Fig. 23-1, p.360

Table 23-1, p.361

Fig. 23-2, p.361 ventral posterior dorsal anterior

Fig. 23-3, p.363

Fig. 23-6, p.364 choanoflagellates placozoansspongescnidariansflatwormsrotifersmollusksannelidsroundwormsarthropodsechinodermschordates multicelled body no true tissues true tissues radial ancestry, two germ layers protostomes, mouth forms first in embryos bilateral ancestry, three germ layers deuterostomes, anus forms first in embryos fungi

Fig. 23-7, p.365

Fig. 23-8, p.365 nucleus glassy structural elements ameboid cell pore semifluid matrix flattened surface cells collar cell central cavity water out water in water in flagellumcollar of microvilli

Fig. 23-9, p.366

Fig , p.366 capsule's trigger (modified cilium) lid barbed thread in capsule nematocyst (capsule at free surface of epidermal cell) barbs on discharged thread exposed

Fig , p.367

Fig , p.367 male medusa ciliated bilateral larvagrowth of a polypone branch of a colony ovum sperm zygote feeding polyp reproductive polyp female medusa

Fig , p.368 rudimentary brain (pair of large ganglia in head) branching gut pharynx; protrudes onto food, then retracts into the body between feedings ovary testis oviduct genital pore pair of nerve cords that have lateral branchings

Fig , p.369

Fig , p.369 proglottids Larvae, each with inverted scolex of future tapeworm, become encysted in intermediate host tissues (e.g., skeletal muscle). A human, the definitive host, eats infected, undercooked beef, which is mainly skeletal muscle. Each sexually mature proglottid has female and male organs. Ripe proglottids containing fertilized eggs leave the host in feces, which may contaminate water and vegetation. Inside each fertilized egg, an embryonic, larval form develops. Cattle may ingest embryonated eggs or ripe proglottids, and so become intermediate hosts. one proglottid scolex attached to wall of intestine scolex

Fig , p.370

Fig , p.370

Fig , p.371

Fig , p.372

Fig , p.373

cuttlebone arm jaw tentacle radula siphon brain esophagus kidney stomach gill anusink sac heart accessory heart reproductive organ mantle

Fig , p.374 false coelom (unlined body cavity) intestine eggs in uterusgonad muscular body wall pharynx anus

Fig , p.374

Fig , p.375

Fig , p.376 chelicerae

Fig , p.377

Fig , p.379

Fig , p.380

Fig , p.381