Habitats and adaptation of organisms to their habitats.

What is a habitat?

A habitat is a particular place where a specie lives and reproduces is its habitat. The habitat might be the forest floor, a swift stream, or the ocean’s edge.

An ecological niche is the role a species plays in its community, including its habitat and its interactions with other organisms. The niche includes the resources used to meet energy, nutrient, and survival demands.

There are two main types of natural habitats;  

• Aquatic habitat.
• Terrestrial habitat

Aquatic Habitat.

Aquatic habitats are classified into two types: freshwater (inland) or saltwater as well as brackish water which is a mixture of fresh and salt water.

Examples of aquatic habitats are ponds, lakes, streams and rivers, oceans, and seas.

Freshwater Habitat.

Lake and Pond

Lakes are bodies of fresh water often classified by their nutrient status.

Oligotrophic (nutrient-poor) lakes are characterized by a small amount of organic matter and low productivity. Their low productivity keeps the water crystal clear, making them popular recreational sites.

Eutrophic (nutrient-rich) lakes are characterized by plentiful organic matter and high productivity. Eutrophic lakes are often thick and “soupy” making them unattractive for recreation. Over long periods of time, as sediments accumulate, lakes naturally change from oligotrophic to eutrophic; their basins eventually fill with sediments, and terrestrial plants invade.

Oligotrophic lakes can become eutrophic through large inputs of nutrients. This process is called eutrophication.

Lake/pond may contain species with relative population sizes. It has three zones within which organisms occupy.

• Littoral zone: it is a shallow region where sunlight penetrates to the bottom. It is occupied by rooted plants, water boatman, plankton, microscopic algae, larvae, duckweed, etc.
• Benthic zone: this part is towards the bottom. This zone is beyond sunlight penetration. It is occupied by fish, shrimp, water fleas, etc.
• Muddy zone/bottom: it is an area where the water meets the ground. It is occupied by water snails, water lilies, leeches, dragonfly nymphs, etc.

The zones may also be classified as littoral zone, limnetic zone, and profundal zone

• limnetic zone forms the sunlit body of the lake, small fishes, such as minnows and killifish,
• profundal zone is below the level of light penetration. E.g., catfish, whitefish, Crayfishes, and molluscs (see art).

Adaptations of organisms to live in ponds and lake 

• Vacuoles containing gas in many blue-green bacteria and oil stored in diatom enable these organisms to float on the water surface
• Some have large air space in their roots and leaves which support them float on the surface of water e.g., Pistia and Lemna
• Pond and lake plants have stomata only on the upper surface of the leaves and their cuticles are either waxy or covered with hairs to discourage water from blocking the stomata
• Some insects here have springtails and water-repelling bristles that enable them to stay on water surface e.g., Gerris (Pond skaters)
• Presence of spiracles and siphons for gaseous exchange e.g., pond skaters, mosquito larvae, and pupae respectively
• Some pond and lake plants have finely divided, thin leaves with no roots enabling them to float freely on surfaces of water e.g., Ceratophyllum
• Some have roots to the shallow bottom of the water and their leaves are long, flat, and thin giving them a larger surface area for maximum absorption of carbon (iv) oxide, and oxygen
• Presence of gills and swim bladder in some animals for breathing and being able to rest at any depth in water e.g., tilapia, Clarias (catfish)

Streams and rivers

Water is constantly moving and very often, conditions keep on changing e.g., when water falls heavily, the nutrients is been washed into streams and rivers and they also flow faster and turbidity also increases.

• Organisms living in streams and rivers tend being carried away by water currents.
• Organisms in streams and rivers either swim or adapt to this challenge.
• Some hide among the vegetation at the river bank where the water moves slowly. E.g., limpets
• Others attach themselves to the rocks and stones inside the water bodies e.g., the larva of blackfly.

Adaptations of plants to freshwater habitat (hydrophytes)

• they have large air spaces in leaves, stems for floating or buoyancy
• stomata on the upper surface of leaves for gaseous exchange
• waxy upper cuticle for repelling water droplets
• flowers are raised above the water surface for pollination
• leaves with a large surface area for maximum light absorption
• possession of soft or flexible stem of submerged plants which withstands the water currents
• Long petiole to support and expose the broad lamina for photosynthesis
• small size of plant for buoyancy
• submerged plants have thin cuticles permeable to water and mineral salts. e.g., water lily, elodea, lemna, Pistia, water lettuce,

Structural features which adapt animals to aquatic life

• Possession of gills/respiratory trumpet for gaseous exchange
• Presence of swim bladder for buoyancy
• Streamlined body for easy movement
• Lateral line for detection of vibration
• Fins/swimmerets/webbed digits for movement
• Suckers/hairs for attachment onto vegetation to prevent being swept away

Brackish Water

• Its salinity is between that of fresh water and sea water e.g., lagoon and estuarine
• Tide level fluctuate
• Organisms living in brackish water can tolerate variations in concentration of their body fluids e.g., crabs, bivalves, mudskipper, mangrove plant etc.

Marine 

• Marine consist of oceans and
• It has a high salinity
• Organisms that live in marine environment can tolerate a high concentration of salt e.g., herrings and tuna

it has three zones; land, intertidal zone and the sea

• intertidal zone is the zone between the water mark at low tide and high tide. some organisms that dwell at the intertidal zone include limpets, ghost crabs, mussels, barnacles, algae (sea lettuce and Sargassum).

Adaptations of organisms to seashore life (marine)

• some of the organisms has the ability to dig into the sand and others withdraw into their holes to avoid predation e.g., starfish (Astropecten), molluscs(Terebra, Donax)
• some avoid drying up by withdrawing into protective shell and enclosing some water with them e.g., limpets and barnacles
• some use their foot to attach to rocks by suction, others secret cemented elements for attachment e.g., limpets and barnacles
• crabs have flattened bodies that allow them to move into rock crevices
• some have holdfast for attachment onto rocks permanently e.g., green sea lettuce Ulva and brown algae Dictyopteris and Sargassum.

Terrestrial habitat 

• terrestrial habitats are categorized according to the type of vegetation
• It is categorized into forest, grasslands (savanna) and deserts
• The distribution of animals in these habitats depend on the kind of vegetation

Rain forest

• in a tropical rainforest, rain falls all year round
• the most abundant plants in a rain forest are trees
• Other smaller plants include, seedlings of trees, shrubs, herbs and ferns.

Epiphytes are also found in rainforests

(Epiphytes are plants that grow on and supported by other plants without taking any food nutrients from the other plant. Climbing plants are also found in a rain forest)

• the branches and leave of the tall trees form a canopy
• the canopy provides shade for other organisms’ examples of animals living in rain forests are tortoise, snakes (vipers), dulker, mice, rats etc.
• some animals live in the trees and are referred to as arboreal, e.g., grasshoppers, butterflies, ants, spiders, tree frogs, chameleons, snakes (green mamba), parrots, owl, bats, monkeys etc.

Adaptations of trees in the tropical rain forest

• trees have broad leaves to enhance water loss through transpiration
• trees have thin and smooth barks which facilitate water loss through transpiration
• trees have buttress roots to provide extra support
• trees are tall and unbranched to compete for adequate sunlight
• tree leaves have drip tips for water loss through transpiration

Adaptations of animals in tropical rain forest

• animals have opposable digits for climbing and grasping
• animals have tail for extra support when climbing
• some animals have grasping scales for climbing
• animals have sharp claws for climbing
• presence of patagium for gliding on trees. E.g., bats
• presence of expanded ribs for climbing
• exhibits binocular vision for judging distances accurately

Savanna

Savanna is mainly grassland, having smaller trees and shrubs.

The savanna experiences little rainfall all year round

In west Africa, the savanna is divided into three

• Guinea savanna – relatively humid
• Sudan savanna – less humid
• Sahel savanna – relatively dry

There is an increase in drought (decrease in rainfall) as you move from one zone to another (south to north)

• Plants found in this habitat are mostly annuals and perennials. Annuals are plants that complete their life cycle in one growing season (from germination to death) e.g., maize, rice, sunflower etc. whilst perennials are plants that continue to grow for several years, producing fruits and seed in most seasons. e.g., Terminalia, Acacia, Shear nut Most savanna plants are fire resistant
• Most savanna animals are herbivores and a few are carnivores e.g., mice, squirrels, antelopes, giraffes, zebras, elephants, monkeys, lions and cheetahs
• Others feed on carcass e.g., hyenas and vultures
• Birds like pigeons, cattle egret, insects like grasshoppers and termites, reptiles like cobra, lizards and chameleons all live in savannas

Structural features of animals for adaptation to terrestrial habitat

• Dry scaly skin/thick skin/cuticles to reduce water loss and prevent injury
• Possession of hairs/feathers for temperature regulation
• Lungs for gaseous exchange
• Sweat glands in mammals for cooling/excretion.

Desert

Desert is a terrestrial habitat that experience long periods of drought. It is also characterized by wind, low humidity and high temperature  

• Deserts are noted for extremely hot days and extremely cold nights.
• Organisms that survive in deserts are those that are adapted for water storage e.g., cactus, euphorbia, camels etc.

Adaptations of plants to dry terrestrial habitats (xerophytes)

• They have deep seated roots (taproot) for tapping water from the soil
• Succulent leaves or stem for water storage
• Modified leaves into spines or scales-like structure for reduction in water loss
• Presence of thick waxy cuticle or hairs on leave to reduce water loss
• Rolling of leaves or sunken stomata to reduce water loss
• Thick bark for fire resistance
• Plants with life cycle to survive unfavourable conditions
• Seasonal shedding of leaves to reduce water loss e.g., Cactus, Euphorbia, Acacia, Baobab, Bryophyllum, Casuarina, Aloe

Adaptations of animals to desert life

• Small mammals burrow to avoid extreme heat
• Some are active in the morning and evening to avoid extreme heat within the day e.g., reptiles,
• Production of concentrated urine to conserve water within the body
• Developed structures (humps) to store fats that can be metabolized to provide energy/food and oval blood cells for water conservation e.g., camel.

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