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fish-characteristics - swim by undulating movements of...

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Characteristics of fish 1 eye nostril lateral line spines dorsal fin tail fin ventral fin anus pelvic fin (reduced to a spine operculum mouth 3-spined stickleback - a small fresh-water fish inhabiting ponds and streams Fish are vertebrates - i.e. they have a vertebral column. In most cases their bodies are covered with overlapping scales. Although they are often called ‘cold-blooded’ their temperature varies with that of their surroundings. Tropical fish will have warmer blood than fish in the North Sea. They reproduce by laying eggs which are usually fertilised externally, i.e. the male releases sperm over them as they escape from the body of the female. Some species have internal fertilisation where sperms are introduced into the female’s body. Fish breathe by passing a current of water over their gills. Many fish have a ‘streamlined’ shape which allows relatively rapid movement through the water. Most fish
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Unformatted text preview: swim by undulating movements of their body Mouth - takes in food and allows a stream of water over the gills. Nostril - a blindly ending sac with organs of smell. Dorsal and ventral fins - reduce rolling motion during swimming and help in turning movements Tail fin - imparts final thrust in swimming movements Operculum - covers and protects gills and lets water escape from them Lateral line - a tube running the length of the body just below the skin. It is filled with a jelly like liquid and has sensory nerve endings. It is a sense organ which responds to changes in pressure, e.g. movements in the water nerve jelly-filled tube sensory nerve endings openings to surface body wall © D.G. Mackean pectoral fin pectoral and pelvic fins - help to steer and stabilise fish Lateral line...
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