There are seven life processes that tell us that animals are alive. To help us remember them we have found a friend to remind you – Mrs Nerg. Although her name sounds a bit strange, the letters in it stand for the life processes – movement, reproduction, sensitivity, nutrition, excretion, respiration and growth.
It’s a simple fact, most animals move. Humans (like you) can move because your body is supported by an internal skeleton – that’s right, you are just a bag of bones!
All vertebrate animals (fish, amphibians, reptiles, birds and mammals) have internal skeletons. Although they look quite different at first glance, they share some basic characteristics.
Animals can live happily all their lives, growing, eating and moving around, but if they don’t reproduce (make babies) they won’t have anything to show for themselves in the future – their species will quickly die out.
All animals reproduce. Human babies develop within their mother for nine months before they are born. They grow into children, adolescents, and eventually, adults.
Your senses let you know what is going on in the world around you. Humans have five senses: hearing, sight, smell, touch and taste. They are controlled by five sense organs: the ears, eyes, nose, skin and tongue.
Animals rely on some senses more than others. Hunting animals, like the cheetah, need very good eyesight to find their prey. Nocturnal animals often have very large eyes to maximise the amount they see at night, but also rely heavily on their sense of hearing.
Nutrition is just a complicated word for something we all like doing – eating!
All animals, including humans, eat to live.They take in food at their mouths, munch it with their teeth, and the teeth break it down so it can be taken into the stomach. All the nutritious bits of the food are absorbed into the body through the intestine, and the rest comes out the other end!
Chewing is very important – it starts the process that breaks down our food. Most mammals have teeth to chew their food. Their teeth are adapted to their diets, but they usually have some combination of the three types of teeth that are found in human mouths: incisors, canines and molars.
Excretion cleans up after respiration.
Respiration is a chemical reaction that takes glucose (sugar) and oxygen to produce energy. But it also produces water and carbon dioxide as bi-products.
Excretion gets rid of carbon dioxide, water, and other, possibly harmful, substances from your body.
Your lungs excrete carbon dioxide as you breathe out, your kidneys filter out nasties to produce urine, removing nitrogen waste from your body, and your skin sheds excess salt through sweat.
All animals respire. A lot of people think respiration means breathing – this is not true. Respiration is a chemical reaction. It occurs in every cell in your body.
Get a better view of the cell
So what is respiration?
During normal human respiration, glucose (a type of sugar that you get from food) reacts with oxygen to produce energy. The energy is needed for growth, repair and movement. Water and carbon dioxide are bi-products of respiration – they need to be excreted.
All vertebrate animals that live on land have lungs. When we breathe in, the muscle below the rib cage (called the diaphragm) is pulled down, and air gets sucked into the rib cage, filling the lungs. Blood cells circulating through tiny blood vessels near the lungs pick up oxygen and carry it around the body to the sites of respiration. Air is then forced out of the lungs as the diaphragm bows upwards.
Babies can’t stay babies all their lives!
They have to grow up! When first born, human babies are completely dependent on their parents for everything – food, water, shelter, clothing.
As babies grow into children and adolescents, humans are still dependent on their parents for many things – they have a lot of growing up to do, and don’t become independent until they reach the age of about 18 when they go to college or move away from home.