It's interesting how the fish sleep ?

You will need:
  • aquarium fish
  • observation
  • attention
# 1

Fish - it's water vertebrates.They can inhabit any body of water: in salt and fresh water in the ocean basins and small mountain streams.Breathe they gills throughout the development.Their length varies between seven and a half millimeters to twenty meters.Scientists know of about 30 thousand species of fish around the world.In Russia, it is found about three thousand different fish, of which only three hundred - fresh waters.

# 2

Fish - being incomprehensible to people not just because all life live in the water, but their dispensation varies widely with mammals.How is their basic processes of life - a puzzle that can be solved to man only by close observation.For example, the easiest way to see how the fish are sleeping - is to go at night in the room with an aquarium and turn on the light.Most individuals are usually located in the immovable state on the bottom or algae.So they sleep.But sleep in the human sense, it is imp

ossible to call.Rather, it is the state of low activity.

# 3

And fish eyes - open, because they do not have eyelids.Yes it this detail is not needed, since moisturize fish eyes - no.They and all the time in the water.Adult fish in the aquarium - all of the same size, but, for sure, they vary year.How to determine the age of fish?This can be done on the bones and scales.Because to see the bone, it is necessary to dissect the fish, the aquarium is best done on the scales.Each year of life corresponds to the ring on the scales, well visible to the naked eye.

# 4

And the fish are able to sniff.For this they have four nostrils divided into pairs.One bit in front, the second - a little behind.As the smell of fish with them?The front pair of nostril is flowing water, special sensory receptors tell the fish and the smell, then - the water comes out through the rear pair.Smell the fish developed strongly.They may even feel a very faint odor.Use it fishes well.For example, sturgeon, returning to spawn, find their way home only "on the nose".

# 5

expression "it like a fish" is not quite correspond to reality, since many species emit a variety of sounds.They say fish?The sounds are produced as a result of fluctuations of the swim bladder, and their nature is very diverse.It can be: clucking, quacking, knock, Twitter, croaking, purring, squeaking, and so on.Most "talkativeness" of fish observed in the mating season.

# 6

When the fish are sleeping, their eyes are open.They are watching everything and always on the alert: always ready for action.How to see the fish with his round, unblinking eyes?Their eyes - a sophisticated optical instrument.On your device it resembles a camera.The lens - a lens, the retina - the film.In order to view the object in the far distance (in the clear water - up to 15 meters), special muscles move the lens.Therefore, everything that happens in the room, where there is an aquarium fish, see, react and can wake up, if you go signal of possible danger.