​Producers to Consumers

• ​Animals drink and eat food to obtain the matter and energy they need for their life processes. Some organisms, such as plants, can make their own food. An organism that makes its own food is called a producer. Plants are able to use the energy from sunlight to produce sugars, which are a source of energy and matter. 

​Producers to Consumers

• ​On the other hand, an animal cannot make its own food. An animal is a consumer, an organism that obtains energy and matter by feeding (or consuming) on other organisms. Animals are consumers and get what they need from the environment.

​Producers to Consumers

• ​While animals take in matter from the environment, they also release wasters into the environment. Wastes are produced when matter is converted into materials that are not used by the body. Some wastes are form the breakdown of food. Others may be by-products from life processes. Wastes are then released into the environment.

• ​For example, carbon dioxide gas is a waste product released when an animal breathes out. Animals also eliminate the remains of digested food out of the body as waste.

​To Grow Anew

​Some animals can regenerate, or regrow, body parts. Regenerating body parts requires energy and matter. Food is important to an animal not only for growth but also for body repair.

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​Although only a few animals animals have the ability to regrow limbs, all animals perform body repair. Body repair can be as simple as producing substances to help a cut heal or as complex as repairing a broken leg.

​To Grow Anew

• ​Using the graph, find the average rate of regrowth of a sea star's arm. Is this average rate a good indicator of its arm length after 4 months?

​To Grow Anew

​Not really; the average rate is about 4 mm per month. If we used this 4mm times 5 months would be 20 mm, but the graph shows around 80 mm for 5 months.

Question Time!​

​Turn to your partner and talk about at least two reasons why animals need food to live, and explain your answers.