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Unformatted text preview: containing venom. Ticks, shown in Figure 17, are parasites that suck blood and sometimes transmit diseases. Chiggers are larvae of certain mites and feed on the skin of vertebrates. Spiders, shown in Figure 18, have a narrow waist separating the cephalothorax from the abdomen. Spiders have numerous simple eyes rather than compound eyes. The chelicerae are modified as fangs with ducts from poison glands. The abdomen has silk glands used to spin a web to trap prey. Invaginations of the body wall form lamellae (pages) of the book lungs; air flows across the lamellae in the opposite direction from blood flow to exchange gases more efficiently....
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- Fall '10
- Biology, Spider, Arachnid, Chelicerata, class arachnida