dark secluded places such as crawlspaces, basements, and cellars (as the name implies). Like the cobweb spiders, the cellar spiders build a loose, irregular web in corners near the ceiling or floor. Cellar spiders are 1/3 to ¼ inch long, pale gray to light tan in color and have long delicate legs (resembling the daddy-longlegs). Figure 9. American house spider University of Nebraska Figure 10. Cellar spider University of Nebraska Orb weaver spiders are common spiders outdoors in gardens, fields, and landscapes. They are rarely found indoors.

The orb weaver spiders make the familiar “typical” spider web of concentric circles and radiating lines. They range in size from small to large (1/8- to 1-inch long) and are found in a variety of colors, some being brightly colored. Orb spiders have large, swollen-looking abdomens, including some that are oddly shaped. Despite their large size and bright coloration, orb weaver spiders are not dangerous. Figure 11. Black and yellow argiope University of Nebraska Figure 12. Barn spider Jeffrey Hahn Common orb weaver spiders include the black and yellow argiope (are-JI-o-pee) spider, the barn spider, and the marbled orb weaver spider. The black and yellow argiope (figure 11), also known as the garden spider, is familiar to many. It is large (up to 1-inch long) and brightly colored black and yellow. The barn spider (figure 12) is large (4/5-inch long) and yellow and brown in color. The barn spider is the model for Charlotte in E.B. White's famous book, Charlotte's Web.

The marbled orb weaver spider (figure 13) is a striking spider that attracts attention because of its typical bright orange color, though specimens vary from orange to beige to pale yellow and white. Figure 13. Marbled orb weaver spider Phil Pellitteri Figure 14. Barn funnel weaver Phil Pellitteri Funnel weaver spiders produce a flat, horizontal web with a small funnel-like retreat off to one side. Webs are commonly built on the ground, around steps, window wells, foundations, and low shrubs. Funnel weaver spiders are generally brownish or grayish with stripes near the head and a pattern on the abdomen. They have long spinnerets and are moderate-sized (¾-inch long). Figure 15. Grass spider Jeffrey Hahn A common member of the funnel-web spiders is the barn funnel weaver (figure 14). Barn funnel weavers have a pair of dark stripes behind the head and may build webs in corners and closets indoors. Other common funnel weavers are called grass spiders. Grass spiders (figure 15), like the name suggests, build their horizontal webs in the short grass of lawns.

They have three light colored and two dark colored stripes behind the head. Management of spiders in and around homes Control of spiders is best achieved with an integrated pest management (IPM) approach that includes multiple tactics for prevention, exclusion, and population reduction. Since the type of spider will determine the necessary control actions, start by identifying the spider involved. Spiders are not harmful. Tolerance for spiders and simple capture and removal are recommended whenever possible. However, dangerous spiders such as the black widow and brown recluse, both very rare in the upper Midwest, require immediate attention and control. Eradication of all spiders from a home is difficult and unnecessary. Properties located in areas favorable to spiders, such as by rivers, lakes, or fields, are more likely to have large numbers of spiders. Spiders also will be more numerous in areas with a large supply of insects that serve as a food source for spiders. Each situation is unique, but the following guidelines describe the integrated techniques that can be used to control spiders. Indoors Regular housecleaning is very important in the control of spiders indoors. Large, persistent spider populations indoors indicate the presence of a significant insect population that serves as their food. Capture and discard or remove individual spiders that have wandered inside.

Remove papers, boxes, bags, and other clutter to minimize favorable sites for spiders. Remove webbing with a broom or vacuum, and destroy any egg sacs and spiders that are found. Look especially around windows, in corners, and in relatively quiet places. Sticky traps such as small glue boards or cockroach traps can be used to monitor for presence and abundance of spiders. In limited circumstances sticky traps also may provide some level of control. Place traps along walls, under furniture and appliances, and in other undisturbed locations. Eliminate insects that serve as a food supply, especially when large numbers exist. Check particularly in and under webs to see what insects have been captured. Osage orange fruits, also called hedgeballs or hedge apples, are sold in stores and alleged to repel spiders. They are not effective and their use is not recommended. You can supplement your sanitation efforts with an insecticide treatment. Lightly apply insecticide to cracks, gaps, and other places where spiders may hide. General treatments on surfaces and fogs are not effective. Most insecticides labeled for ants and cockroaches are also labeled for spiders. These products are commonly found in ready-to-use aerosol and liquid formulations.

CAUTION: Read all label directions carefully before buying insecticides and again before using them. Outdoors Use the following techniques if accidental invasion by wandering spiders from outdoors is a frequent problem or to reduce an unacceptable number of spiders around your home and prevent spiders from getting inside. Otherwise, spider control in the lawn, landscape, and garden is not recommended because spiders are beneficial and an important component of the ecosystem. Remove piles of bricks, firewood, and other debris that may serve as suitable homes for spiders or move them further from your home. Keep grassy or weedy areas near buildings cut short. Trim back shrubs and other plants that directly contact your home. Periodically remove webs with a broom, vacuum, or a hard spray of water. Remove and destroy any egg sacs or spiders that are found. Check to be sure screens fit tightly. Replace any screens that fit poorly or are damaged. Reduce outside lighting to minimize attraction of insect prey that can encourage spiders. Yellow lights are less attractive to insects than mercury or sodium vapor lights. When possible, place security lights on a pole shining toward a door rather than on the building above the door. This will reduce attracting insects that spiders feed on to the building.

Caulk or seal cracks or gaps around the foundation, doors, and ground level windows. As a last resort, lightly apply a broad-spectrum insecticide labeled for the exterior of buildings on the outside of your home to reduce invasion by wandering spiders. Spray under siding, in cracks and crevices, and other places where spiders may hide. General treatments on the siding or other surfaces are not effective. Read and follow all pesticide label directions. Related information Spider Identification – Types of Spiders | Wolfspider.org Spider Identification – Types of Spiders October 7, 2013 | By sobelarry | 5 Replies More Spider identification and knowing the types of spiders is not easy because there are many different types of spiders. In fact, there are thousands upon thousands different types of spiders in the world. They range from the very small up to those who are large enough to be the size of dinner plates. So how do we do spider identification and how many types of spiders are out there? Before we go on to spider identification and discussing the types of spiders, we must first define what are spiders in the first place. Types of Spiders – What are Spiders? Spiders are arthropods which breathe air.

They have eight legs and inject venom through their chelicerae. They are of the order Araneae and are the largest in the order of arachnids. In the world, they are seventh in the rank of total diversity of the species among all other organism groups. They have 109 families and 43,678 spider species as of 2008, and the number is still growing. Spiders are everywhere in the world except in the continent of Antartica and has been existing for over 300 million years. Are Spiders Insects? Spiders are not insects. They differ from other arthropods in their body structure. They do not have antennae like insects do. Their bodies are also fused into two segments, the abdomen and the cephalothorax. More so, they use hydraulic pressure to move their legs, since they do not have extensor muscles in their legs like insects do. It is important to be able to differentiate spiders from insects in order to be able to know how to do spider identification.

Once you know that what you are faced with is a spider and not an insect, it is easier to talk about how to identify them and discuss the common types of spiders in existence. Types of Spiders – How are Spiders Classified and Grouped? Classifying spiders into types is not an easy task, because there are a lot of possible means of classifying or grouping them. They can be classified according to the type of web they have or whether they spin one or not, or they can also be classified in more technical terms based on taxonomy. Types of Spiders According to Taxonomy Spiders have two sub-orders, Opisthothelae which has two infra-orders, the Araneomorphae and the Mygalomorphae, and Mesothelae. Of them, it is the Araneomorphae which has the most number of living species at 40,000. Has 4 pairs which is located under the middle of the abdomen. May have 1, 2 or 3 pairs under the rear of the abdomen. May have 1, 2 or 3 pairs under the rear of the abdomen.

How the Fangs Strike Like pincers, which is from the side going to the center. Common Examples -Orb-web spiders-Wolf spiders-Jumping spiders The above table only tackles the differences which is readily visible to the eye to make spider identification easier. Spider Identification – Common House Spiders in America Below is a table of the common house spiders found in the continent of America, particularly, North America to make spider identification of the different types of spiders easier for the common observer: Name American House Spider Venomous non-fatal bite -Males are smaller and with a darker coloration.-Have an elongated abdomen which is colored dirty white with some dark spots and sometimes with a black triangular shape in the center.-Body is colored yellow-brown. -Usually found in dark places like closets, barns, garage, crawl spaces, in between furnitures and angles of windowpanes.-Very common all over the United States. -They can play dead when threatened.-They have very poor vision. Black Widow Toxic bite which is potentially fatal. Seek medical attention as soon as bitten. -Females are shiny and black. They also have a red hourglass shape on their abdomen-Males are often brown or dark gray.

If they have an hourglass shape, it is usually color white or yellow, which makes spider identification a bit confusing. -Usually found in dark places like closets, barns, garage, inside shoes, crawl spaces, woodpiles, in between furnitures and angles of windowpanes.-Very common all over the United States. -Both males and females have strong venoms, but females have venom which is thrice as deadly compared to males.-They have the reputation of being one of the most deadly among the types of spiders. Brown Recluse Toxic bite which is potentially fatal. Seek medical attention as soon as bitten. -Can be light colored to dark brown with a violin shape on their abdomen which is darker than the rest of their bodies.-Best spider identification feature is presence of 6 eyes which is arranged in pairs all over the head. Usually found behind pictures, in woodpiles, barns, cardboard boxes, and dressers.-They are fairly common in the middle of the United States, less common in the coastal states, and do not live in the northernmost states bordering Canada. -They are very reclusive and do not attack humans unless provoked.

Daddy Longlegs Non-toxic bite -Can range from pale yellow, to light brown and gray coloration.-They have a fused body appearing as one with no distinct head or abdomen.-Has very long thin legs which makes them easy to distinguish among other the types of spiders. -Usually found in sheltered spaces like under the sink, closets, windows, ceilings, in between furnitures, and garage.-Very common all over the United States. -Are not real spiders but they do look like one so they are part of this spider identification chart of the types of spiders.-They have no silk glands, and have a fused body.-No proven study that they have venom although it is a common belief that they do. Domestic House Spider Non-toxic bite -Can be dark orange to brown in color and have a pale colored mark on the breastplate.-The legs have dark bands which makes them look striped.-Has a V-shaped mark across the abdomen in a lengthwise arrangement.-The body is distinctively funnel-shaped. -Usually found in dark spaces and crevices like attics, basements, and closets.-Very common all over the United States.

-They are usually confused with their relative the Hobo spider which is dangerous.-They can keep the population of more harmful spiders down because they are more competitive for food. Hobo Spider Venomous non-fatal bite -Can be dark orange to brown in color and have a pale colored mark on the breastplate.-The legs have dark bands which makes them look striped.-Has a V-shaped mark across the abdomen in a lengthwise arrangement.-The body is distinctively funnel-shaped. -It looks like the Domestic House Spider but the Hobo has a light colored stripe that runs down the middle of its sternum, making this a characteristic mark for Hobo spider identification. -Usually found in rarely disturbed places like the cupboards, behind furnitures, garage, basements, and attics.-Fairly common in the west coast, particularly the southern part. It is absent in the east coast though. -They are actually very common in Europe and were only just imported in the United States around the 1930s.

Hobo Spiders – Facts and Fallacies about the Hobo Spider December 28th, 2013 Being one of the most feared amongst the types of spiders, Hobo Spiders indeed has become known for [...] Grass Spider – Get to Know the Grass Spider December 18th, 2013 The Grass Spider is a group of common spiders which resides on grassy areas and catches their prey b [...] December 16th, 2013 The Brown Recluse Spider is one of the most misunderstood creatures amongst the ranks of spiders. Hu [...] Black Widow – Black Widow Spiders Facts and Fallacies December 13th, 2013 The Black Widow is one of the most feared of the types of spiders all over the world and for a good [...] Banana Spiders – Guide on the Different Types of Banana Spiders December 12th, 2013 Banana Spiders have gathered a bad reputation over the years as being deadly killers. All over the w [...] Common Spiders of Maryland - Maryland's Wild Acres Maryland's Wild Acres Creating a Wild Backyard - Common Spiders of Maryland Main_Content Spiders are some of the hardest working wildlife in Maryland.

Many people are fearful of spiders and often overlook the critical role they play controlling insect pests. Knowing how to distinguish some of the different types of spiders and understanding the important functions that they serve in our environment can often lead to a greater appreciation of their beneficial qualities. This online guide is not an inclusive list of spiders found in Maryland, but it contains many commonly encountered spiders. There are over 40,700 species of spiders worldwide and hundreds of species in Maryland. What it Takes to be a Spider Spiders are classified as Arachnids. Other types of Arachnids include mites, ticks and harvestmen (aka “Daddy long-legs"). Spiders are different from other Arachnids because their body is divided into two major sections which are separated by a pedicel or narrow connection. The front part of the spider’s body is called the cephalothorax while the back is called the abdomen. Attached to the abdomen are finger-like appendages known as spinnerets. These structures are the silk-spinning organs and are often used for spider identification. Super Silk All spiders spin silk, but not all spiders use the silk for their webs.

Some spiders use the silk to protect their eggs, store their food or build a temporary home. Spider silk is strong and elastic which allows them to catch fast flying food or secure their young to their backs. On a per weight basis, spider silk is stronger than steel! Venom and Bites Many of the spiders in Maryland possess venom, but the black widow is the only native Maryland spider that is dangerous to people. All other venomous Maryland spiders either have too little venom to affect people or their venom is specially adapted for their prey. Brown recluse spiders are not native to Maryland, but on very rare instances they can stow away on packages from the Midwest and the Southwest where the Brown recluses are more common. Only 10% of Brown recluse bites develop into tissue necrosis (cell death) around the bite area. Recently, many researchers are realizing that many previously diagnosed brown recluse bites were actually methicillin-resistant Staphylococcus aureus, or MRSA infections. Treatment for MRSA infections and spider bites are similar.

Brown recluses can be identified by several characteristics such as: 1) six eyes arranged in pairs, 2) a dark violin-shape on the cephalothorax (head), 3) uniformly light-colored legs (without stripes or bands), 4) 3/8 inch length body and 5) no spines on the legs. Brown recluses are often misidentified. The University of California has an excellent page on brown recluse identification and misidentification here . Spider bites are actually quite uncommon, and most spiders will only bite humans in self defense. While spiders have fangs, they are usually too small to leave visible puncture wounds. Many times, spider bites will result in pain, redness, itching and swelling that lasts a couple of days. Spiders rarely bite more than once, so multiple bites are usually caused by insects such as fleas, bedbugs, chiggers, ticks, mites and biting flies. Although black widow and brown recluse spider bites are rare, care must be taken to properly identify and treat the wound. Healthy adults may only experience mild symptoms but children, the elderly and those with compromised immune systems should be extra cautious.

Guide to Common Spider Groups Cellar spiders Family: Pholcidae Cellar spiders tend to have extremely long, skinny legs with small bodies. Cellar spiders make stringy webs, often in the corner of rooms, to catch flies and gnats. When food is scarce, Cellar spiders will abandon their webs and tap on another spider’s web to mimic captured prey. When the other spider comes out to investigate its “catch”, the cellar spider will eat the unsuspecting spider. Cellar spiders are commonly found in homes, but they typically stay in one place and don't bother people. Cellar spiders are not known to bite people. Cobweb spiders Black widows (Latrodectus) Black widows are distinctive spiders. The females are shiny black with a red hourglass on the bottom of her abdomen while males have a more vibrant pattern on their abdomen consisting of many red and white spots. Male black widow spiders are rarely encountered and are not known to bite humans. Black widow bites feel like a minor pinprick, but dull pains will soon develop in the area of the bite. The affected area will generally begin to cramp and other symptoms such as sweating, nausea and vomiting may occur.

Black widow spiders are cobweb spiders that spend most of their time in their webs. Black widows tend to make their webs in undisturbed, uncluttered areas on porches and in sheds. To discourage them from inhabiting an area, then knock down their webs with a broom or a high pressure hose. In some areas, you can vacuum up spiders and their eggs, but be sure to immediately place the vacuum cleaner bag in a plastic bag, seal tightly, and discard in a container outdoors as this prevents captured spiders from escaping into the home. Common house spider (Parasteatoda tepidariorum) True to their name, common house spiders are frequently found in human dwellings. Like Black widows and other cobweb spiders, common house spiders build messy, tangle webs usually around windows. Common house spiders can have variable appearances. Females are generally mottled gray or tan while the males tend to have a more reddish appearance. Crab spiders Family: Thomisidae Crab spiders are not active hunters and use the art of camouflage to snag their prey. Crab spiders are named after their crab-like appearance with large front legs that are often held out to the sides of their body.

These spiders come in all different colors, many of which are specially adapted to their hunting grounds. For example, the goldenrod crab spider is a bright yellow color which allows it to easily blend in with the yellow petals of goldenrods. Crab spiders are viewed as beneficial to people as they tend to eat many insect pests found in gardens and flower beds. Interestingly enough, scientists believe that the venom of many crab spiders is more potent than most spiders. This allows the crab spiders to quickly subdue prey such as bees. Crab spiders are not known to bite humans, though. Funnel weavers/Grass spiders Family: Agelenidae Funnel weaving spiders look very similar to Wolf spiders, but they make webs and have three rows of eyes. True to their name, funnel weavers make funnel-like webs along the ground in which the spider hides in. When a prey species crosses the web and vibrates it, the spider will jump out and grab its new meal. Because of this feeding strategy, funnel weaving spiders are designed to be incredibly quick and most rarely leave their webs. Jumping spiders Family: Salticidae Jumping spiders are truly the Casanovas of the Arachnid world.

Not only are many jumping spiders brightly colored, but the males put on elaborate songs and dances for the ladies. Jumping spiders are named for their movements which consist of jumps or short, rapid runs. Jumping spiders tend to have a large pair of eyes mounted on the front of a relatively flat-face. The other three pairs of eyes are relatively small in comparison. Jumping spiders are adept hunters. Their keen eyesight paired with speed allows them to catch prey with amazing accuracy. Jumping spiders do not build webs, but they do use their silk as a tether when they go to pounce on prey. If their aim is off, they can use their silk thread to return to their original location. Jumping spiders are often found in and around human structures, especially in barns and sheds. Nursery web and Fishing spiders Family: Pisauridae Nursery web spider (Pisaurina spp.) Nursery web spiders are large, hairy spiders that usually have a dark stripe running through their eyes down the back of them. Nursery web spiders consist of several species in the genus Pisaurina. Nursery web spiders will carry their egg sacs in their jaws and then will build a “nursery tent” shortly before they hatch.

The female will guard the nursery web until the young spiders reach their first molt. Most adults get up to an inch in size. Nursery web spiders can commonly be found in and around homes, but they pose little to no threat to humans. Fishing spiders (Dolomedes spp.) Fishing spiders look very similar to wolf spiders in regards to size and coloration. However, fishing spiders tend to have much longer legs, relative to the rest of their bodies and have alternating brown/black bands on their legs. Many species of fishing spiders live near water and often catch small fish, aquatic insects and tadpoles. One exception is the dark fishing spider (Dolomedes tenebrosus) which lives in wooded areas and occasionally seeks refuge in basements. Orb-weavers Family: Araneidae Orb-weavers strongly resemble cobweb spiders. However, true to their name, orb weavers create webs that are organized and have a circular grid. Orb-weavers need structures such as weeds, fences, trees, walls or other upright structures to build their webs. Orb weavers are considered beneficial to humans as they eat many pest insects including the invasive Brown-marmorated stinkbug!

Black and yellow garden spider (Argiope aurantia) True to its name, the black and yellow garden spider is often seen n and around gardens. These spiders are orb-weavers, meaning that they spin their webs in a circle or an orb. These webs can be up to 2 feet across, while the spiders themselves can have a leg span of nearly 2.5 inches! Females are much larger than the males, and often times, these spiders will decorate their web with a zig-zag of white silk. Black and yellow garden spiders prefer to build their webs in sunny areas and often will rebuild their webs every day. Micrathena spiders Spiders in the genus Micrathena tend to have spiky abdomens and are notorious for weaving webs at face level along trails. If you have ever run into a spider’s web in late summer while hiking in Maryland, then there is a good chance it was a Micrathena web! Micrathena spiders feed mostly on small flies, gnats and mosquitoes. Males do not build webs, rather they let the ladies do all the work. When a male is ready to mate, he will weave a ‘mating thread’ into her web before mating with her.

Many times, females will kill the males shortly after mating. Spined Micrathena spiders (Micrathena gracilis) are the most common Micrathena in Maryland. Marbled orb weavers (Araneus marmoreus) Marbled orb weavers are some of the showiest spiders found in our area. The abdomens of these spiders become yellow with black marbled patterns as they mature, and sometimes around Halloween, the yellow turns to an orange color. Most marbled orb weavers hide in rolled up leaves until an unsuspecting prey gets captured in their webs. Wolf spiders Family: Lycosidae Wolf spiders are agile hunters that live alone and actively hunt prey instead of tending to webs. Wolf spiders have exceptional eyesight and often hunt at night. Their eyes are reflective, so they can often be seen at night by shining a flashlight over them. Wolf spiders tend to be brownish-gray and can grow just over an inch in length. Wolf spiders are often confused with the Brown recluse, but they lack the unmistakable violin-shaped marking behind the head. Female wolf spiders are very maternal and will carry their eggs in a sac on their back.

When the eggs hatch, the female will carry the hatchlings on her back until they are large enough to hunt on their own. Wolf spiders are not aggressive, and like most spiders, will only bite when they feel threatened. Invite Wildlife to Your Backyard! For Additional Information, Contact: Mark David | How many eyes does a spider have? mdavid.com.au How many eyes does a spider have? There have been lots of movies with giant spiders in them. One of the things that makes them look so creepy is having so many eyes. But is that just something from the imagination of Hollywood? This young St Andrew’s Cross Spider (Argiope species) doesn’t need great eyesight. Its orb web does the main job at catching prey Most spiders, but definitely not all spiders, have eight eyes, and the way those eyes are arranged can often help scientists work out what kind of spider it is. Of course, that’s assuming they’re prepared to get close enough. Spiders usually have some eyes on top of their head* and some more in front. With so many eyes, it’s a bit surprising that they usually don’t have good eyesight. Instead, they probably just see light and dark shapes moving around.

When they’re hunting they make up for that bad eyesight with an excellent ability to sense vibration and taste. Let’s start by talking about a spider which lots of us are familiar with. This close-up picture of a Huntsman spider shows two rows of eyes, with four eyes in each row. When we move in a bit closer we can see that the surfaces of those eyes appear to be shiny and smooth. These kinds of eyes are called simple eyes because each eye contains just one lens. Here’s one of those eyes shown at even greater magnification. I’m grateful to the Huntsman for sitting so still for me while I took this photo. Compare the smooth surface of that simple eye in the photos above with the surface of a compound eye, shown in the extreme closeup in this next image. This picture shows just a very tiny part of the surface of a Dragonfly’s eye magnified so much that you can see that it’s covered with tiny facets. Each one of those little facets is another lens. Spiders do not have these types of eyes. That Huntsman spider had a lot of hair, which made it a bit tricky counting its eyes. So it would be nice to find a spider that wasn’t so hairy.

This flower spider (Diaea variabilis) will do. So let’s move in a lot closer. This should do it. At this magnification it’s easy to count eight eyes. I was talking before about how most spiders, despite having up to eight eyes, usually have poor eyesight. One exception to that bad-eyesight rule is the group of jumping spiders, which see really well. They have very big eyes on the front of their head*. The pictures of a typical jumping spider shown here makes this point pretty clear. When you look at that pictures you’ll notice two things: It has a row of big black eyes It’s watching me take its photo Those two things are connected. Jumping spiders see a lot of stuff with those big eyes. They use them to investigate whatever they see moving. That can make them difficult to photograph because they keep jumping onto the camera lens. Just to prove that one wasn’t unusual, here’s another type of jumping spider. You can see those big eyes along the front again. From this angle you can see that there are more than just those big four big eyes. Moving in closer it’s now possible to see that, once again, there are eight eyes.

Well, it’s possible, but not so easy … … so I made it easy. In this picture I’ve traced the outlines of that spider and coloured the eyes in red. Now you can see more clearly what I was talking about. Here’s one of my favourite spiders. It’s called Deinopis and I think they’re cool because their faces look almost human! In fact, that face has earned these spiders the name of Ogre-faced Spiders. But does it have only two eyes like a human? Nope! It turns out that these guys have eight eyes too. So then, what’s the full story? Exactly how many eyes do spiders have? When you start looking around you find that some have six eyes. And there are other kinds of spiders with four, two or even no eyes! But most spiders have eight eyes. *I talked about eyes on the front of spiders’ heads. Well, maybe I shouldn’t have said that. Unlike insects, which have a head, a thorax (the bit in the middle) and abdomen (the bit at the end), a spider’s head and thorax are combined into one big section called the ‘cephalothorax’.

So I should have talked about those eyes being on the front of its cephalothorax instead. Now don’t you just love that kind of accuracy. EXPLORIT SCIENCE CENTER: Science Facts and perhaps the page " More About Spiders " SPIDER FACTS Introduction Biologists classify animals and plants according to characteristics that they have in common. Organisms that move from place to place of their own accord and that do not manufacture their food from raw materials in their environment are classified as animals. Organisms that cannot move from place to place of their own accord (but can be moved by forces of nature or by animals) and that can manufacture their own food from raw materials in their environment, are called plants. Within the huge group called animals are many that have no backbones. These are called invertebrates. The invertebrates include mostly small animals. Some live in water and some on land. Some move around by wriggling, some walk, and some fly. One major group or phylum of invertebrates is called the Arthropoda. Biologists include insects and spiders in this group. 1. Spiders are not insects. Why not? Because they have some characteristics that are different from insects.

Amongst the vast numbers of invertebrate animals in the Phylum Arthopoda, more than a million different kinds have bodies with three main parts--head, thorax, and abdomen. The head has eyes, antennae and mouthparts. The thorax has three pairs of legs. The entire body is protected by a tough outer covering called an exoskeleton. Animals that share these characteristics are called insects. The group to which they belong is called the Insecta. Another, smaller, group of invertebrate animals has only two main body parts. The body consists of a combined head and thorax called the cephalothorax, and the abdomen. The cephalothorax has the eyes, mouthparts (no antennae) and four pairs of legs. Animals that share these characteristics include ticks, mites, scorpions and spiders. The group is called the Arachnida. 2. Are all of the Arachnida alike? No. Within the Arachnida, spiders are classified into a special group called the Araneae that separates the spiders from the ticks, mites, and scorpions.

A distinguishing characteristic of spiders (Araneae) is that they have a very slender waist or pedicel separating the cephalothorax from the abdomen. The cephalothorax is covered by a tough carapace. Spiders are believed to have existed for more than 300 million years. 3. What body parts do all spiders have? A spider's body consists of: a) a cephalothorax with eyes, mouthparts - a pair of jaws and a pair of pedipalps, and four pairs of jointed legs and b) an abdomen connected to the cephalothorax by a narrow pedicel. The entire body is encased by a tough protective exoskeleton and much of the body has sensory hairs growing from the skin. 4. Do spiders have claws? Yes. They have claws at the end of each leg. Spiders' legs are segmented and each leg has 7 segments: a coxa (attached to the cephalothorax), trochanter, femur, patella, tibia, metatarsus, and finally a tarsus which may end in two or three small claws. Web-building spiders typically have three claws on the end of each leg.

The middle claw and a small tuft of hairs help the spider cling on to its web. 5. Do spiders have muscles? Yes. The four pairs of legs are powered by muscles. And, muscles attached to the spider's gut and to the inside wall of the cephalothorax can contract to create a strong sucking action during feeding. 6. Do spiders have blood? Yes. Spiders have an open, blood circulatory system. This sort of blood system has a heart, arteries and veins but no capillaries. The heart is tubular with a single cavity and with valves to maintain the flow of blood always in the same direction. The spider's blood is pale blue due to the presence of haemocyanin dissolved in the lymph. There are some blood cells but they are for wound-healing and defense against infection - there are no special blood cells like the human red cells which carry oxygen around the body. 7. How do spiders breathe? Spiders have lungs. There are two sorts of lungs neither of which is like a human lung. Some spiders have book lungs. A book lung has a stack of soft plates called lamellae. Oxygen in the air passing between the lamellae diffuses through the tissue into the blood.

Other spiders have tracheae which are breathing tubes held open by rings of chitin. The tracheae open to the outside and the opening is called a spiracle. There appears to be no active, muscular breathing mechanism. Air seems to pass in and out of the book lung or the tracheae in a passive manner. 8. Can spiders bite? Yes. Below the eyes on head end of a spider's cephalothorax are two small jaws (chelicerae) that end in fangs. Venom (poison) is produced in glands behind the jaws and empties along ducts in the fangs to paralyze or kill prey. Relatively few spiders bite people because they are not able to pierce the skin with their fangs. The majority of those spiders that can bite people have venom that is harmless to people. Two notable exceptions in the United States are the Brown Recluse, and the Black Widow. 9. Do all poisonous spider bites have the same effect? No. When dealing with the effect of spider venom on humans there are two types. Some spider venom is neurotoxic; that is, it affects the human nervous system beyond the site of the bite. The black widow venom is neurotoxic.

A principal component of this venom is a-latrotoxin. A black widow bite causes rigidity , cramp, and paralysis of the sympathetic systems. Occasionally it causes death. Other spider venom is necrotic and causes damage to the tissues surrounding the site of the bite. The recluse spiders have necrotic venom. The damage usually results in skin blisters, ulcers and blackening of the local tissues. 10. Are all animals affected by spider bites? No, probably not. Of course, insects are seriously affected by the venom since insects are the staple of most spiders' diet. Spiders inject venom into the body of a captured insect to paralyze it. Cats are very susceptible to black widow venom as are horses but dogs are relatively resistant, and sheep and rabbits are apparently immune. 11. How many spiders have poisonous venom that affects humans? While there are only a few spiders in the United States that are really dangerous to humans, there are significant numbers around the world. The black widow and recluse spiders have very toxic venom that can be life threatening to humans. Some wolf spiders in South America, and some running spiders (family Chiracanthium) worldwide have venom that causes painful symptoms in humans.

Pigeon spiders of West Africa give very painful bites. In Australia there are between 50 and 100 venomous species at least two of which can be life threatening to humans, the red-back and the Sydney funnel-spider. 12. How do spiders catch their prey (food)? There are four main methods that spiders use to capture prey. a) Sedentary spiders living in silk-lined burrows leap out to capture passing insects. b) Some, normally active spiders, lie in ambush on plants, tree bark, on the ground or under stones. c) Some spiders, like hunters, go in search of their prey. d) Many spiders spin webs to entrap their prey. 13. What - and how - do spiders eat? All spiders are carnivorous, Most spiders eat insects but a few of the larger species are big enough to prey on small vertebrate animals like mice or small birds. Most spiders' jaws work from side to side. They have toothed edges used in breaking up the prey during feeding. Digestion starts before any of the prey (the food) is swallowed.

Some spiders inject digestive enzymes into the prey before they start breaking it up; others secrete digestive fluids as they are breaking the food up with their jaws. The partially digested food is sucked into the spider's alimentary canal (gut). 14. How many eyes do spiders have? Most spiders have eight simple eyes. [Insects on the other hand have large, compound eyes.] The two main eyes of a spider each have a simple lens, and a retina which is made up of light sensitive cells whose surfaces point toward he light as it enters the eye. These main eyes have a small field of vision with high resolution. They are especially well developed in jumping spiders. A spider's secondary eyes also have a lens but the light sensitive cells of these eyes point away from the light as do the similar cells in a human eye. The secondary eyes detect shadows and the difference between light and dark. 15. What are spider webs made of? Spider webs are made of continuous strands of spider silk produced from about six silk glands beneath the abdomen. A web-spinning spider first constructs a web framework attached to parts of plants or other firm supports. This framework has threads radiating out from the center.

Next, the spider will work from the edge of the web toward the center laying down a spiral of sticky threads. A good description of how a spider constructs a web can be found in The Book of Spiders by Paul Hillyard. 16. What is spider silk made of? Spider silk is a protein that is formed as a liquid by silk glands and squeezed out of spinnerets like toothpaste from a tube. The liquid thread hardens as it leaves the spinneret and some types of such thread become stronger than a steel thread of the same diameter. Most of the silk threads in a spider web are multiple strands of fine silk lying alongside each other. Spiders produce several types of silk from different types of spinning glands. One type of silk formed by all spiders is the type used for wrapping prey. Another type of silk is used to make the egg sac, and yet other is a sticky type often used as part of a web. 17. Do all spiders spin webs? No. However, spiders that do not spin webs do produce silk. Some live in burrows which they line with the silk from their silk glands. Young spiders ride the wind on long silk threads in a process that we call ballooning.

Most spiders put their eggs into silk sacs. 18. Where do spiders live? Spiders are found all over the world in all sorts of habitats from the sea shore to the dessert - on the ground, under rocks, on plants, in trees, in caves, on water. Each type of spider tends to be found in a habitat to which it has become specifically adapted. 19. How do spiders travel? All spiders, of course, travel around their immediate territory on foot. But small and young spiders can travel for many miles being carried through the air by a breeze. This method of travel is called ballooning. It depends upon the spider being in the right position so that the breeze draws out a line of silk from one of the spinnerets on its abdomen. The long, delicate strand of silk is carried high up into the air with the tiny spider suspended at its end. 20. How many different types of spiders are there? There are now about 35,000 named species of spiders worldwide. This includes about 3,000 species in North America. Biologists and naturalists believe that there are many more species of spiders still to be identified and named.

The 35,000 species of spiders in the Order Araneae are grouped into three sub-orders and seventy different families. In the following examples, except for the so-called tarantulas, we have given only family names and have not indicated to which sub-orders they belong. SPIDER TYPES - a selection 21. Tarantulas (Order Araneae, Family Theraphosidae) These are the largest spiders. The name tarantula really belongs to members of the family Lycosidae but in the USA the Theraphosidae are commonly called tarantulas. Their hairy bodies may be 10 cm long with a leg span of nearly 15 cm. Some South American types have venom that is dangerous to humans but the bite of a North American tarantula is no more dangerous than a wasp or bee sting. Tarantulas typically hide during the day in burrows or dark holes. They may line their burrow with silk. They do not spin webs. Their jaws - unlike other spiders - move up and down and they feed on large insects and even small vertebrates such as mice or birds.

The male tarantula lives only a few years but in captivity a female can live for 35 years. 22. Wolf Spiders (Order Araneae, Family Lycosidae) These spiders live and hunt on the ground amongst dead leaves and debris, on sand dunes, or on the muddy surface of marshes. Most do not spin webs but dig burrows or have no home at all. Female wolf spiders carry their egg sacs around with them until the eggs hatch and then carry the spiderlings on their backs until they disperse. Burrowing members of this family are true tarantulas and belong to the genus Lycos. These large wolf spiders live in burrows with trapdoors and are known to bite humans causing tissue necrosis. 23. Trap-door spiders (Order Araneae, Family Ctenizidae) These quite large spiders have spines on their jaws that they use to dig burrows in the ground. They seal the opening with a hinged lid or trapdoor. Some types have a delicate silken trapdoor while others have a thick, tightly fitting lid made of earth and debris. The spiders wait in their burrows until they sense that a suitable prey is close by.

Then they rush out, seize the victim, inject it with venom and drag it into the burrow. 24. Jumping Spiders (Order Araneae, Family Salticidae) This is the world's largest family of spiders. These small to medium sized spiders (usually well under 10mm long) are called jumping spiders because of the spectacular leaps they make as they pounce on their prey. Their leaps can be up to forty times their body length. They have quite large eyes and better than usual spider eyesight and are excellent hunters. As a jumping spider leaps onto its victim silk streams from its spinnerets and serves as a life-line. Some species of jumping spiders are beautifully colored and patterned, sometimes with irridescent hairs. 25. Nursery Web Spiders (Order Araneae, Family Pisauridae) These spiders spin webs not to catch prey but to care for their young. The web is constructed in low plants or shrubs and the female guards the eggs until they hatch and the tiny, perfectly formed spiderlings emerge and disperse. Some members of this family are called fishing spiders.

These spiders can run over the surface of quiet water and can creep below the surface for as long as 30 minutes to catch a small fish or tadpole. 26. Spitting Spiders (Order Araneae, Family Scytotidae) A spitting spider has special glands in its cephalothorax which produce a sticky substance that is squirted onto its prey. As the spider spits out the gum it turns it head from side to side so that the gum falls in a zigzag pattern and holds down the prey so that the spider can give it a paralyzing bite. Once the prey is dead the spider frees it from its sticky bonds, pours digestive juices over it and starts feeding. 27. Crab Spiders (Order Araneae, Family Thomisidae) The Crab spiders are a large family distributed worldwide. These spiders have a sideways scuttling movement similar to that of crabs. A few members of this family habitually rest on flower heads waiting for unwary insects. These spiders tend to be colored to match the flowers that they visit. Most members of the family though are drab colored and rest on vegetation or on the ground. 28.

Orb Web Spiders (Order Araneae, Family Araneidae) The members of this large family vary greatly in size, shape and color. Orb weavers spin webs with non-sticky radiating strands and spiraling sticky threads. The spider often rests near the center of the web waiting for an insect to become caught . But others like the barn spider wait above the web during the day connected to it by a silk signal line and is thus alerted when an unsuspecting insect disturbs the web. The Garden spider eats its old web and spins a new one each day. The Bola spider does not spin a web. Instead it dangles a silk thread with a sticky globule on the end and swings it to capture a passing moth. 29. Funnel-Web Spiders (Order Araneae, Family Agelenidae) These small to medium sized spiders - under 20mm long - spin sheet webs of non-sticky silk with a funnel extending from the center to one edge and a barrier web over the top to catch insects. The spider sits in the funnel.

When a flying insect hits the barrier and falls onto the sheet web the spider rushes out of the funnel, bites the victim to paralyze it, and drags it into the funnel to feed on it. An unusual member of this family is the water spider (Argyroneta). This spider feeds on small water organisms and spends its life below the surface of lakes and ponds living in a bubble of air held in the water by a silken diving bell or thimble-like structure. A good description of how the spider constructs this astonishing structure is given in Spiders of the World by Ron & Ken Preston-Mafham. 30. Daddy Long-legs (Order Opiliones, Family Phalangiidae) Sometimes thought to be spiders, Daddy Long-legs are not spiders. They are not included in the Order Araneae. They have a very superficial similarity to spiders in that they have 4 pairs of legs but their legs are stilt-like and are kept bent with the body close to the ground. The daddy long-legs eats insects and other invertebrates as well as the tender gills of fungi and soft decaying matter.

References: Spiders of the World, Rod&Ken Preston-Mafham, 1984 Blandford Press Ltd. National Audubon Society Field Guide to North American Insects & Spiders, 1980 Alfred A. Knopf, New York. The Book of the Spider, Paul Hillyard, 1994 Avon Books BioKIDS - Kids' Inquiry of Diverse Species, Thomisidae: INFORMATION Skip directly to main content . Kids' Inquiry of Diverse Species Local animals in this group: Additional information: Thomisidae What do they look like? Crab Spiders usually have short, wide, flat bodies. The first two pairs of legs are larger than the back legs, and are usually held open so that the spider can easily grab its prey. They usually walk sideways or backwards, and use just their back legs. This is where they get their name. All crab spiders have eight eyes, and the eyes on the edges of their cephalothorax are often raised up on bumps, so they can see in all directions. These spiders have small fangs compared to other spiders, but their venom acts quickly to paralyze their prey.

In some species males and females are different colors, and males are often much smaller than females. Crab spiders usually are colored to match their habitat. Some species can slowly (over a period of days) change color to match the color of the flowers they are hiding on. Other Physical Features female larger Where do they live? There are over 2,000 species of crab spiders and they are found all over the world. In North America there are over 200 species. Biogeographic Regions Which species of spiders have only six legs? - Quora Quora Matan Shelomi , Entomologist All arachnids have eight legs. If it has six legs, it's not a spider. However, some spiders have adapted their two front legs for purposes other than walking, and in these cases the front legs may be so diminished in size as to be inconspicuous. Other spiders, such as the Nursery Web Spider, have a habit of holding their first two leg pairs very close together, giving the appearance of only six legs. Matan Shelomi , Entomologist As Rebecca said, all spiders have eight legs. Well, at least all spiders START OUT with eight legs.

But it’s not uncommon for spiders to lose a leg, or two legs, or more, over the course of their lives. This can happen from a predator encounter, from a leg getting caught somehow, or even during a molt. If conditions are too dry while the spider is molting, it may not be able to pull one or more of its legs out of the old exoskeleton, so it ends up with some legs missing. Many spiders can get along quite well even with fewer than eight legs. And if the spider is not yet mature, it is possible that the next time it molts, a missing leg will have regrown. The new leg is usually smaller than the others, but has full function! Pretty amazing!

Question: Arachnids usually have how many legs?
Answer: Eight