Showing posts with label Spider. Show all posts
Showing posts with label Spider. Show all posts

Tuesday, October 2, 2012

Wolf Spiders

Wolf spiders
(Lycosidae)


photo via http://bit.ly/Q6ZEAW

Wolf spiders are members of the family Lycosidae, from the Ancient Greek word "λύκος" meaning "wolf". They are robust and agile hunters with excellent eyesight. They live mostly solitary lives and hunt alone. 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.
Wolf spiders resemble Nursery web spiders (family Pisauridae), but wolf spiders carry their egg sacs by attaching them to their spinnerets (Pisauridae carry their egg sacs with their chelicerae and pedipalps). Two of the Wolf spider's eight eyes are large and prominent, which distinguishes them from the Nursery web spiders whose eyes are all of approximately equal size. (Wikipedia)

Appearance: These are usually large spiders. Wolf Spiders can range from 3-30 mm in body length. Female wolf spiders are often bigger than males of the same species.


photo via http://bit.ly/OBvibU 


Like all spiders they have two body sections: the cephalothorax in front and an abdomen behind. The abdomen contains the digestive and reproductive systems, and on the underside of it are the glands where silk is produced. The structures that produce the silk are called spinnerets.

Wolf spiders have eight legs, all attached to the cephalothorax. On the front of the cephalothorax are the mouth, the fangs, the eyes, and two small "mini-legs" called pedipalps. These are used to grab prey, and in mating, and are much bigger in male spiders than in females. They have eight eyes in three rows. The front row has four small eyes, the middle row has two much larger eyes, and the back two eyes are medium sized and off to the sides. These spiders have strong fangs and and venom glands to quickly kill their prey.

Wolf spiders are colored in camouflage colors of brown, orange, black, and grey. Sometimes they are all one color, but usually they have some stripes or blotches.

Wolf spiders are found all around the world, and about 2,300 species are known. There are about 50 species of wolf spiders in Michigan.

Wolf spiders live in all kinds of habitats, anywhere there are insects to eat. They seem to be most common in open habitats like grasslands, and are often found in farm fields and meadows. Most species stay on the ground, but a few climb up onto trees and other plants when hunting. Some wolf spiders hunt along the shores of ponds and marshes, and may even dive into the water to capture prey.

These spiders can be found in the following types of habitat: temperate; tropical; terrestrial.
Terrestrial Biomes: taiga; desert or dune; chaparral; forest; rainforest; scrub forest; mountains.
Aquatic Biomes: lakes and ponds.
Wetlands: marsh; swamp.

Wolf spiders hatch from eggs, and the hatchlings look more or less like grown-up spiders, though sometimes their colors change as they age. In many species, the hatchlings ride on their mother's body for some time before going off on their own. To grow, spiders must shed their exoskeleton, which they do many times during their lives. Unlike insects, some spider species keep growing after they become adults, and continue to molt as they grow even larger.

After mating, female wolf spiders lay a batch of eggs (usually several dozen or more), which they wrap in silk. If she gets enough food, a single female may produce several clutches of eggs in a year. They are seasonal breeders (sexual; oviparous). Female wolf spiders wrap their eggs in a round ball of silk, and keep them close. Wandering species carry their egg sack under their abdomen as they move around. Tunnel-building species keep their eggsacks in their tunnels, and bring them up to warm in the sun during the day (the warm temperature helps their eggs develop faster).

Parental investment: female parental care.
Male wolf spiders probably don't live more than a year, but females of some species can live for several years.

Behavior: many wolf spider species hunt at night, but some are active during the day. 
They are solitary animals, they hunt alone and only come together to mate.

Some species wander, hiding during the day and roaming at night to find food. Some patrol a regular territory, returning to the same place to rest. Others dig tunnels, or use tunnels made by other animals. A few build little walls or turrets around their tunnels, and then sit inside the wall looking out for passing prey or predators.

Key behaviors: diurnal; nocturnal; crepuscular; motile; nomadic; sedentary; solitary; territorial.
How do they communicate with each other?
Wold spiders use their vision more than most other spider groups. Males often signal to females by waving their pedipalps in certain patterns. Wolf spiders are also very sensitive to vibrations in the ground, and use scent and taste as well.

Wolf spiders eat insects and other invertebrates, and really large females might eat very small vertebrates, like amphibians and reptiles, if they find them. They sometimes attack insects that are larger than they are.

Different species of wolf spider have different ways of finding prey. Some build tunnels and ambush prey that come near their hiding place. Others wander on the ground, looking for small animals to eat. When they find a target, they jump on them and grab and quickly bite. Often they roll over onto their backs and hold the prey in a "basket" made by their legs before they bite.



photo via http://bit.ly/QeXC4r
Primary Diet: carnivore (eats terrestrial vertebrates, eats non-insect arthropods).
What eats them and how do they avoid being eaten?
Known predators: other spiders, wasps, ants, praying mantids, birds, small reptiles, toads and other amphibians, and shrews.
Wandering wolf spiders rely on speed and camouflage to escape predators. They have good vision and are very sensitive to vibrations in the ground that help them detect predators. Some species hide in tunnels in the ground. Wolf spiders will bite to defend themselves if necessary.

Wolf spiders can give you a painful bite if you handle them carelessly, but it the bite usually doesn't do much damage unless the person bitten is allergic to the venom.

Wolf spiders are often common in agricultural areas, and can be very helpful in reducing populations of insect pests.

No wolf spiders are known to be endangered. (Michigan University - BioKids)



Edited, Revised and Condensed by:  Scott Glaze    August 26, 2012

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Wednesday, January 4, 2012

Spiders

SPIDERS

For the most part, spiders are harmless and generally beneficial. Spiders are seldom aggressive and bite only when threatened or injured. Few spiders ever bite people, and the venom of most species is harmless to humans. However, bites from the brown recluse (also known as the Recluse or Fiddle-Back) and the black widow can be quite dangerous. Please keep in mind, the more you understand any pest, the easier it will be to control.
Spiders are the largest group of arachnids. There are more than 35,000 named species worldwide, including about 3,000 in North America, but probably most spider species are still awaiting identification. These predators live almost everywhere: on the ground, under rocks, inside and underneath playground equipment, among grasses, on plants, in tree branches, in underground caves and even on the water – depending on the species. Spiders frequently stray into dwellings and other structures, or may be accidentally introduced on firewood, laundry that has been hung out to dry, or on flowers, etc. Spiders will also sneak into our homes in boxes, clothing or furniture, through window areas and any crack or crevice that allows them entry. Web-building spiders often construct webs near lights because insect prey may be attracted at night by the lights and by air currents.
Spiders are easily recognized by the 4 pairs of seven segmented legs and (like all arachnids) have a cephalothorax and abdomen. But unlike scorpions, mites and daddy-long-legs, the cephalothorax and abdomen of the spider are separated by a visible waist or pedicel. The top of the cephalothorax is protected by a shield-like covering called the carapace.
Most species have 8 simple eyes, although some have less and a few species have none. Often the number and arrangement of eyes are important in identifying the different families. Below the eyes are 2 small jaws (or chelicerae) that end in fangs. Venom is produced in glands and empties through a duct in the fangs. This venom is used to paralyze or kill prey. Then the spider crushes the victim by rubbing the chelicerae against each other and against the enlarged bases of the pedipalps, located before the first legs. There are usually 6 finger-like silk glands (spinnerets) located beneath the abdomen, just in front of the anus.
Not all spiders spin webs. Some live in burrows, which they line with silk, while others have no retreat at all. All young spiders and some adult males release long silken strands, which they use like a parachute to ride on wind currents to other areas - a process is called ‘ballooning’.
Most spiders lay their eggs in silken egg sacs that are placed in the web, attached to leaves or twigs, or carried around by the spider until the eggs hatch. Spiderlings (as the young are sometimes called) resemble adults and are often cannibalistic. All spiders are predators and most feed on insects, although a few large species prey on small vertebrate animals.
This is the Brown Recluse Spider
Brown Recluse on a quarter
Black Widow Spider

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