CONTENT 

• Estuarine habitat
• Characteristics of estuarine habitat
• Plants and animals distribution in estuarine habitat

Plants’ Adaptation in Estuarine

Plants found in estuaries include planktons, algae, red and white mangrove. They have the following adaptive features; 

1. Planktons (diatoms) have; i. air spaces in their tissues ii. rhizoid for the attachment to rock shores iii. air bladder for buoyancy
2. Algae have: i. chlorophyll for photosynthesis ii. small size or large surface area for floating in water.
3. Red mangrove has; i. stilt roots with rootlets that have air-spaces for air conduction to the root tissues and support to prevent washing away of the plant by the tide ii. Seeds which germinate while they are still on the parent plant, thus preventing the carrying away of the seedlings by water current.
4. White mangrove has pneumatophores (breathing roots) for gaseous exchange.

Animal Adaptation 

Animals including mosquitoes, crustaceans, mollusks, worms, fishes e.t.c. found in estuaries ;survive possessing the following features;

1. Mosquito larvae and pupae possess breathing trumpets for gaseous exchange
2. Crustaceans and water snails burrow into the mud against predators, strong waves or tides.
3. Worms have strong protective and impermeable covering against high salinity.
4. Mudskippers have fins for crawling on land and swimming in water.
5. Fishes have fins for movement and swimming bladder for buoyancy.

Evaluation:

1. What is a fresh water habitat?
2. Mention five animals dwelling in estuary.

Plant Adaptation in Fresh Water 

Plants of fresh water include water lily, spirogyra, water lettuce, water weeds e.t.c. and they have the following adaptive features;

1. Water lily has i. air bladder ii. expanded tips and light weight which keep it afloat.
2. Spirogyra has mucillagenous cover for protection
3. Water lettuce has hairs in leaves to trap air and keep it afloat
4. Water weed (elodea) has a long and flexible petiole for swinging with water currents. 

Animal Adaptation 

Animals of fresh water habitats include protozoa, duck, pondskatters, hydra, fishes e.t.c. Their adaptive features include

1. Protozoa have contractile vacuole for osmoregulation in water.
2. Duck has webbed feet for locomotion and serrated beak for sieving food in water into its mouth. 
3. Hydra has slippery surface, hooks and suckers for attachment to water particles.
4. Pondskatters has long legs for skating on water surface.
5. Fishes have swim bladders for buoyancy and gills for respiration.

General Evaluation 

1. Using three plants and two animals, explain adaptation in marine habitats.
2. Give two examples of food chain in marine habitats.
3. Define an estuary.
4. State four characteristics of an estuary.
5. How do organisms adapt to life in estuary?

Weekend Assignment 

1. Buoyancy in salt water is ensured by the following except  A. divided leaves  B. chlorophyll  C. floating devices  D. air bladder.
2. The mucillagenous cover in seaweed and spirogyra is mainly for  A. protection  B. osmoregulation  C. avoiding dessication  D. feeding.
3. Which of the following is not a freshwater habitat?  A. puddle  B. swamp  C. stream  D. sea.
4. Which of these is not an adaptive feature in a marine habitat?  A. bladder for floating  B. hold fast for attachment  C. fur to prevent water loss  D. rhizoid for attachment to rocks.
5. The following are characteristics of fresh water habitats except  A. low salt content  B. high salinity  C. shallow water  D. can be stagnant or running water.

THEORY

1. List five characteristics of an estuary.
2. State five adaptive features of animals in a fresh water habitat and their functions.