Back to Insects Arachnids: Class Arachnida Arachnids are a class of arthropods that contain some large orders such as spider, ticks/mites, harvestmen, scorpions, and more. They can be distinguished from insects by having 4 pairs of legs, no antennae, a cephalothorax & abdomen, and chelicerae instead of mandibles.
Spiders: Order Araneae
Black Widows Latrodectus spp. The Black Widow is a common name that refers to a few different species in the genus Latrodectus. Widow spiders are some of the most notorious spiders, mostly due to the fact that they are one of only two spiders considered to have a medically significant bite here in the U.S. Despite this, they are timid spiders that would much sooner run away than use any of their precious venom on you. The only times bites occur are when they are being grabbed/squeezed accidentally and feel threatened. In order to avoid this, it’s best to know where to look so you don’t disturb them! Look for this cobweb weaver building its web in shaded areas close to the ground. If you don’t mess with them, they make for great pest control, too. The juvenile form of the Black Widow is a mottled, yellowish-white color. As it matures, this spider gradually turns black until only the distinctive hourglass mark remains on the lower abdomen. Males are usually smaller than females with longer legs, and they often exhibit a distinct white and black coloration.
Flatties Selenops spp. Spiders in the genus Selenops are often called “Flatties” for their thin and flat appearance. While their common name might not be the most creative, the etymology behind the name for the genus is more interesting. The name is a combination of two Greek words, “selene-” meaning moon/crescent, and “-ops” meaning eye. Some other interesting facts about these Flatties are their unique ability to glide and maneuver in the air while falling. They also have one of the fastest turning movements of all terrestrial animals, which, when coupled with the large field of view provided by the crescent eye layout, allows them to attack prey omni-directionally. This suits their role of being cryptically camouflaged ambush predators.
Flower Crab Spider Misumenops celer The coloration of the flower crab spider varies greatly, ranging from white to yellow, or even a bright green. Male flower crab spiders have red markings along the outer edge of their bodies and small bands of red on their two front legs. The front legs of the female are lighter in color and lack the red markings. Flower crab spiders are commonly found in cotton plants, and on certain cactus flowers.
Garden Orb Weavers Argiope spp. These spiders in the genus Argiope are known for weaving large orb webs, often low enough that you could walk through them. Luckily, their bright colors and a banded silk pattern, called a stabilimentum, helps make them more visible to prevent larger animals or people from accidentally destroying their webs. They often align their legs with the pattern of the stabilimenta, often forming an “X”. These brightly colored spiders are usually striped and have a silvery carapace. These are very beneficial spiders to have around, as they are an efficient natural pesticide service! Females can lay between 400-1400 eggs in an egg sac.
Giant Crab Spider Olios giganteus Giant Crab spiders are another common name for Huntsman spiders in the family Sparassidae. The most iconic Giant Crab spider here in the states is Olios giganteus. Like all Huntsman spiders, O. giganteus is a speedy predator that chases down its prey. They can be identified by their darkened chelicerae, a prominent heart mark (not the standard heart shape, rather a darkened patch over their actual heart), and rotated legs (which gives them the crab shape).
Green Lynx Spider Peucetia viridans Named for the bright green color of its body, the green lynx spider can be found hidden among flower blossoms. The bright green color helps the green lynx to blend with its environment in order to stalk its small insect prey. The legs of the green lynx are more yellowish than the rest of the body and covered in short black spines. Spiderlings are bright orange immediately after birth. Female green lynx spiders tenaciously guard their straw-colored egg sacs, often constructing protective shelters out of scattered leaves. The egg sacs of the green lynx can contain from 150 to 600 eggs
Jumping Spiders Phidippus spp. Terrifying predators of the insect world, jumping spiders are avid hunters. Their large, forward-facing eyes, coupled with their impressive leaping ability make them highly successful at catching their prey. Jumping spiders have two breathing systems: a book lung and tracheal system. With both of these being well developed, jumping spiders have bimodal breathing. Their eyes are some of the best of all arthropods and are relied upon heavily in hunting, navigation, and even courtship for some species.
Recluse Spiders Loxosceles spp. While the iconic Brown Recluse does have part of its natural range in Texas, it does not actually extend this far west. The species of recluse spider that we have here in the park is Loxosceles blanda. Recluse spiders are known for their necrotic venom, though most bites resolve themselves without significant medical intervention. Additionally, these spiders are not aggressive and are reclusive by nature--often times people can exist in close proximity with recluse spiders and never receive a bite.
Spotted Orb Weavers Neoscona spp. One of the other spiders found here that makes large, intricate orb webs are the Spotted Orb Weavers in the genus Neoscona. There are only 8 species described here in the U.S., each with fairly unique and distinguishing patterns. These spiders are often confused with spiders in the genus Araneus; however, these spiders have a longitudinal groove in their carapace that distinguishes them. One of the larger and more intimidating Spotted Orb Weavers here is the Western Spotted Orb Weaver, Neoscona oaxacensis. Identifiable from its mottled yellow on black coloration, N. oaxacensis makes large orb webs to capture prey.
Tarantulas Aphonopelma spp. Fairly common throughout the State of Texas, tarantulas are burrowing spiders that are easily identified by their large size. There are 14 species of tarantula found throughout Texas and specific identification is difficult even to those with the proper equipment, literature, and experience. However, some varieties from Northern Mexico are easier to identify due to their unique color pattern. Female tarantulas generally live longer than male tarantulas in Texas and can lay from 100 to 1000 eggs in their burrows. Texas species of tarantula generally remain in burrows and their bite is painful, but not harmful to humans. Despite their venom not being dangerous to humans, the tarantulas here in the Americas have an additional defense: urticating hairs. These hairs are kicked off at the spiders’ attacker and cause irritation when they make contact with skin.
Wolf Spiders Family Lycosidae Wolf spiders are active hunters; they rarely create burrows or spin webs. They are largely nocturnal and hunt using their large, forward facing eyes to attack their prey. Females will lay silk lines along with pheromones to attract mates from far away, and there are multiple different courtship routines/methods depending on the species. The mother wolf spider will carry her babies on her back until they are ready to go off on their own.
Harvestmen: Order Opiliones Harvestmen (also sometimes called “daddy longlegs”) are distinguishable from spiders by the apparent fusion of the cephalothorax to the abdomen, giving them the appearance of having only one body segment. They also only have one pair of eyes, compared to the three to four pairs found on true spiders. Harvestmen also pose no threat to humans, as they lack venom glands. In addition to lacking venom glands, this order of arachnids also do not produce silk, and therefore do not make webs. They are opportunistic omnivores, feeding on a wide range of foods from fungi to small insects. Harvestmen are also an ancient order of arachnids, with fossilized specimens from 410 million years ago appearing similar to their modern counterparts, suggesting that they have been on land for even longer.
Camel spiders/Wind scorpions: Order Solifugae
Straight-Faced Solifugid Family Eremobatidae Also known as wind scorpions, straight-faced solifugids are characterized by their distinctive, vertically curved jaws. Unlike other scorpions, they are only able to walk on three pairs of legs, using their slender first pair as sensor organs. Though many people wrongly consider these nocturnal wind scorpions venomous, they lack venom sacks. They are, however, capable of inflicting a painful bite. Like spiders, males are generally smaller and have longer legs. Straight-Faced Solifugids only live up to one year.
Scorpions: Order Scorpiones
Striped Bark Scorpion Centruroides vittatus The striped bark scorpion can be recognized by two broad, black bands along the top of its abdomen. Color can vary from yellowish to light tan in adults of the species while younger striped bark scorpions are darker in color. Striped bark scorpions mate in fall, winter, and early spring, and have a lifespan of up to four years. The sting of this scorpion causes swelling and localized pain.
Whipscorpions: Order Uropygi
Vinegaroon Mastigoproctus giganteus The three-inch body of the vinegaroon makes it the largest known whip scorpion. Unlike other nocturnal creatures, the vinegaroon has poor eyesight and relies on its keen senses to feel vibrations and find its prey. Though it prefers a desert habitat it is also common in grasslands. The vinegaroon has no stinger, but its whip-like tail sprays an acidic solvent that can eat through the exoskeleton of other insects and smells remarkably like vinegar