HABITATS: INTRODUCTION, TYPES, MAJOR ZONES, CHARACTERISTICS

Habitats are natural places in our environment. These habitats play important roles in contributing to the wellness of plants, animals, organisms living in them and eventually man. There are different habitats known to man and they are Aquatic habitats, Terrestrial habitats, Grassland or Savannah, and Arid land.

AQUATIC HABITAT
The aquatic habitats include marine, estuarine, and fresh water.

MARINE HABITAT
This is concerned with the organisms living in water. These organisms possess an interrelationship that helps different organism living in them to co-habituate. There are different characteristics of the marine habitats that makes them possible. These characteristics are outlined below;

1. Salinity of sea water: These waters contains many dissolved ions, e.g. sodium, potassium, calcium etc. The salinity of sea water is high and also increases during the dry season due to evaporation.

2. Density of Sea Water: This is about 1.028 and this helps organisms to float with ease.

3. Temperature: This falls with increase in the depth of the sea.

4. Light Penetration: Light penetrates into the sea only to a maximum depth of 200m.

5. Oxygen Concentration: This is highest at the surface of the water which is in contact with atmospheric oxygen.

6. Hydrogen Ion Concentration: The pH of sea water is about 8.0 to 8.5 near the surface hence making it alkaline.

7. Waves, Ocean Currents and Tides: These improves transparency, air circulation, nutrients and temperature in water.

MAJOR ZONES OF THE MARINE HABITAT
Zones in a marine habitat are:
1. Splash or supra tidal zone.
2. Neritic or intertidal or planktonic or euphotic zone.
3. Littoral or subtidal or diphotic (disphotic) zone.
4. Lenthic or oceanic zone.
5. Pelagic or abyssal zone and
6. Hadal or aphotic zone.

CHARACTERISTICS OF MARINE ZONES
These are given below;
a. Splash Zone: the splash zone is above the high tide. It is exposed and also has occasional moisture as a result of constant prey from breaking waves.
b. Intertidal Zone: this zone is exposed at low tide or covered by water at high tide. It has high photosynthetic activity, abundant light and fluctuating water temperature.
c. Littoral Zone: this zone is constantly under water. It has high abundant light and enough nutrients.
d. Benthic Zone: this zone has low light penetration or low light intensity.
e. Pelagic or abyssal Zone: this zone has low temperature, high pressure, low photosynthetic activity through chemosynthesis.
f. Hadal Zone: there is no light penetration and no photosynthetic activities in this zone.

DISTRIBUTION OF ORGANISMS IN THE MARINE HABITAT
Splash Zone: Sand- crab and ghost-crab.
Inter tidal Zone: Starfish, anemones, sponges, sea urchins, clam, annelids, molluscs, and barnacles.

Subtidal Zone: Snails, Crabs, Lobsters, and crayfish.

Bathyal and Abyssal Zones: these are unfavourable for life.

Neritic Zone: Plankton, nekton and fish.

Oceanic Zone: Shark, Croaker, Sea cat-fish, mackerel and moon fish.

ADAPTATIONS OF PLANTS IN MARINE ZONES
These adaptations are given below;

SEA WEED
1. It has hold-fast for attachment.
2. It has mucilaginous cover to prevent desiccation.
3. It has divided leaves or floating devices or air bladder for buoyancy.

ALGAE E.G. SARGASSUM
1. Sargassum has chloroplast or chlorophyll for high photosynthetic activity.
2. It has small size or large surface area for drifting or floating in water.

ADAPTATIONS OF ANIMALS IN MARINE ZONES
Marine animals show some adaptations to survive in the habitat, some of these adaptations are given below;

Barnacles
1. They have basal disc for attachment.
2. They have cilia which are used for feeding.
3. They have shell that prevents desiccation or drying up.
4. They have mantle which retains water.

CARTILAGINOUS FISHES
These kind of fishes have reduced or no kidneys to retain little urea in the body to cope with the salinity of water.

BONY FISHES
1. They have reduced or no kidneys and so drink sea water to cope with salinity.
2. Bony fishes have salt secreting glands in their gills or eyes for maintaining osmoregulation or salt balance.

WHALE
1. Whale has fins for stability in water.
2. Whales has melon which is the organ in front of the nostril to detect pressure changes in water.
3. Whale has a thick layer of dermal fat or bladder for heat insulation or food reservoir.

ESTUARINE HABITAT (MANGROVE SWAMP)
Characteristics of the habitat are as follows;
1. A fluctuating salinity.
2. Saturated soil that lacks oxygen.
3. Mild wave action.
4. High and low tidal influence
5. Soil erosion.

DISTRIBUTION OF ORGANISMS IN AN ESTUARY
PLANTS: Red and white mangrove plants, plankton and algae.

ADAPTATIONS OF ESTAURINE ORGANISMS
PLANTS
1. White mangroves have breathing roots to permit intake of atmospheric air and their leaves can excrete salts.
2. The red mangrove have stilt roots to enable it to withdraw strong ocean winds.
3. To ensure development of the seedlings and to avoid being swept off by ocean current, some seeds germinate on the parent plant.

ANIMALS
1. Crabs have air-breathing lung-like structures for breathing.
2. Starfish have tube feet to hold fast.
3. Shell-like covering in barnacles and starfish to protect them from drying up.
Food Chain Existing in the Habitat
Diatoms ———Small fish ——Shark ——-Man

THE FRESH WATER HABITAT
Characteristics of Fresh Water Habitats Include;
1. Low salt content.
2. Relatively small body of water.
3. Shallow water.
4. Variable temperature with depth and season.
5. Low density water.
6. Available oxygen in all parts of water but more at the surface.

TYPES OF FRESH WATER
1. STAGNANT WATER: Pools, pond, puddles and lakes.
2. RUNNING WATER: Springs, Streams and Rivers.

Areas or Zones in Fresh Water Habitat and Distribution of Organisms
In fresh water habitat, four major areas of zones are considered;
1. The edge of the water.
2. Water surface.
3. Body of water.
4. Bottom of water.

Edge of water or Littoral Zone
Characteristics;
1. The amount of water fluctuates.
2. Organisms in this area are covered with water during the rainy season but are exposed in the dry season.
3. There are optimal temperature, light intensity and wind action in this area.

The plants present in this area include grasses, raffia palm, algae, bamboos and sedges.

The animals present here are crab, water snails, dragon flies, water snakes, toads, frogs, mosquito larvae or pupae.

WATER SURFACE
They have the following characteristics
1. This area receives enough light, oxygen and nutrients.
2. Rainfall and wind action are optimum in this area.

The plants found in this area are water lettuce, duckweed, microscopic plankton, water hyacinth, etc.

The animals present in this zone are water scorpion, tadpoles, water bugs, and diving beetles etc. Most plants here are free floating.

BODY OF WATER (DEEPER CENTRAL ZONE)
They have the following characteristics
1. There is reduction in wind actions and amount of light in this area.
2. Carbon (IV) Oxide content in this area is high.
3. The oxygen content in this area is low.

The plants present in this area are submerged plants such as phytoplanktons (algae), and ceratophylum.

The animals found here are fishes, water snails, flatworms, mosquito pupae, insect larva, etc.

BOTTOM OF WATER
They have the following characteristics
1. Light intensity in this area is low
2. Darkness prevails all the time in this zone.
3. Carbon (IV) Oxide is higher while oxygen is very low in this area.
4. Due to absence of water currents, nutrients accumulates in this area.

Plants are scarce in this area but plants such as algae and bacteria may exist here.

Animals found here are insect larvae, fishes, molluscs, crabs, worms, etc.

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