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Nutrition in animals is equally essential as plant nutrition. Plants make their food through the process of photosynthesis, but animals cannot, hence they must rely on plants or other animals for food.
- Animals get nutrition either directly from plants (herbivores) or indirectly from animals that have eaten plants (carnivores).
- Omnivores are animals that eat both plants and other animals.
- All living things require nutrition to survive and grow.
- Food contains many nutrients such as carbohydrates, minerals, fats, proteins, and vitamins.
- All of which are necessary for the maintenance of the body.
- These components are complicated and cannot be used directly.
- Thus, they are broken down into simpler components during digestion.
| Table of Content |
Key Terms: Nutrition, Nutrients, Heterotrophic, Omnivorous, Carnivorous, Digestion, Assimilation, Photosynthesis, Minerals, Vitamins, Modes of nutrition, Assimilation
Nutrition in Animals
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The feeding habits of animals determine their nutritional status. The process of consuming food is known as ingestion.
- The mechanism of ingestion varies amongst animals.
- For example, Bees and hummingbirds suck nectar from plants, whereas pythons swallow their prey and cattle eat grass.
- Animal feeding habits have evolved throughout time.
- Among terrestrial animals, the earliest forms were large amphibians that consumed fish.
- While amphibians, such as frogs, ate small fish and insects, reptiles began to eat other animals and plants.
- One of the primary reasons for form and function evolution is organismal specialization toward certain food sources and, of course, unique feeding habits.
- For example, changes in the parts of the mouth and shape of the teeth in whales, mosquitos, tigers, and sharks, as well as various kinds of beaks in birds such as hawks, woodpeckers, pelicans, hummingbirds, and parrots, are the results of adaptation to different types of eating.
Animals can be categorized into the following groups based on their food habits:
Herbivores
Herbivores are animals that depend on plants and fruits for nutrition. Cows, goats, sheep, buffaloes, and other animals are herbivores.
Carnivores
Carnivores are animals that depend on other animals for nutrition. Carnivores include animals such as lions, tigers, and wolves.
Omnivores
These animals eat both plants and animals. Humans, bears, dogs, and crows are omnivorous.
Nutrition in Animals
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| Related Articles | ||
|---|---|---|
| Digestion in ruminants | Heterotrophic nutrition | Autotrophic nutrition |
| Nutrition in humans | Carnivores and herbivores | Nutrients |
Modes of Nutrition
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The two important modes of nutrition are
Autotrophic Nutrition
In this type of nutrition, plants and other photosynthetic organisms use sunlight, water, and carbon dioxide to produce their own food.
Heterotrophic Nutrition
Animals cannot make their own food. Therefore, they have to depend on other animals for nutrition. This is known as heterotrophic nutrition.
Types of Nutrition in Animals
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Different types of nutrition in animals are:
Filter Feeding
In this process, nutrients are acquired from particles suspended in the aqueous medium (like water). This method is commonly seen in fish.
Deposit Feeding
In this process, nutrients are obtained from particles present in the soil. e.g. Earthworms.
Fluid Feeding
In this process of obtaining nutrition one organism’s body fluids are consumed by another organism. Honey bees, mosquitos, and butterflies exhibit this type of feeding.
Bulk Feeding
Whole organisms are grabbed and eaten to obtain nutrients.
Ram Feeding and Suction Feeding
In this process, an organism is consumed to obtain nutrition via the fluids around the organism. Aquatic animals such as bony fish exhibit this.
Process of Nutrition in Animals
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The following are the processes of nutrition in animals
Ingestion
It is food intake into the mouth; i.e., the starting point of the alimentary canal.
Digestion
It is the breaking of ingested food into simpler substances. Digestion occurs through two processes: mechanical by chewing, grinding, mixing, and churning, and chemical by enzymes, bile, and acid.
Absorption
Digested food is absorbed in the small intestine into the blood vessels through finger-like structures, called villi.
Assimilation
Absorbed substances are transported to different organs of the body via blood vessels to build, grow, repair, etc.
Egestion
Elimination of undigested food through the anus is called egestion.
Nutrition in Simple Animals
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The nutrition in simple animals like amoebas is given below
Amoeba
- Amoeba eats microscopic organisms to obtain nutrition.
- It intakes food by pushing out pseudopodia around the food particle and engulfing it.
- Digestive juices are released into the food vacuole which breaks down the food into simpler substances.
- Digested food is absorbed by the cell and undigested food is expelled outside by the vacuole.
Types of Nutrients for Animals
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Different types of nutrients for animals are
- Carbohydrates: The basic source which provides energy for all animals. Animals obtain their carbohydrates by autotrophic nutrition.
- Lipids: Form cellular and organelle membranes, sheaths, and hormones. Some are useful energy sources.
- Nucleic acids: For the construction of deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and ATP. Animals obtain nucleic acids from tissues or cells that contain nuclei.
- Proteins: Proteins are essential components of the cytoplasm, membranes, and organelles. They are major components of enzymes, muscles, etc.
- Minerals: Animals require phosphorus, sulphur, potassium, magnesium, and zinc. Animals usually obtain these minerals by consuming plants.
- Vitamins: Organic compounds, in trace amounts for the health of animals.
Things to Remember
- Animal nutrition comprises food intake, mode of intake, digestion, egestion and utilization.
- The process of consuming food is known as ingestion.
- Omnivores are animals that eat both plants and other animals.
- Carnivores are animals that depend on other animals for nutrition.
- Herbivores are animals that depend on plants and fruits for nutrition.
- Two important modes of nutrition are Autotrophic Nutrition and Heterotrophic Nutrition.
- Digestion is the breaking of ingested food into simpler substances.
- Elimination of undigested food through the anus is called egestion.
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Sample Questions
Ques. What is nutrition? (1 Mark)
Ans. Nutrition is the process by which organisms ingest food and use the nutrients it contains.
Ques. What are nutrients? (1 Mark)
Ans. A nutrient is a substance that helps an organism live, develop, and reproduce. Animals, plants, fungi, and protists all require dietary nutrients.
Ques. Why is nutrition important for animals? (1 Mark)
Ans. Nutrition contributes to the proper development and maintenance of cells. It supplies energy to support many living processes.
Ques. What should we adopt to avoid tooth decay? (3 Marks)
Ans. Tooth decay can be avoided by the following measures.
(i) Rinse and clean its teeth, if possible, after every meal.
(ii) Clean our teeth with toothpaste and brush, twice a day.
(iii) Use dental floss (strong thread) to take out trapped food particles in between the teeth.
(iv) Dirty fingers or unhygienic objects must not be put in the mouth.
(v) Minimize consumption of sweets, chocolates, toffees, ice cream and cold drinks etc.
Ques. Explain how the digestion of cellulose occurs in grass-eating animals. (5 Marks)
Ans. Herbivorous animals such as cows, buffaloes, etc eat grass.
(a) They swallow grasses and store them in a part of the stomach called rumen.
(b) The food is not chewed completely. Rumen possesses cellulase (cellulose-digesting bacteria) which breaks down the food by fermentation.
(c) These partially digested grasses in the rumen of cows are known as cud.
(d) This cud is brought back into the mouth of the cow from the rumen and chewed again. This process is called rumination, giving these animals the name “ruminants”.
(e) Cud is chewed completely in the mouth of the cow and is swallowed again. Now the chewed cud does not go to the rumen but enters into the other compartments of the stomach and then into the small intestine for complete digestion and absorption of food.
(f) Cellulase are not present in the body of human beings, therefore human beings and other carnivores cannot digest cellulose present in plant food items.
Ques. Define tongue. What are its functions? (3 Marks)
Ans. The fleshy boneless muscular organ attached to the floor of the buccal cavity is called the tongue. It is free at the front and it can move in all directions.
The functions of the tongue are:
- mix saliva with food.
- help in swallowing the food.
- help in identifying the various tastes of different food materials
Ques. Differences between nutrition in Amoeba and human beings. (3 Marks)
Ans. The differences are:
| Digestion in Humans | Digestion in Amoeba |
|---|---|
| Humans have an alimentary canal and a complex digestive system. Humans ingest food through the mouth. | The alimentary canal is absent in Amoeba. It ingests food using pseudopodia. |
| Digestive juices are secreted in the alimentary canal: in the buccal cavity, stomach, and small intestine. | Digestive juices are released in the food vacuole. |
| Digestion of carbohydrates, proteins, and fats initiates in separate regions. | All the food components are digested simultaneously in the food vacuole. |
Ques. Why is it advisable not to eat in a hurry and talk or laugh while eating? (2 Marks)
Ans. It is said so because, within the human throat, air and food share a common passage. While talking, the valve of the windpipe opens and while swallowing food, it remains closed. But when we eat in a hurry and talk or laugh while eating, the valve of the windpipe remains open or does not close properly. This may lead food particles to enter the windpipe. It may cause choking or coughing.
Ques. What is diarrhoea? How is it caused? How can it be prevented? (2 Marks)
Ans. Diarrhoea is a disease, where there is frequent and watery bowel movement. It may be caused by infection food poisoning or indigestion. It can be fatal under severe conditions. Diarrhoea causes excessive loss of water and salts from the body and may cause dehydration.
It can be prevented by not eating stale food, maintaining hygiene while cooking or eating, being aware of the expiry dates of food, and not leaving food in the open.
Ques. What is the digestion process in amoeba? (4 Marks)
Ans. The digestion process is as follows:
- Amoeba eats microscopic organisms to obtain nutrition.
- It intakes food by pushing out pseudopodia around the food particle and engulfing it.
- Digestive juices are released into the food vacuole which breaks down the food into simpler substances.
- Digested food is absorbed by the cell and undigested food is expelled outside by the vacuole.
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