The webs of a triangle spiders may have zig-zags (stabilimentum) running across them. This pattern is a result of the spider's vibrations from walking on the web. It is thought to blur the outline of its web, gaurding against detection by predators and potential prey.
US Federal List: no special status
CITES: no special status
Triangle spiders, unlike most spiders, have no venom glands. For this reason they must rely solely on web weaving abilities for prey capture. Targeted prey usually include small flying insects, such as flies and moths. These insectivores use triangular webs as a snare to catch and entangle victims. By forming a Y-shaped framework with four attached radii between twigs or tree branches, these spiders can construct their triangluar webs. Triangle spiders then position themselves, outstretched along the frame of the web, holding back any slack with their legs. As an insect flies into the web, the spider tightens and releases excess slack to entangle the insect within the woolly (cribellate) silk strands. If the insect struggles, H. paradoxus will turn its back and use its spinnerets to wrap the insect with a thick, blueish silk until the prey is completely shrouded. Once the prey has been immobilized, the spider uses its jaw mechanism to break apart its body, while the maxillary glands secrete powerful digestive enzymes to break down the internal organs. Finally, H. paradoxus is able to harvest the liquified protein of its meal by using its sucking stomach.
Animal Foods: body fluids; insects
Primary Diet: carnivore (Insectivore )
Triangle spiders, Hyptiotes paradoxus, are found throughout the continental United States and most of Northern Europe.
Biogeographic Regions: nearctic (Native ); palearctic (Native )
Triangle spiders mostly occupy wooded landscapes, such as forest groves, mountain terrain, and grassy plains. Populations have been discovered clustered within hollow trees and underneath rocky ledges. Commercial greenhouses have often attracted these spiders presence as well.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: taiga ; savanna or grassland ; forest ; mountains
Other Habitat Features: agricultural
Triangle spiders are relatively small in size, only 2 to 4 mm long. The carapace is noticeably flat, and wide to support the thick, oval shaped abdomen. A few minute bumps are apparent on the abdomen, disguised by short, stiff hairs. The coloring varies from brown to grayish, enabling these spiders to blend with the environment. Hyptiotes paradoxus was once believed to have only six eyes due to dense hair coverage of the other two. Males, although smaller in size than females, bear a close resemblance.
Range length: 2 to 4 mm.
Other Physical Features: ectothermic ; bilateral symmetry
Sexual Dimorphism: female larger
Males reach maturity in the early fall. Before searching for a mate, a male must first charge his reproductive organ with sperm. He does this by constructing a web, on which he deposits semen from the rear genital opening. Hanging from the web frame, he uses his legs to pull the web strand closer and draw the semen into his claw-like palp.
Having extremely small eyes, a male must rely on recognition of a female's cribellate silk dragline to track her. Females coat their silk with a sexual scent (pheremone) which attracts males. Since triangle spiders are short-sighted, vibrations sent along the web are the primary means of courtship.
When mating begins, the male inserts the embolus spur on the tip of his palp into the female's reproductive structure (epigyne). The female's resevoir absorbs the flow of sperm, where it will be stored until her eggs are ready for fertilization.
After her eggs develop within the ovaries, they are ready to be laid. First, the female weaves a woolly sheet of silk on which to deposit her eggs. As the eggs are laid, she covers them with a sticky substance containing the male's sperm. The permeable lining of the eggs allows sperm in to complete fertilization. Continuing to wrap the eggs in silk, she creates a protective egg sac. The elongated sacs are then strung across the triangular web in a row, where she aligns her body to blend with them. Within the sac, the postembryo soon disgards its outer covering (integument) and emerges a first-instar spiderling.
Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); oviparous ; sperm-storing
