Friday, April 29, 2011

Lycosa Furcillata: The Wolf Spider

Lycosa Furcillata

Figure 1. (above and below) The Lycosa Furcillata

I. Introduction
Kingdom: Animalia
Phylum: Arthropoda
Class: Arachnida
Order: Araneae
Superfamily: Lycosoidea
Family: Lycosidae
Genus: Lycosa
Species: furcillata

Lycosa furcillata is one of the many species of wolf spiders that we commonly find in our homes. There are over 2,000 species of spiders that carry the common name ‘wolf spider’. Wolf spiders belong to the family Lycosidae. In Ancient Greek, the word "λύκος" is translated as “wolf” and these spiders earn their name because they actively hunt down their prey. They always look like they’re on the prowl because their bodies remain low to the ground at all times. But don’t be fooled, even though they carry the name wolf, they are still very shy and scurry away at the slightest disturbance.
The Lycosa furcillata can be commonly found in gardens, homes, in leaf litter, areas of tall grass, or under stones and logs (as can be seen in figure 2).

Figure 2. A lycosae hiding in the brush.

II. Anatomy
Lycosa furcillata ranges from half an inch to two inches in length. They tend to be brown and grayish in color. They have eight eyes in all which are arranged in three rows; four on the bottom and two in the middle and on top. They are very hairy and they use their hairs to sense the environment. The wolf spider has a cephalothorax and a large abdomen.

Figure 3. Simple anatomy of a wolf spider

III. Form and Function
The wolf spider, unlike most spiders, actively hunts its prey. They have excellent vision (for a spider) and hunt well in the night and in the day. Their gray and drab coloring helps them to camouflage. Not only do they have good eyesight but they also have a good sense of touch from the multiple small hairs that cover their body, their setae. Lycosa furcillata are opportunistic feeders and feed on animals ranging cockroaches, mealworms, crickets, and small lizards.

Figure 4. A wolf spider feeding

The spider either ambushes or hunts its prey. They’ve been known to chase down their prey for short distances. They grab their prey with their front legs and bite down with their vicious jaws, or chelicerae. Their chelicerae crush the victim and venom is injected. The venom reduces the innards of the prey into a gooey liquid. The spider sucks the liquid and leaves a shriveled husk. There are cases in which wolf spiders commit “superfluous killing” where they spider kills multiple times and abandons the bodies. It is believed that this behavior is a sort of population control on the prey species.
The Lycosa furcillata is also prey to a vast range of predators; owls, coyotes, lizards, and many predatory insects. There is a type of wasp whose sting paralyzes the wolf spider. The wasp then lays its eggs into the wolf spider’s body where the baby wasps will hatch and eat the spider alive.
Reproduction can be a tricky business for males. Mating season generally occurs during spring and summer. The male will approach the female tentatively and engage her in an intricate courtship dance. If the male doesn’t make known his intentions, then the female could eat him for a meal.

Figure 5. A male starting his ritualistic courtship dance.

The female, once impregnated, will lay up to one hundred eggs in a secluded spot. However, unlike most spiders she creates a silk sac which she uses to encase the eggs. She attaches the egg sack to her abdomen, specifically her spinnerets. She defends her eggs and babies with her life. In two to three weeks the mom will take off the egg sac and rip it open. Baby spiders swarm out and clamber on top of the mom’s abdomen. They’ll remain there until their first molt. Throughout this the mother doesn’t change her hunting patterns. The young don’t feed while on their mom but they do drink dewdrops. The average life span of the Lycosa furcillata is about two years.

Figure 6. A female Lycosa furcillata with her egg sac.

Figure 7. A mother with her babies.

Unlike other animals, the spider excretes digestive enzymes in its venom. The spider has tiny hairs around and in the mouth which filters the liquefied guts. The nutrition then enters the sucking stomach and into the midgut. In the midgut, the meal is furthered digested into manageable molecules. At the end of the midgut there is a cloacal chamber where the fecal matter is stored. The fecal matter will later be expelled.

IV. Impact on the World

Lycosa furcillata and humans can easily come in close contact in Florida, especially when the spider enters into our homes. The spider only bites when handled or provoked. It does produce venom, however, the bite is only slightly painful and there are no long lasting repercussions. Other than this, the wolf spider can be very beneficial to humans because the spider can control pest populations in agriculture and home areas.

Figure 8. Wolf spider

V. Journal Article

Unfortunately, I was unable to find an article specifically on the Lycosa furcillata but I did find a super awesome article on another wolf spider.
A scientist did a study on certain chemicals that prey can pick up on that occur during feeding habits of the Hogna helluo. There were three sheets of blank paper. On one of the sheets a Hogna helluo hunted down and devoured the wolf spider Pardosa milvina. On another sheet, the Hogna helluo devoured crickets and on the third sheet was a blank control where nothing occurred.
There was a significant change in behavior in the P. milvina when on the sheets of paper. On the sheet where the Hogna helluo ate a Pardosa milvina, the living P. milvina stayed still and didn’t move. On the cricket sheet, the P. milvina elicited more activity. And on the blank sheet the P. milvina was most active. If given a choice the P. milvina chose the blank control much more often than the other two sheets where the Hogna hunting had occurred.

I wasn't able to download and upload the video, sorry :(

But it is a really cool video on a Lycosa eating a katydid

Works Cited:

"FAMILY LYCOSIDAE - Wolf Spiders." Web. Apr. 2011. .

Nieuwenhuys, Ed. "Wolf Spiders." XS4ALL - Internet, Bellen, Televisie En Hosting. 2009. Web. Apr. 2011. .

Olli. "Wolf Spider Mating Dance Flickr - Photo Sharing!" Welcome to Flickr - Photo Sharing. Flickr. Web. 29 Apr. 2011. .

"There Are about 40,000 Kinds of Spiders." - Doing It In Just One Visit. Temidor Certified. Web. Apr. 2011. .

"Wolf Spider Lycosa Furcillata Female." Australian Venom Research Unit. Web. Apr. 2011. .

"Wolf Spider." Spider Bites. Bad Spider Web. Apr. 2011. .

"Wolf Spider." Wikipedia, the Free Encyclopedia. Wiki. Web. Apr. 2011. .

"Wolf Spiders." Entomology & Plant Pathology, Division of Agricultural Sciences and Natural Resources. Web. Apr. 2011. .

"Wolf Spiders (Lycosidae)." Green Nature. Web. Apr. 2011. .

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