Aquatic Habitats 

The important aquatic habitats are -

1. Oceans: Many sea-animals have streamlined bodies to help them move in sea water easily. 

2. Ponds, lakes and rivers: Ponds, lakes and rivers are “freshwater” aquatic habitats. The plants which grow in water are called aquatic plants.

1.0Types of aquatic habitat

There are three types of aquatic plants (or water plants). These are described below :

(a) Some aquatic plants float on the surface of water. e.g. water lettuce and water hyacinth.

(b) Some aquatic plants are partly submerged in water. The roots are fixed in the soil below water at the bottom of a pond, lake or river. The stems of such plants grow up to the surface of water while the leaves and flowers float on the surface of water. e.g. water lily and lotus.

(c) Some aquatic plants are completely submerged in water. The roots of submerged plants are also fixed in the soil below water at the bottom of a pond, lake or river. All the parts of such plants (including stem, branches and leaves) grow under water. e.g. Hydrilla and Vallisneria.

2.0Adaptations in aquatic plants (or water plants):

The aquatic plants show a number of adaptations. Some of the adaptations are as follows :

(a) The aquatic plants have very short and small roots whose main function is to hold the plant in place. All the parts of an aquatic plant are surrounded by water, so an aquatic plant can absorb water and dissolved minerals directly from the surface of their stems, branches and leaves.

(b) The stems of aquatic plants are soft, hollow and light, having large spaces filled with air. The aquatic plants do not need strong stems because the surrounding water of a pond, lake or river keeps them up.

(c) The submerged aquatic plants have narrow and thin ribbon-like leaves which can bend in the flowing water of rivers and streams and hence do not obstruct the flow of water.

3.0How is the frog adapted to live in water and on land?

Frog- like frogs have ponds as their habitat. Frogs can live inside water as well as on land near the pond. 

(i) Frogs have strong back legs for leaping (jumping) and catching their prey. This adaptation helps the frogs to live life on land.   

(ii) Frogs have webbed back feet which help them to swim in water. This adaptation helps the frogs to live life in water.

• Some sea-animals like squids and octopus do not have streamlined body shape. But when squids and octopuses move in sea-water, they make their body shape streamlined. Such animals stay deeper in the ocean near the sea-bed and catch any prey that moves towards them.

Dolphins and whales breathe in air through blowholes when they swim near the surface of water. After breathing in air, they close the blowholes with flaps and dive into the sea. Dolphins and whales can stay inside water for a long time without breathing.

4.0Migration

Birds, mammals, many types of fishes and insects show a unique phenomenon of migration. It involves mass movement of birds and animals from one place to another in response to a seasonal change.

• Birds, mammals, and many types of fishes show migration. These animals move (or migrate) to warmer regions when winter sets in. The animals come back after the winter is over. For example, Siberian cranes come from Siberia to places like Bharatpur (in Rajasthan) and Sultanpur (in Haryana). Another example is that of a European swallow, this bird is found in Northern Europe in summer but in winters it is found in Southern Africa and in India.

• Arctic birds such as the ptarmigans have feathers up to their feet, to keep their body warm. These ptarmigans stay in the Arctic throughout the year whereas some birds such as snow geese and Arctic terns migrate to warmer regions during the winter and return only after summer begins to settle in.

Note: R, S → Torrid zone → largest thermal zone.

Q, T → Temperate zone.

P, U → Frigid zone.

• Pangolins have an armored shell as outer body covering for the protection. It has the ability to curl into a ball when threatened.

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