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Bio Facts: Red-kneed Tarantula
Common Name: Red-kneed Tarantula Red-kneed Tarantula
Scientific Name: Brachypelma smithi
Family: Theraphosidae
Order: Araneae
Class: Arachnida
Range: Western Mexico
Habitat: Dry deciduous forests and lowland scrub
Description: The red-kneed tarantula has reddish orange markings on the legs, especially close to the body.  Leg spans are up to 6 inches.  The cephalothorax tends to be blackish with brownish border.  The abdomen is black.  The color tends to deepen with maturity.
Life Expectancy: 20+ years for females, and approximately 5 years for males
Sexual Maturity: 4 to 7 years
Diet: In the wild, they eat crickets, grasshoppers, small snakes, frogs, spiders and worms.  At the Zoo, they are fed crickets, mealworms, and small pinky mice.
Status: CITIES - Appendix II
Behaviors:

The red-kneed tarantula is a nocturnal animal that hides inside of a burrow to avoid the sun.

Mature males are nomadic and mate with mature females from mid- to late-summer (July to October).  Two to four hundred eggs are deposited in the cocoon web lining the burrow, or in a bowl-shaped cocoon web constructed in hollows between or beneath rocks or natural debris.  The female guards the egg sac and turns it and moves it around to ensure proper humidity and temperature controls.  Babies emerge simultaneously approximately nine weeks after laying and remain with the mother for 12 to 16 days before dispersing.  Predation and other natural causes may account for up to 98% mortality rate in young spiders.  Males mature at approximately the 20th instar (the stage between molts that comes at about age 4 years) two to three years before females (age 6 or 7 years). 

Courtship proceeds in a face-to-face manner until the female is tempted into the threat attitude in which the jaws are opened wide.  At this point, the male locks her jaws open with a special pair of spurs situated on his front legs.  The two then push one another up in a reared-back position.  With his second set of legs, the male holds the female down and bends her backwards.  Then he reaches under to transfer the sperm from his pedipalps to the epigastric furrow at her midsection.  Afterward the male releases one of the female’s fangs and positions his legs for a quick retreat.  It is not uncommon for a female to turn and consume her mate afterward.  He is a handy source of protein for her newly fertilized eggs.

Tarantulas live in short burrows in the ground.  A web carpet extends from the burrow out and across the opening, but is usually covered or coated in the substrate of the area.  Safely hidden in the burrow, the tarantula waits for prey to walk across the web.  When detected by vibrations sent through the web, the tarantula rushes out of the burrow grabs and bites the prey, retreating back into the burrow.  After ingesting the prey’s insides, the tarantula typically wraps it in a web and takes it to another area of the burrow.
Adaptations:

The red-kneed tarantula has a delicate exoskeleton that can shatter if the animal is dropped or is touched improperly.  Molting takes place once or twice a year.  This spider will not eat when it is about to molt and will sometimes go for months without food.

Tarantulas have two large fangs.  The venom enables the tarantula to subdue its prey and allows the digestive process to begin.  The venom contains strong digestive enzymes that break down the interior part of the prey bitten.  Once “liquefied”, the tarantula devours its prey by sucking the juices from its body.

For defense, the tarantula kicks guard hairs off of its abdomen that can cause an allergic reaction on the skin (rash and itching) and burning in the eyes.  If inhaled, they can cause severe irritation to the respiratory tract. These hairs may be fatal to small rodents.
Special Interest:

It is a myth that the bite of a tarantula is fatal.  The bite of most tarantulas is similar to a bee sting, and is not fatal to humans except possibly for those that have an allergic reaction to the venom.

Spiders comprise a large, widespread group of carnivorous arthropods.  They have eight legs, can produce silk, and have poison glands associated with fangs.  More than 30,000 species of spiders are found on every continent except Antarctica.  More than 850 species of tarantula have been described.

After handling a tarantula bare handed, it is not uncommon to have a slight allergic reaction on the skin (rash and itching).  Wash all exposed skin areas well after exposure to minimize this effect.  If one has particularly sensitive skin, it is not recommended that this animal be handled without gloves.
Folklore:

An old English word for spider was attercop, meaning “poisonhead.”  Our word cobweb is derived form this old English term.

For centuries folk healers have prescribed spiders and spider webs as medicine.  Dr. Thomas Muffet, a physician, recommended swallowing spiders to cure various illnesses.  In fact, he practiced some of these remedies on his unfortunate daughter.  From this came the nursery rhyme:

              There came a big spider,

              And sat down beside her,

              And frightened Miss Muffet away.

American Indians believe that when a person dies, he or she climbs to the heavens on ropes of spider silk.  The Apache honor Grandfather Spider, for it was he who made a ladder of sunbeams so they might beam up from the center of the Earth.  The Hopi believe Grandmother Spider is a messenger of the sun spirit.  The Cherokee believe that she brought the first fire into the world by snatching a bit of the sun.  The Chippewa hang real spider webs on the hoops of a baby’s cradleboard so any harm floating in the air would be caught in the web.

Some African tribes look upon the spider as a national hero and believe it to be shrewd, designing, and a selfish trickster.  An Ethiopian proverb says, “When spider webs unite, they can tie up a lion.”
Conservation: Mexican legislation is very general and prohibits all hunting and exporting of wild animals except under license.  The issuing of licenses is subject to the scrutiny of experts, who determine quantities that may be collected, and from where.  The demand for unusual and exotic pets has increased dramatically and is considered a primary reason for developing additional conservation measures for the red-kneed tarantula.
Jacksonville Zoo History: Red-kneed tarantulas (Brachypelma smithi) have appeared in the collection off and on since April 1977.  This is the earliest recorded invertebrate specimen that can be verified by Jacksonville Zoo records since its opening in 1914.
Revised: December 2001