Spiders: Arthropods of the class ARACHNIDA, order Araneae. Except for mites and ticks, spiders constitute the largest order of arachnids, with approximately 37,000 species having been described. The majority of spiders are harmless, although some species can be regarded as moderately harmful since their bites can lead to quite severe local symptoms. (From Barnes, Invertebrate Zoology, 5th ed, p508; Smith, Insects and Other Arthropods of Medical Importance, 1973, pp424-430)Spider Venoms: Venoms of arthropods of the order Araneida of the ARACHNIDA. The venoms usually contain several protein fractions, including ENZYMES, hemolytic, neurolytic, and other TOXINS, BIOLOGICAL.Spider Bites: The effects, both local and systemic, caused by the bites of SPIDERS.Black Widow Spider: A venomous New World spider with an hourglass-shaped red mark on the abdomen.Silk: A continuous protein fiber consisting primarily of FIBROINS. It is synthesized by a variety of INSECTS and ARACHNIDS.Fibroins: Fibrous proteins secreted by INSECTS and SPIDERS. Generally, the term refers to silkworm fibroin secreted by the silk gland cells of SILKWORMS, Bombyx mori. Spider fibroins are called spidroins or dragline silk fibroins.Predatory Behavior: Instinctual behavior pattern in which food is obtained by killing and consuming other species.Brown Recluse Spider: A spider of the genus Loxosceles, found in the midwestern and other parts of the United States, which carries a hemolytic venom that produces local necrosis or ulceration.Atelinae: A subfamily in the family ATELIDAE, comprising three genera: woolly monkeys (Lagothrix), spider monkeys (Ateles), and woolly spider monkeys (Brachyteles).Arthropod Venoms: Venoms from animals of the phylum Arthropoda. Those most investigated are from scorpions and spiders of the class Arachnidae and from ant, bee, and wasp families of the Insecta order Hymenoptera. The venoms contain protein toxins, enzymes, and other bioactive substances and may be lethal to man.Arachnida: A class of Arthropoda that includes SPIDERS; TICKS; MITES; and SCORPIONS.Agatoxins: A class of polyamine and peptide toxins which are isolated from the venom of spiders such as Agelenopsis aperta.Cannibalism: Eating other individuals of one's own species.Neurotoxins: Toxic substances from microorganisms, plants or animals that interfere with the functions of the nervous system. Most venoms contain neurotoxic substances. Myotoxins are included in this concept.