Day: December 8, 2009

This is a diagram of a food web. Almost all animals must eat other organisms to obtain energy. Animals do not generally eat just one thing, nor are they eaten by only one thing. This means that each organism, through feeding, is interconnected to many different organisms. A food web shows how all species in a community are connected.

Let’s think about the organisms in an environment. If any one species is disturbed, then all species will undergo changes in its population. Eg. If small fish numbers go down then snail and cockle numbers will go up. Big fish and seabird numbers will go down.

An animal can be both a predator and a prey. For example, a small fish may eat certain types of snails, but he may also be eaten by a duck. So the small fish is both predator and prey in this food web..

Almost all animals must eat other organisms to obtain energy. Animals do not generally eat just one thing, nor are they eaten by only one thing. This means that each organism, through feeding, is interconnected to many different organisms. A food web shows how all species in a community are connected.

We, humans, often upset the balance of different populations in natural ecosystems, or change the environment so that some species find it difficult to survive. We reduce the amount of land available for animals and plants by: building; quarrying; farming; dumping waste.

Our activities may pollute: water ‐ with sewage, fertiliser or toxic chemicals; air ‐ with smoke and gases such as sulfur dioxide; land ‐ with toxic chemicals, such as pesticides and herbicides, which may be washed from land into water.

Ecology is the study of organisms and their relationship with their surroundings. Ecologists study the interaction between an organism and its environment. Some ecologists study a specific species or habitat. They might study the behaviour of a single species to see how it interacts with other organisms and the environment. Or, an ecologist might study many different species that either depend on each other (a food web, for example), or compete with each other for food and space

Every organism needs to obtain energy in order to live. For example,plants get , energy from the sun, some animals eat plants, and some animals eat other animals.

A food chain is the sequence of who eats whom in a biological community (an ecosystem) to obtain nutrition.

• The arrows indicate the direction of energy flow.
• The food chain moves food from one organism to another, giving energy to the organism digesting the food.

Eg. Buttercup → Bee → Thrush → Hawk. Plankton → Herrings → Salmon →Seals → Killer whales

• All food chains start with the sun which provides energy for plants.
• Photosynthesis by plants converts light energy to food. Plants are considered producers because they make their own food.
• The producers above are grass, buttercup, rosebush and plankton.
• Animals, including humans, cannot make their own food. As a result, they must get their energy from other sources, usually plants and other animals. Thus, animals are considered consumers.

As you can see in the diagram, food chain is the sequence of who eats whom in a biological community (an ecosystem) to obtain nutrition. Every organism needs to obtain energy in order to live. For example, plants get energy from the sun, some animals eat plants, and some animals eat other animals.