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Page 23

Most bony fish have two sets of paired fins: the pectoral fins, which are typically located just behind the gills; and the pelvic fins, found on the fish's belly below the pectoral fins. There are also three vertical fins: the dorsal fin, which is on the fish's back (some fish have front and rear dorsal fins); the anal fin, which is at the rear of the belly, and the caudal fin, which is the tail. Fins provide mobility and balance.

Fish must take in oxygen from the water and eliminate carbon dioxide from their circulatory systems. This is performed via the gills, which bring the fish's blood supply in close contact with the water. Bony fish have four pairs of gills, which are located on either side of the fish just behind the head. A fish breathes by closing the gill slits and opening its mouth, taking in water. The water is then forced through the gill chambers, over feather-like gill filaments that absorb oxygen from the water and remove carbon dioxide from the blood. The water is then passed out through the opened gill slits.

The skin of a fish is covered with a thin layer of slime, which performs a number of vital functions. First, the slime serves to protect the fish from parasites and disease. Second, it allows the fish to move easily through the water (which is why some long-distance swimmers coat their bodies with grease before a competition). Third, the slime prevents water from entering the fish's body.

Beneath the slime on most bony fishes are scales, which serve as another form of protection. Scales are layered in rows on the fish's body, much like shingles on a roof. One edge of each scale is attached to the skin of the fish. Scales are not living tissue, somewhat resembling fingernails. Some fish species have no scales; some have tiny, practically invisible scales; and some have large ones. People who eat large-scaled fish like perch with the skin on, such as when baking, should remove the scales before cooking. This can be done with a scaler, which resembles a dull-edged, large-sawtoothed knife. (See Chapter 27 for more information on fish cleaning and preparation.)

The lateral line on a fish is a long, thin canal that runs horizontally on each side of the fish's body, from just behind the gills to the base of the tail. On some fish it is also continued on the head and may have numerous branches off the main line. The lateral line is filled with sensory organs with which the fish is able to detect low-frequency sounds and changes in temperature, pressure, and water current. Fish also possess an inner ear, and numerous pits on the skin containing nerve endings detect touch. All this makes for a very vibrationsensitive creature.

Fish Recipes

Fish Recipes

This is a great collection of delicious fish and shell fish recipes that you will love.

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