Outline the adaptations fish have acquired to maintain their position in saltwater. What will be an ideal response?
The density of fish tissue is typically greater than that of the surrounding water, so fishes will
sink unless their weight is offset by propulsive forces or by buoyant gas- or fat-filled
bladders. Cartilaginous fishes have no swim bladders and must work continuously to
maintain their position in the water column. Sharks generate lift with a high tail and fins that
act like airplane wings. Their lighter cartilaginous skeletons and large, oily livers also help to
reduce their overall density. In contrast, bony fishes that appear to hover motionless in the
water usually have well-developed swim bladders just below their spinal columns. The
volume of gas in these structures provides enough buoyancy to offset the animal’s weight.
The quantity of gas is controlled by secretion and absorption of gas from the blood, and by
muscular contraction of the swim bladder to compensate for temporary changes in depth.
You might also like to view...
Alluvial fans form best in humid climates
Indicate whether the statement is true or false
Underground tanks were regulated under the:
a. Safe Drinking Water Act b. Resource Conservation and Recovery Act c. Clean Water Act d. Comprehensive Environmental Response, Compensation, and Liability Act
The 1993 flood in the central United States was caused by ________.
A. a single large rainstorm over a large area B. a series of dam failures after an earthquake C. several storms building up excess moisture over several months over much of the Upper Mississippi River Drainage Basin D. rapid melting of record winter snows during the springÂ
The driest desert in the world is the ________
A) Sahara B) Gobi C) Atacama D) Kalahari E) Simpson