Fish Anatomy Index Cards

Fish Anatomy Index Cards - The head, abdomen and tail form...

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The head, abdomen and tail form one continuous unit (no neck). The head extends from the tip of the snout to the posterior edge of the operculum (gill cover), the abdomen extends back to the anus , and the tail includes everything posterior to the anus, including the caudal fin . (Remember the postanal tail , a chordate character.) Most of the body is covered with scales, which are thin plates of bone. The scales overlap, and the posterior exposed part of each bears tiny tooth-like projections making these ctenoid scales. Notice the lateral line , a sensory system on the side of the body, which consists of microscopic sense organs in a tube that extends through a long row of scales back to the tail. Pores (holes) in the tube convey stimuli from changes in water pressure to the sense organs. A similar system is present on the head. The body bears fins consisting of a thin membrane of skin supported by bony fin rays. Some of these are soft rays ( lepidotrichia ) made up of articulated segments of bone derived from scales, while others are spines (actinotrichia). The median, unpaired fins are the spinous (anterior) dorsal fin (supported by actinotrichia), soft (posterior) dorsal fin (supported by lepidotrichia), caudal fin , and anal fin . The shape of the caudal fin is referred to as homocercal , meaning that the upper and lower lobes are about equal in size. The paired fins are the pectoral fins and pelvic fins. Note that most of the fins have a spine on their leading edge Most of the muscle mass of the body is made up of the paired, segmental myomeres , which are folded and nested as in the other chordates you have examined. However, the folding is more complex here, and the myomeres are divided into dorsal (epaxial ) and ventral (hypaxial ) regions, separated by a connective tissue layer, the horizontal septum (not shown in figures).
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Inside the terminal mouth is the oral cavity
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This note was uploaded on 03/13/2008 for the course ZOO 201L taught by Professor Staff during the Winter '08 term at Cal Poly Pomona.

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Fish Anatomy Index Cards - The head, abdomen and tail form...

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