The Vital Functions of Living Beings

To begin, we need to define what are these major or vital functions of living beings. Not all living beings are animals, but even the smallest cells need to fulfil their major functions or they will not be able to continue. In biology, vital functions are those processes living organism carry out in order to survive at least long enough to leave offspring. These functions are:

• Nutrition
• Interaction
• Reproduction

All animals will carry out these functions in some way or another. Individual cells will not eat like a human being, but they will need to fulfil these functions to continue. Our explanation of these basic functions will focus, however, on animal vital functions. Each individual species, and even individual animals within a species, may have peculiarities of how they perform these functions, but they all have the same purpose to live and reproduce.

In the function of nutrition, animals require energy to develop as they age and maintain their other basic functions. Animals are heterotrophic beings, meaning they cannot produce their own food source naturally. Instead, animals need other living organisms to obtain organic matter for sustenance and energy. But this function in animals does not end here. Digestion and assimilation of nutrients are the beginning stage, but once absorbed they do into the circulatory system. Here they deliver all the necessary forms of nutrition to the body's organs and cells.

These cells will then perform cellular respiration, converting these nutrients into energy. Everything the cells do not need returns to the circulatory system and then from there into the digestive system. Afterwards, the waste material is excreted. The two main forms are urination and defecation.

For these reasons, the nutritional function is not one singular function. Rather, it is compromised of various stages including:

• Food ingestion
• Digestion
• Cellular respiration
• Excretion

Even the above stages can be broken down into many complex actions. In terms of vital functions, however, they are a good overview. Animals need to carry out this nutrition function in tandem with breathing (whether through lungs or gills) to survive.

All animals must relate to their environment and the other beings within said environment. This includes members of their own species as well as those of others. If this does not happen and the animal is not aware of the environment around them and the changes which can occur, it will not survive. Animal interaction is also known as animal relation.

In the same vein, animals must relate to themselves and the changes which occur within them. This is why we can break down the major function of animal interaction into:

• External: these are the changes which occur outside of the body. There are all different kinds, from sounds and smells, to visualizing a predator which is trying to prey on them. For reproduction, which we will discuss further below, certain animals need to know if another of their species is in heat or are present. They may do this by sensing the changes in heat and light or by perceiving other types of stimuli.
• Internal: these are the changes or stimuli which come from inside the animal. These may be perceiving cold, heat, hunger, tiredness, etc. Much of these stimuli are considered to be part of their circadian rhythm or biological ‘clock’.

The previous vital functions are important for the survival of the individual organism. The function of reproduction, however, is not necessarily vital for the individual animal, but it is vital in some form for the continuation of the species. Doing so will pass on the genes after the individual animal has died. The two types of reproduction are sexual and asexual:

1. Sexual reproduction: this requires the presence of two cells, one ‘male’ and one ‘female’. Almost all forms of animal species reproduce sexually, requiring either female and male partners or, as in the case with snails, two hermaphrodite individuals to perform this vital function.
2. Asexual reproduction: does not require two individuals with different sexes to reproduce. In these instances a single organism is able to produce genetically similar offspring on their own.

In the animal kingdom, we can find various types of asexual reproduction:

• Budding: an animal which reproduces asexually might do so through the process of budding where it grows and generates an independent individual. Marine sponges and some jellyfish reproduce in this way.
• Fragmentation: part of the original animal is sectioned, separated and then grows independently to create a new being.
• Parthenogenesis: following an unfertilized germ cell, and under certain specific circumstances, an embryo can develop which produces a genetically identical animal to the mother. Some insects (including ants and bees), fish and reptiles can perform parthenogenesis. The offspring are all exclusively female as a male germ cell does not intervene.

If you want to read similar articles to The Vital Functions of Living Beings, we recommend you visit our Facts about the animal kingdom category.