Invertebrates

Tarantulas are seen in the park during the day from time to time. Females can live for more than 20 years.

NPS Photo

Hundreds of species of insects, arachnids and other invertebrates find a home in the unique ecosystems of Montezuma Castle National Monument. These include harmless tarantulas as well as venomous black widow spiders and Arizona bark scorpions. However, these often misunderstoood desert inhabitants pose little threat to humans. The invertebrates found at Montezuma Castle and Montezuma Well reveal extraordinary evolutionary adaptations for survival in an arid desert environment.

 

Adult tarantula

NPS Photo

Tarantula (Aphonopelma spp.)

Tarantulas are the largest spiders found in the continental US and some of the desert's most famous residents. Three species call the Verde Valley home. In spite of their intimidating appearance, tarantulas are calm and docile. Bites are very rare and their venom is not considered harmful to humans. Instead, tarantulas may flick bristles off of their abdomen at threats which can cause skin irritation.

They are most active during monsoon season from July through September which also coincides with their breeding season. They are most active at night, but are occasionally seen during the day. Tarantulas spend much of their time in silk-lined underground burrows either avoiding the heat of the day or waiting for prey to wander near their burrow. Tarantulas feed on lizards, insects, centipedes, and even mice.

 

Tarantula hawk with huntsman spider

NPS Photo

Tarantula Hawk (Pepsis spp.)

Tarantula hawks are large wasps named for their behavior of hunting tarantulas. Four species are found in the Verde Valley. All species are black with iridescent, bluish bodies, and most often have orange or brown wings. Females hunt tarantulas and other spiders and sting them to paralyze the spider. Once paralyzed, the wasp drags the spider to a burrow where she lays a single egg on the spider and covers the burrow. Once the egg hatches, the larva slowly eats the spider alive before emerging from the burrow. Adult tarantula hawks are pollinators and feed on nectar.

Tarantula hawks are also famous for having one of the most painful stings of any insect in the world, though the pain only lasts about 15 minutes. However, like the tarantula, these intimidating wasps are not aggressive and will only sting if provoked.

 

Crayfish (Faxonius spp.)

Crayfish, also known as crawdads and crawfish, live in freshwater habitats such as streams, rivers, swamps, and ponds. There are over 500 species worldwide and about 150 species in North America. Crayfish are not native to Arizona. Originally released into reservoirs and large bodies of water as a food source for sport fish by people unaware of the devastating consequences, crayfish have invaded previously pristine waters negatively impacting native fish and aquatic ecosystems. This primarily nocturnal, armor-covered crustacean has few natural predators, is omnivorous, and competes for resources with fish, frogs, insects, and turtles. The crayfish propels itself backward through the water by using its tail composed of a central section called a telson and uropods on each side. It is able to walk on land and in the water by using its 4 pairs of walking legs. Each leg has an attached gill that occupies the bronchial chamber. The crayfish senses its world with its eyes, two pairs of antennae, and pincers called chelipeds. Crayfish have the ability to regenerate lost limbs. They molt as they grow, and often eat the old shell.