Water life

1. Water Life

2. Water
• 1. WATER:
• Water is one of the factors which makes life possible on Earth. Water covers 71% of the
Earth's surface. It is vital for all known forms of life. 96.5% of the planet's water is in form
of seas and oceans. Sea water surrounds lands, and freshwater flows inland.

3. Characteristics of water
• freshwater:
low mineral content;
used by people to drink and for economic purposes;
vital for plants and animals;
natural habitat for plants and animals.
• salt water:
high mineral content, especially salts;
it’s not suitable for direct consumption by people;
natural habitat for plants and animals.

4. Types of surface waters
• freshwater:
still water: swamp, lake, pond;
flowing water: river, stream.
• saline water:
a sea;
an ocean.

5. • Under the surface of the Earth there is groundwater which is fed by rainwater.
• Water source is a natural water outflow on the surface which gives origin to streams and
rivers.
• Lakes are the natural bodies of water of standing water. They are formed in depressed
areas and are fed by water sources or rivers.

6. Animals
Animals which natural habitat is near water can be divided into three groups:
• Living near bodies of water (land animals): they get food from water, their nests are on
land, their eggs hatch on land.
• semiaquatic: they freely move in water, here are their hiding places, here they procreate;
they can also stay on land.
• aquatic: they live only in water, they are not able to stay on land for long.

7. Fish
• Fish - A fish is any member of a paraphyletic group of organisms that consist of all gill-
bearing aquatic craniate animals that lack limbs with digits.
Structure of fish
• The scales function is a protection of fish. They are like a kind of body armor that
significantly reduces the possibility of injury and makes it more difficult to be attacked by
animal ectoparasites. In addition, fish scales help in overcoming the resistance of water
by reducing friction.

8. Fins
Fish fins are the most distinctive features of a fish, composed of bony spines protruding from the
body with skin covering them and joining them together. They perform different functions:
• steering
• maintain body balance
• Allow swimming back and forth
• Allow maintaining fish' altitude in water
• Allow the correct position of the body

9. Body shape
Fish have a great variety of body shapes owing to natural habitat or lifestyle they lead. Most
of the fish living in schools or fast-flowing water have a streamlined body shape such as a
tuna. While the still water of lakes with rich bottom-level vegetation is inhabited by fish with
laterally flattened body such as a bream or a roach. They are not persistent and fast
swimmers, but very they're reflexive. The demersal fish, characterized by the flattening of
the body, are e.g. flounders.

10. Fish

11. Amphibians - are ectothermic, tetrapod vertebrates of the class Amphibia. They have thin skin without scales.
To live in water
• mucus moistening skin
• streamlined body shape,
• webbing between the digits,
• triangular head rigidly connected to the backbone,
• beltline in tailed amphibians,
• External fertilization and development in water;
To life on land
• construction of the extremities,
• lungs.
• atmospheric oxygen intake,
• gas exchange through the skin.
• lacrimal gland moisturizing eyes,
• the inner ear to receive sounds.

12. Frog