5 Written Questions

1. The deeply grooved structure in the floor of the pharynx. It contains both ciliated and glandular cells.
2. The supporting rod that extends almost the entire length of the body. The larger rounded structure that lies beneath the nerve cord. It is surrounded by a connective-tissue sheath.
3. Located on both sides of the epipharyngeal groove.
4. A very narrow cavity located inside the nerve cord.
5. The row of rectangular bulging masses located beneath the ventral ends of the myomeres. These are located ventrolaterally in most sections. They protrude into the atrium from the body wall, still bounded by the atrial lining. An ovary consists of many large nucleated cells. A testis consists of much smaller germ cells, which appear as tiny specks.

5 Matching Questions

1. Ocelli
2. Ventral fin
3. Caudal Fin
4. Ventral Coelomic Cavity
5. Transverse muscle

1. a Lies beneath the endostyle.
2. b A linear series of pigment cells lying along the ventral wall of the nerve cord. They may possibly serve as photoreceptors.
3. c An anterior continuation of the caudal fin extending to the atriopore. This fin is seen in cross sections of the intestine at levels posterior to the atriopore. At levels anterior to the atriopore, the metapleural folds, hepatic diverticulum, atrium, and dorsal aorta will be seen in its place.
4. d An expanded continuation of the median dorsal fin at the posterior end of the body. A short projection from the ventral mid-line region that is supported by the gelatinous fin rays. This is a narrower and highter than either the dorsal or ventral fins, and dorsal aorta.
5. e This lies in the wrinkled body wall between the metapleural folds. It extends from the myomeres on one side to those on the other. When it contracts, it compresses the atrial cavity dorsal to it from side to side, thus expelling its water.

5 Multiple Choice Questions

1. The cavity that surrounds the pharynx laterally and ventrally.
   1. Rostrum
   2. Atrium
   3. Atriopore
   4. Velum
2. The snout-like anterior end of the body that projects over the oral hood.
   1. Rostrum
   2. Atrium
   3. Velum
   4. Gonads
3. Located in the roof of the pharnx opposite the endostyle.
   1. Oral hood
   2. Pharynx
   3. Epipharyngeal groove
   4. Dorsal aortae
4. Short tender projections extending from the margin of the velum that rings the mouth. By bending across the mouth, they may prevent sand or particles from passing into it.
   1. Endostyle
   2. Dorsal aortae
   3. Vestibule
   4. Velar tentacles
5. The vertical membrane located just behind the base of the wheel organ. The velum may regulate the amount of water entering the pharynx.
   1. Ocelli
   2. Velum
   3. Rostrum
   4. Atrium

5 True/False Questions

1. Pharynx → The large cavity surrounding the pharynx. Its ventral boundary is visible as a line extending below the pharynx to the atriopore.

   True        False

2. Metapleural folds → A pair of integumentary folds that extend along the ventrolateral surfaces from the anterior pharyngeal region almost to the atriopore. These project down from the ventrolateral corners of the body.

   True        False

3. Buccal cirri → An expanded continuation of the median dorsal fin at the posterior end of the body. A short projection from the ventral mid-line region that is supported by the gelatinous fin rays. This is a narrower and highter than either the dorsal or ventral fins, and dorsal aorta.

   True        False

4. Myomeres → The longitudinal series of about 60 angularly shaped muscle segments, known also as myomtomes. Masses of muscle under the skin.

   True        False

5. Nerve cord → The elongated cylindrical mass of nervous tissue that lies above the notochord. It is almost as long as the notochord. The somewhat triangular structure located in the mid-line, slightly ventral to the dorsal fin.

   True        False