An orange dragonfly perches on a stick. Half of its wings are transparent.
Invertebrates like this dragonfly are the most numerous wildlife in the monument. From tiny ants to large tarantulas, invertebrates make up important parts of the Sonoran Desert ecosystem. Offering services such as cleaning up carrion, or providing food to larger organisms, which then feed even larger critters, invertebrates may be small, but their world is expansive.

NPS Photo

Animals that evolved without back bones or "vertebral columns" are called invertebrates. Invertebrates are a massive group of organisms outnumbering any other group (or combined group) of animals on Earth. Invertebrates are incredibly diverse, ranging from jellyfish, slugs, and squids, to flies, spiders, and worms, and everything in between. Invertebrates make up important parts of the Sonoran Desert ecosystem, from tiny ants to large tarantulas filling specific roles. Offering services such as cleaning up carrion, or providing food to larger organisms, which then feed even larger critters, invertebrates may be small, but their world is expansive.
A tarantula hawk with bright orange wings sits at a body of water.

NPS photo

Tarantula Hawk (Pepsis thisbe)

Tarantula hawks are large wasps with a powerful sting. Regarded as the second most painful insect sting or bite, this tarantula hawk commands respect in the deserts where they are found. Female tarantula hawks scan the ground looking for tarantulas, to which they deliver a paralyzing sting. The wasp then drags the helpless spider to a den, and lays a single egg, which hatches into a larva. The larva will eat the spider while carefully keeping it alive, until it transforms into an adult wasp, starting the lifecycle over.

Identify this Invertebrate

Tarantula hawks are roughly the size an adult’s thumb. They have black bodies that glint blue in the sunlight, and bright orange wings that offer contrast to the body. This bold coloration, called “aposematism” lets predators know that they are not to be messed with and will deliver a painful sting. Watch for these large wasps flying over the ground, methodically scanning for tarantulas.

A glossy brown millipede crawling over gravel.

NPS photo

Arizona Giant Millipede (Orthoperus ornatus)

The Arizona giant millipede is stocky bodied and ground dwelling, slowly moving along the landscape. Millipedes have two pairs of legs on each body segment and add more after they shed. Although the Latin roots to the word “millipede” suggests these slinky creatures have 1000 legs, the most they may have is about 750. When they feel threatened, millipedes curl up into a tight spiral, and squeeze out bad tasting liquid from near their legs.

Identify this Invertebrate

These many-legged critters are glossy black to red-brown, and can be as long as your hand, with larger specimens measuring 9 inches (23 cm). Their bodies are between the thickness of a pen and a marker. Compared to a desert giant centipede, the this millipede is round instead of flat, moves slower, and has many more and smaller legs.

A hairy tarantula crouched on gravel, with their legs pulled in close to their body.

NPS photo

Desert Blonde Tarantula (Aphonopelma chalcodes)

The desert blonde tarantula is a large spider that lives in burrows, and ambushes its prey. These spiders often perch just behind the entrance of their burrow and use their venom to paralyze prey such as grasshoppers. This tarantula is neither skittish, nor aggressive, making it a fun and interesting spectacle of the Sonoran Desert.

Identify this Invertebrate

The desert blonde tarantula is roughly palm-sized, with a dark body covered by lighter colored hairs. Females are larger, fuller bodied, and lighter colored. Males are seen more often, as they wander farther in search of mates. Keep a look out for these spiders at night along roadsides and trails. These spiders blend into their surroundings, but their eyes shimmer when a flashlight is shown on them.


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Invertebrates in Arizona

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    Last updated: August 19, 2023

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