Plectreurid spiders (familyPlectreuridae) belong to a small family confined to the North Americandeserts and the island of Cuba. Only two genera are known - the nominate genus Plectreurys and Kibramoa. These ecribellate (lacking a plate-like wooly silk-producing structure anterior to the spinnerets on the venter), haplogyne spiders build haphazard webs under rocks and dead cacti. Relatively little is known of their biology. Unlike the sicariids, scytodids and diguetids, to which they are related, they have eight eyes. In appearance females of Plectreurys resemble those of the larger species of the cribellate Filistatidae. They differ in there eye arrangement and in having the first femora (third leg segment from the body) bowed.
Spiders reproduce by eggs laid in silk bundles called egg sacs, and the male (usually significantly smaller than the female) is likely to be killed by the female after the coupling, or sometimes before intercourse has occurred.
When sexually mature, a male spider will spin a web pad onto which the contents of the abdominal reproductive organs are discharged and then the seminal fluid is transferred into the cavities of the palpi; when an individual secures a mate he thrusts the palpi one at a time into her abdominal genital openings.
The widow spiders, brown recluse spiders, hobo spiders, and yellow sac spiders are the dangerous ones among U.S. spiders.
The spider's respiratory anatomy is based on a tracheal system, with each opening to the trachea as an extension of an outer pore reaching from the spider abdomen, protected by spiracles which are pores in the spider exoskeleton, composed of chitin.
Spiders reproduce by eggs laid in silk bundles called egg sacs, and the male (usually significantly smaller than the female down to 1% for Tidarren sisyphoides) is likely to be killed by the female after the coupling, or sometimes before intercourse has occurred.
Normally, fl widow spider bites are fatal only to children, due to the fact that children have much smaller body weights than adults and so the poison is more concentrated in their bodies when a bite does occur.
Feeds |
Contact