Spiders (orderAraneae) are air-breathing arthropods that have eight legs and chelicerae with fangs that inject venom. They are the largest order of arachnids and rank seventh in total species diversity among all other orders of organisms.[2] Spiders are found worldwide on every continent except for Antarctica, and have become established in nearly every habitat with the exceptions of air and sea colonization. As of November 2015, at least 45,700 spider species, and 113 families have been recorded by taxonomists.[1] However, there has been dissension within the scientific community as to how all these families should be classified, as evidenced by the over 20 different classifications that have been proposed since 1900.[3]
Theridiidae is a large family of spiders, also known as the tangle-web spiders, cobweb spiders and comb-footed spiders. The diverse family includes over 2,200 species in over 100 genera[3] of three-dimensional space-web-builders found throughout the world. Theridiid spiders are entelegyne (have a genital plate in the female) araneomorphecribellate (use sticky capture silk instead of woolly silk) spiders that often build tangle space webs and have a comb of serrated bristles (setae) on the tarsus of the fourth leg.
The spider genus Micrathena contains more than a hundred species, most of them Neotropical woodland orb-weavers.
The species are found in the Americas. Only three species occur in the eastern United States: females of M. gracilis (the Spined Micrathena) have five pairs of conical tubercles / spines on the abdomen, female M. mitrata have two short posterior pairs, and female M. sagittata (the Arrow-shaped Micrathena) have three pairs.
Species with extremely long spines evolved at least eight times in the Micrathena genus and likely function as anti-predator defenses.[1]
Platycryptus undatus occurs in North and Central America. The distribution of this species ranges from the Eastern States and adjacent Canada, to Texas and Wisconsin.[1][page needed]Females of this species are between 10 and 13 mm in body length, and males range from 8.5 to 9.5 mm. Like some other species of jumping spider, this species appears to exhibit curiosity towards humans who come into its visual field (jumping spiders all have very good vision.) It favors vertical surfaces such as fences, walls, etc. and because of its habits it is easily seen. It does not frantically flee humans and may be gently “herded” onto a hand, where it may make a thorough exploration and even jump from finger to finger. These spiders are not at all inclined to bite, but even though they are rather small they can deliver a defensive bite if they are pinched or squeezed.
Eggs are laid and hatch during the summer, and adults and other stages overwinter in their individual silken shelters. Although the shelters are built separately and keep the spiders out of direct contact with each other, Kaston reports that as many as fifty of them may crowd their shelters for hibernation together so tightly that they form a continuous blanket under the loose bark of a standing tree.[2]
Phidippus princeps is a rare species of jumping spider found in Canada and the United States. These jumping spiders’ vision exceeds by a factor of ten that of dragonflies, which have the best vision among insects.
Dermacentor variabilis, also known as the American dog tick or wood tick, is a species of tick that is known to carry bacteria responsible for several diseases in humans, including Rocky Mountain spotted fever and tularemia (Francisella tularensis). It is one of the most well-known hard ticks. Diseases are spread when it sucks blood from the host, which could take several days for the host to experience some symptoms.
Phidippus princeps is a rare species of jumping spider found in Canada and the United States. These jumping spiders’ vision exceeds by a factor of ten that of dragonflies, which have the best vision among insects.
Ant mimicry or myrmecomorphy is mimicry of ants by other organisms. Ants are abundant all over the world, and potential predators that rely on vision to identify their prey, such as birds and wasps, normally avoid them, because they are either unpalatable or aggressive. Some arthropods mimic ants to escape predation (protective mimicry), while others mimic ants anatomically and behaviourally to hunt ants (aggressive mimicry).[1]
To overcome ants’ powerful defences, mimics may imitate ants chemically (Wasmannian mimicry) with ant-like pheromones, visually (as in Batesian mimicry, though the purpose may also be aggressive mimicry), or by copying microstructure for tactile mimicry.[2]
Myriapoda is a subphylum of arthropods containing millipedes, centipedes, and others. The group contains over 16,000 species, most of which are terrestrial.[2]Although their name suggests they have myriad (10,000) legs, myriapods range from having up to 750 legs (the millipede Illacme plenipes)[3]to having fewer than ten legs.
Dermacentor variabilis, also known as the American dog tick or wood tick, is a species of tick that is known to carry bacteria responsible for several diseases in humans, including Rocky Mountain spotted fever and tularemia (Francisella tularensis). It is one of the most well-known hard ticks. Diseases are spread when it sucks blood from the host, which could take several days for the host to experience some symptoms.
A pseudoscorpion, also known as a false scorpion or book scorpion, is an arachnidbelonging to the order Pseudoscorpiones, also known as Pseudoscorpionida or Chelonethida.
Pseudoscorpions are generally beneficial to humans since they prey on clothes moth larvae, carpet beetle larvae, booklice, ants, mites, and small flies. They are tiny and inoffensive, and are rarely seen due to their small size, despite being common in many environments. Pseudoscorpions often carry out phoresy, a form of commensalism in which one organism uses another for the purpose of transport.
Wolf spiders are members of the familyLycosidae, from the Ancient Greek word “λύκος” meaning “wolf”. They are robust and agile hunters with excellent eyesight. They live mostly in solitude and hunt alone, and do not spin webs. Some are opportunistic hunters pouncing upon prey as they find it or even chasing it over short distances. Some will wait for passing prey in or near the mouth of a burrow.
