BIOL 2030 Chapter Notes - Chapter 7: Spider Anatomy, Pedicellaria, Cephalothorax
26 Apr 2016
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Cephalothorax (all joined appendages here: small chelate chelicerae, large chelate pedipalps, 4 pais of walking legs, 3 groups of simple eyes. 2nd sternite (abdominal segment) pectines [comb-like, sensory in fn. ] 1st sternite genital operculum obscures gential opening. 6th basal bulb (produces toxin) + sting. Ventral: cephalothorax + abdomen (note pectines on 1, and spiracles on 2) Cephalothorax & abdomen connected by pedicel: superficially unsegmented. Anterior: 2-jointed chelicerae @ front: distal fang-like, tube inside opening @ tip (comm. w venom gland in basal joint) Abdomen: 1st sternite pedicel, 2nd epigastric furrow(a transverse line) Genital opening [medial, slightly anterior to furrow: 3rd & 4th spinnerets (4); - silk-producing. 1st somite pair of jointed poison claws[tarsungulum] (duct from poison gland opens @ tip) Each somite (except last two) pair 7-jointed legs: last pair longest, used in defence. Last 2 segments pregenital & genital segments. Marine, no head, no brain, no segmentation; sedentary/slow-moving. The nervous system: circumoral ring + radial nerves (reduced)
