Black Widow Spider

Location

In the Zoo

Scientific Information

Scientific Name: Latrodectus mactans
Class: Arachnida
Order: Aranae
Family: Theridiidae
Genus: Latrodectus

Size

Male

Female

Height:
Length: 1/8 inch 3/8 inch
Weight:
Maturity: 70-90 days 70-90 days

Lifestyle and Lifespan

Diet: Carnivorous
Activity Timeframe: Nocturnal
Interactivity: Solitary
Sexual Dimorphism: Yes
Gestation: 20 days
Lifespan in the Wild: 1-3 years
Lifespan in Captivity: 4 years

Geographic Range

In the U.S. they're found from Massachusetts to Florida, west to California, Texas, Oklahoma and Kansas;Also found in Canada, Mexico, The West Indies, and South America

Conservation

Status in the Wild:
Threats:

Characteristics

Black Widow spiders are known for their potent venom, which is 15 times as potent as rattlesnake venom.

Species Specifics

Physical Characteristics

As part of the family of comb-footed spiders, they have 6-10 comb-like bristles on the hind tarsi. They use their combs to fling silk strands over any captive that gets caught in the web. The swathed victim is hauled to a rest site on the web, injected with venom and later eaten.

Ecology

Habitat

most common in the South. Found among fallen branches, under stones, in outbuildings and under objects such as furniture.

Distribution

Diet

Black Widows primarily eat insects. However they will also eat diplopods, wood lice, chilopods, and other arachnids.

Ecological Web

Black Widow Spiders help to control insect populations.

Activity and Behavior

Activity Pattern

During the day, the female spider hangs upside down in her web, displaying her red hourglass marking as a warning to potential predators. If prey gets caught in her web, she will wrap it in silk, bite it, and drag it to a retreat inside of her nest to consume it. When eating, she will use her cheliceral teeth to mash up her prey. Then she pours digestive enzymes onto it, and sucks up the resulting food. This whole digestion process takes place outside of the spider's body.

Behavior

When disturbed, black widow spiders will fall out of their web and play dead to avoid predation.

Social Behavior

Black Widow Spiders only exhibit social behavior when searching for mates.

Reproductive Behavior

During the mating season, a mature male spins a small 'sperm web', or web in which he deposits a small amount of semen. He then covers his pedipalps in sperm, abandons his home, and travels in search for females. Once he finds a female, courtship begins. The male begins by vibrating the threads of the female's web, alerting her to his presence. If she is receptive, mating will take place when the male inserts his papal organs into the spermathecal openings of the female. His sperm is released onto her eggs, which are then laid onto a small web and covered with more silk until they are completely surrounded by a cocoon. This cocoon is then guarded or carried by the female until the eggs hatch and spiderlings emerge. A female black widow spider can store the sperm from one mate and use it throughout her lifetime.

Offspring

One egg sac can contain anywhere from 20-900 eggs. While the female spider cares for the egg sac during gestation, parents provide no parental care once the eggs have hatched.

Conservation

Status

Historical

Current Threats

Our Role

How You Can Help

Fascinating Facts

The common name, Black Widow Spider, originates from the females' behavior to sometimes eat the male spider after mating.

Their only known predator is the mud-dauber wasp.

References

McCorkle, Matthew. "Latrodectus mactans." Animal Diversity Web. N.p., n.d. Web. 17 Apr. 2017. .

Kaston, B.J. 1978. How to Know the Spiders. Wm C. Brown Co, Dubuque, Iowa.

Milne, Lorus and Margery.1980. The Audubon Society Field Guide to North American Insects and Spiders. Alfred A. Knopf, New York.

Preston-Mafham, Rod. 1991. The Book of Spiders. Chartwell Books, Edison, NJ.

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