The adaptations which help fish to swim in water is
(a) presence of gills
(b) presence of scales
(c) air sacs
(d) Nictating membrane
Answers
Answer:
presence of gills a)
Explanation:
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Explanation:
Fish are aquatic vertebrates. They make up more than half of all vertebrate species. They are especially important in the study of vertebrate evolution because several important vertebrate traits evolved in fish. Fish show great diversity in body size. They range in length from about 8 millimeters (0.3 inches) to 16 meters (about 53 feet). Most are ectothermic and covered with scales. Scales protect fish from predators and parasites and reduce friction with the water. Multiple, overlapping scales provide a flexible covering that allows fish to move easily while swimming.
Adaptations for Water
Many structures in fish are adaptations for their aquatic lifestyle. Several are described below and shown in Figure below.
Fish have gills that allow them to “breathe” oxygen in water. Water enters the mouth, passes over the gills, and exits the body through a special opening. Gills absorb oxygen from the water as it passes over them.
Fish have a stream-lined body. They are typically long and narrow, which reduces water resistance when they swim.
Most fish have several fins for swimming. They use some of their fins to propel themselves through the water and others to steer the body as they swim.
Fish have a system of muscles for movement. Muscle contractions ripple through the body in waves from head to tail. The contractions whip the tail fin against the water to propel the fish through the water.
Most fish have a swim bladder. This is a balloon-like internal organ that contains gas. By changing the amount of gas in the bladder, a fish can move up or down through the water column.