. Chordate morphology. Morphology (Animals); Chordata. anus (on left side) velum with languets cirri on oral hood hepatic diverticulum ^°"°'^ LtapleuraHold Ventral body wall Figure 1-5. Gross internal relationships in Amphioxus. distance behind the esophagus a diverticulum (blindly end- ing pouch) of the gut extends forward on the right side for about one-third of the length of the pharynx. This hepatic ("liver-like") diverticulum, carrying with it a pouch of the coelom, projects into the atrium. Behind the diverticulum the gut tapers toward the intestine, which leads to the anu
. Chordate morphology. Morphology (Animals); Chordata. anus (on left side) velum with languets cirri on oral hood hepatic diverticulum ^°"°'^ LtapleuraHold Ventral body wall Figure 1-5. Gross internal relationships in Amphioxus. distance behind the esophagus a diverticulum (blindly end- ing pouch) of the gut extends forward on the right side for about one-third of the length of the pharynx. This hepatic ("liver-like") diverticulum, carrying with it a pouch of the coelom, projects into the atrium. Behind the diverticulum the gut tapers toward the intestine, which leads to the anus near the posterior end of the animal. The anus opens to the left of the caudal fin, which is displaced to the right. The interior of the pharynx and the intestine is ciliated. The pharyngeal cilia drive a mucous net from the ventral endostyle or hypobranchial groove upward to the epibran- chial groove. Here the net is rolled up and driven back into the esophagus. In the gut the food materials are moved about by the cilia during the process of digestion. The excretory system consists of a series of segmental vesicles; into each of them opens a large number of soleno- cytes, excretory cells containing a flagellum (Figure 1-4 D,E). The vesicles open into the pharynx above the dorsal margin of the shts. In addition to these segmental "nephridia," there is a single tube extending forward to the right of the notochord from just above the mouth; this is the nephridium of Hatschek. In the ventrolateral angles of the pharyngeal region, there are about 26 pairs of gonads (reproductive organs) in the adult animal (Figure 1-4 F). These extend back to the atrial pore. The sex cells are shed into the atrium and carried to the exterior through the atrial pore. Each of the muscle segments lies in a connective tissue sheath. Near the notochord there is a small sclerocoel, a term applied to the fluid-filled cavities along the axis of the animal. The sclerocoels also enclose the ray
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