Red Knee Tarantula

Quick Take

• This tarantula's defense has nothing to do with its bite, and it is capable of temporarily blinding a predator. See the defense mechanism →
• Female red knee tarantulas outlive males by a jaw-dropping margin, a difference that is tied to something they do every few years. Discover the lifespan gap →
• Its venom doesn't kill prey the way most people imagine. What actually happens is far stranger. See how venom works →
• Tarantulas existed before most continents did, and understanding where they came from changes everything about how we think of them as a 'New World' spider. Explore their ancient origins →

Instead of spinning a web, these spiders dig burrows and spend most of their lives underground. They have a long lifespan compared to other spiders. Males can live up to ten years, whereas females can potentially reach 30 years old. They are carnivores, eating a diet of crickets, grasshoppers, roaches, lizards, frogs, and sometimes small mice.

5 Incredible Red Knee Tarantula Facts

• This spider is one of over 1,000 species of tarantula.
• These tarantulas hide in their burrow waiting to grab an insect or rodent passing by.
• The eight eyes on the head of this spider allow it to see what’s in front of it and behind it.
• A female red knee tarantula can lay from 200 to 400 eggs at a time.
• There are two claws on the end of each leg that allow this spider to climb a slick surface.

Classification and Scientific Name

The scientific name of the red knee tarantula is Brachypelma hamorii (formerly known as Brachypelma smithi). The Greek word Brachypelma means “short sole/foot,” derived from brachys (short) and pelma (sole/foot). The word smithi relates to this particular species of tarantula. Red knee tarantulas, also called the Mexican red knee tarantula, belong to the family Theraphosidae and the order Araneae.

There are more than 1,000 species of tarantula. Unlike other spiders, tarantulas always have hair on their body and legs. Also, while most spiders have six spinnerets for spinning webs, some types of tarantulas have four spinnerets while others have two. Furthermore, like all spiders, tarantulas have specialized glands in their abdomen that produce silk, though some tarantula species may also secrete silk from structures on their feet.

Evolution and Origin

Tarantulas first appeared in the Americas about 120 million years ago. The spiders that were ancestors to the African tarantulas appeared close to 112 million to 108 million years ago. However, by the 108 million year mark, tarantulas emerged from what is now known as India.

As mentioned above, the first known tarantulas appeared in the Americas. However, at the time, South America would have been connected to Africa, India, and Australia as part of the Gondwana supercontinent.

Spiders are an extremely ancient group.

Appearance

The red knee tarantula has a large abdomen featuring dark brown hairs. Its cephalothorax features dark brown and cream-colored hairs. This spider has bright red or orangish hairs on each of its knee joints. This coloration earned this spider its name.

The hairs on this spider’s legs are adapted to sense vibrations in the ground. The vibrations help these spiders to safely navigate their environment. They also have palps that help them taste and smell.

Baby red knee tarantulas, or spiderlings, don’t have the full coloration of adults. Their bodies don’t start to take on the dark brown and red/orange color pattern until they are several months old.

Red knee tarantulas are five to five and a half inches long and weigh an average of 0.5 ounces. This spider’s leg span can reach up to 10 inches.

When threatened by a predator, a red knee tarantula typically retreats to its burrow. Sometimes it stands up on its back legs to reveal its fangs to scare the threat away. Notably, this spider has barbed hairs on the underside of its abdomen.

It can flick these barbed hairs at predators to defend itself. These hairs can lodge in a predator’s body, causing itching and irritation. If they land in a predator’s eyes, they can cause temporary blindness.

This tarantula leads a solitary life except during the breeding season.

Habitat

Red knee tarantulas can be found primarily in Mexico, with their range extending into Panama and parts of the southwestern United States. They live in a desert habitat as well as in scrublands and dry forests. In a desert, this spider may dig a burrow at the base of a cactus.

Red knee tarantulas have a shy temperament and look for hiding places. A wild red knee tarantula may find its way into a shed or garage and make a home between a stack of old boxes or behind a dusty collection of brooms, shovels, etc. Otherwise, if a red knee tarantula is in a house, it’s usually a pet.

Diet

Red knee tarantulas are carnivores. One of the most notable facts about these spiders is that they usually let their food come to them. This spider hides in its burrow and waits for a lizard, cricket, or other prey to enter the area. When the animal gets close enough, the tarantula grabs it and gives it a venomous bite. Once the prey is paralyzed, the venom liquefies its insides. The spider then consumes the liquefied insides.

What eats the red knee tarantula?

Predators of this colorful spider include birds, large lizards, and the Pepsis wasp, aka the Tarantula hawk wasp.

A baby red knee tarantula is even more susceptible to being captured by a predator.

What does the red knee tarantula eat?

These spiders eat crickets, grasshoppers, rodents, small lizards, frogs, and roaches. They eat whatever animal is most abundant in their desert habitat. Baby tarantulas eat the same types of prey, but smaller ones.

These spiders typically eat once or twice per week. A month or two before molting, these tarantulas usually stop eating. This allows them to focus energy on the stressful molting process. A tarantula molts many times throughout its long lifespan.