Posts tagged ‘Fish’

Do fish drink the water they live in?


Fish consume the water they inhabit if it agrees with their system.  Since the bodies of freshwater fish are much saltier than the water they live in, they don’t drink.

They are in danger of too much water entering their bodies, diluting their body fluids. They urinate often to get rid of any extra water that soaks into their bodies.

Saltwater fish, however, drink large amounts of water, since the salty sea water absorbs moisture from their bodies, causing dehydration.  These fish eliminate excess salt through their gills and very concentrated urine.–Dick Rogers

How can fish breathe in water?

Fish breathe with gills, which are inside the fish’s head on each side of its throat.  The gills are made of a thin material that allows the fish’s blood to come close to the surface of the gills.  Water contains large amounts of oxygen.

When a fish breathes, it takes a mouthful of water, and then closes its mouth.  This forces the water pass the gills.  The oxygen in the water is absorbed through the think surfaces of the gills, and into the fish’s blood.  The water then leaves the fish’s body through narrow gill slits on each side of its heard.–Dick Rogers

Can fish drown?

Fish can drown under certain conditions.  It is not the water that keeps fish alive, but the oxygen in the water.  Fish breathe oxygen, just as we do.  The water contains oxygen that comes from the air or is given off by water plants.

A fish takes the oxygen out of the water by means of its gills.  When a fish is placed in a small tank of water, however, it may soon use up all the oxygen that is in the water.

If this happens, the fish suffocates.  This is why, if you keep pet fish, you must change the water frequently in order to give them a fresh supply of oxygen.–Dick Rogers

Do fish have ears?


Yes, fish have ears and can hear.  But most fish hear very poorly.  You cannot see a fish’s ears because they are buried deep inside its head.  In addition, many kinds of fish also have tiny sense organs arranged in lines along the sides of their bodies which are called the lateral lines.

This organ feels vibrations in the water.  It lets the fish know what’s going on around it, even if it does not see or hear anything.  Through its lateral line organ, a fish can sense the vibrations of your footsteps along the banks of a stream and swim away. –Dick Rogers

Do fish sleep?


Yes, fish sleep.  Because fish have no eyelids, they cannot close their eyes—and it may look as though they never sleep.  Many fish sleep by simply remaining very still in the water.

Others lie on the bottom, resting upright or on their sides.  And a few others wriggle into the sand on the floor of the body of water in which they live.

In this way, fish rest their bodies as you and I do when we sleep.  If you happen to see a fish lying almost motionless in the water, it is probably asleep.  Fish don’t sleep as soundly as humans do, and the slightest disturbance will wake them.–Dick Rogers

What is a called blooded animal?

Cold Blooded Animal

Many animals such as fish, frogs, snakes and lizards are often called “cold-blooded,” as opposed to “warm-blooded” mammals and birds.

This does not mean their blood is always cold. Unlike warm-blooded animals, they do not have built-in temperature controls that keep their bodies evenly warmed.

Instead, their body temperature is usually near that of the surrounding air or water air or water.  The cold-blooded animal is hot in hot weather, and cold in cold weather.

Many depend on the sun for their body heat. Lizards, for example bask in the sun to warm their bodies.–Dick Rogers

Why fish don’t sink?


A fish, with its bones and scales, is heavier than the water it displaces. Under normal circumstances, it would tend to sink.  But most bony fishes have a balloon-like sac inside their bodies called an “air bladder” that acts as a float to keep them from sinking.  The air bladder fills up with some of the oxygen dissolved in the fish’s blood.

Some fish, such as pike and catfish gulp air at the surface of the water to fill their air bladders.  A shark has no air bladder to buoy it up.  It must constantly be swimming in order to keep from sinking. – Dick Rogers

Why do fish swim in schools?

School of Fish

Some fish swim alone; others stay in groups known as “schools” or “shoals.”  A school of fish swims in formation, moving and turning with great precision.  The old saying that there is safety in numbers can be observed here.  Not only are many eyes better than one in watching for enemies, but when threatened, a school of fish scatters in all directions.

Since the predator must choose which fish, to pursue, usually only one fish is likely to be caught—a small price to pay for the survival of the group.  Schooling also insures reproduction and eases the task of food gathering. – Dick Rogers

How does a fish swim?


A fish pushes itself through the water by curving its body from side to side and swishing its powerful tail fin.  The other fins help it to keep its balance and help guide it, and for braking.

Most fish have swim bladders filed with air inside their bodies.  The swim bladder acts as a float so that the fish can lie quietly in the water without rising or sinking.

A fish can control its depth in the water in much the same way a submarine varies its depth.

To go down, a fish lets some of the air out of its swim bladder.  To go up, it forces more air into it.

Fish called “darters” have no swim bladders. They have to flap their chest fins to keep afloat in the water.  Nature has shaped the fish so that it scarcely disturb the water as it swims.

Man, seeing  how easily and swiftly fist cut the water, patterned his boats and submarines after a fish’s streamlined body. – Dick Rogers