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SAI International School
Subject - Biology, Class-VI
Topic- Adaptation in living organisms
Subtopic- Aquatic habitats
Module- 27
Lesson notes

ADAPTATION FOR AQUATIC HABITATS

Aquatic habitats are of two types-

1. Freshwater
• Example- ponds, lakes, and rivers.
• Animals found here - fishes, frogs, etc
• Plants found here - lilies, Vallisneria lotus, etc.
2. Marine water
• Example-seas and oceans.
• Animals found here - sharks, whales, dolphins, etc.
• Plants found here – seaweeds, algae, seagrass, etc.

ADAPTATIONS IN AQUATIC PLANTS:

Aquatic plants are also called hydrophytes.

They can be-

• Free-floating
• Partly submerged
• Fully submerged
ADAPTIVE FEATURES OF FREE-FLOATING AND PARTLY SUBMERGED
PLANTS-

Example- Lily, Lotus, Duckweed, Lemna, Wolffia, Eichornia

• Roots -
▪ Poorly develop or completely absent.
▪ Lotus and water lily are called partly submerged as they are rooted
in the water body.
• Leaves
▪ Tough and can withstand the movement of water.
▪ Covered with cuticle to prevent the accumulation of water over
them.
▪ Stomata are found on the upper surface of the leaves and help in
the exchange of gases.
▪ Chlorophyll is found on the upper part of the leaf and helps in the
absorption of sunlight for photosynthesis.
• Stem
▪ Long and narrow and offers the least resistance to the flow of
water.
▪ They are hollow and have a lot of air spaces to provide buoyancy to
the plant.