FIGURE 29.14
Anatomy of a planarian. The mouth is at the tip of a muscular pharynx that extends from the middle of the ventral side of the animal. Digestive juices are spiled onto prey, and the pharynx sucks small pieces of food into the gastrovascular cavity, where digestion continues. Digestion is completed within the cells lining the gastrovascular cavity, which has three branches, each with fine sub-branches that provide an extensive surface area. Undigested wastes are egested though the mouth. Located at the anterior end of the worm, near the main sources of sensory input, is a pair of ganglia, dense clusters of nerve of nerve cells. From the ganglia, a pair or ventral nerve cords runs the length of the body.
FIGURE 29.14Anatomy of a planarian. The mouth is at the tip of a muscular pharynx that extends from the middle of the ventral side of the animal. Digestive juices are spiled onto prey, and the pharynx sucks small pieces of food into the gastrovascular cavity, where digestion continues. Digestion is completed within the cells lining the gastrovascular cavity, which has three branches, each with fine sub-branches that provide an extensive surface area. Undigested wastes are egested though the mouth. Located at the anterior end of the worm, near the main sources of sensory input, is a pair of ganglia, dense clusters of nerve of nerve cells. From the ganglia, a pair or ventral nerve cords runs the length of the body.
การแปล กรุณารอสักครู่..
