We tend to think of insects and small animals as pests rather than assets. But these seemingly insignificant and often troublesome creatures play a silent and unseen but vastly significant role in ecology.

The term ecology was coined by combining two Greek words, “oikos” (meaning house or dwelling place) and “logos” (meaning the study of). Ecology is therefore the study of relationships between the organisms and their environment.

One of the five great laws of ecology reads, “There is no such thing as a free lunch”, which means that every organism serves the environment by some means or the other. This article deals with how small animals serve the environment. The biological process of eating and being eaten is an interesting aspect of ecology (the relationship / interaction of the biotic organisms with one another), about which, not much work has been done as yet.

The following are a few examples of small animals and their role in the food chain.

Role of ants

The interaction between ants and various parameters of the environment is not fully known. Owing to intense competition for food and space in tropical forests, interactions between some species of plants, animals and environment are more subtle and intricate than in other forests. Ants are perhaps the only single group of creatures that change the environment to a considerable extent. They are found everywhere: in the bark of trees, roots, branches, leaves, fruits and flowers. There are several species of ants and they are coloured red, black, brown and other colours.


Leaf-cutting ants are of immense importance and they live in the soil. The slimy secretion of ants is favorable to the growth of a fungus on which the young ones feed. The ants serve the plants in the vicinity of their nests by stripping them of the dead and yellowed leaves. They ingeniously solve the problem of garbage disposal by taking what they need for their consumption, deep into their underground homes. From ant to fungus to ant and back to tree root, the nutrients of the forests are used and recycled. This is an example of the efficient use of energy that helps to make tropical forests a stable ecosystem.

Ants are carnivores and feed on arthropods (spiders, grass-hoppers, crickets, cockroaches, etc.). More than 200 species of scavenger flies depend on army ants for their food supply.


The pollination activities of the honeybee are an indispensable aid to agriculture. This task is of even greater importance than its value as a producer of honey. In this respect, the honeybee can be considered as an agricultural catalyser, for numerous plants would fail to be perpetuated and many fruit and forage crops cannot be grown successfully without bees to fertilize the blossoms.

02Courtesy: Naim, M, Bee-Keeping for Pleasure and Profit, Kalyani Publishers, New Delhi, 1993.

Who eats who/what?



By their feeding activities millipedes and centipedes contribute to the breaking down of plant material and the formation of humus. Spiders have an important role to play in the natural world. It is ridiculous to kill or crush spiders without reason.

Earthworms burrow deep into the soil, creating tunnels and throwing up little circled piles of egested soil at the surface called “casts”, which are rich in nutrients.


In the forest, the squirrel finds plenty of food: young shoots in the spring, mushrooms and nuts in the autumn, snails, insects, bird’s eggs, etc.

04Courtesy: Hamlyn Junior Encyclopedia, The Octopus Publishing Group Limited, 1990.

When plenty of food is available, the squirrel begins to gather and store it by burying it underground. It does not always find it again in the winter. The seeds germinate in spring. So, thanks to its forgetfulness, the squirrel helps to plant new trees. This contribution to the life of the forest makes up a little for the damage the squirrel causes in spring by eating buds and young shoots.

Jayanthi Rengun
Blue Cross of India, Chennai

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