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Katha
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Bhagavad Gita

Chapter II - Wonder World Under Water II [ One-Celled Animals ] [This book has been distributed into different chapter for easier access. Picture shown - are not part of the book.]

Our body is made up of many organs, like the stomach, the liver, the heart, the brain, kidneys and lungs. In turn, these organs are made of tissues like fat, muscles, cartilage, and the tissues are made up of tiny, microscopic units called cells. Thousands of cells live together in our body, and perform their own functions; we are, therefore, multicellular organism. Animals, which first evolved on earth millions of years ago, were much more primitive, each consisting of only one cell.

One of the most primitive animals is Amoeba. The shape of its body is not constant, and the animal moves by extending a part of its body called the pseudopodium, meaning false foot forward, just as a drop of water moves on a smooth surface. If it comes across a food particle, these projections flow over it and engulf it. After the food is digested, the undigested wastes are thrown out of the body by the projections parting. When the animal wants to have young, it simply splits into two, and each part goes its own way. In some cases the animal collects bits and pieces of debris around itself and shapes them into the form of a “shell” or “test”. Other animals (e.g., Globigerina and Radiolaria) make their own shell by extracting lime or silica from seawater. Although these animals are barely visible to the naked eyes, when they die their skeletons sink to the ocean bottom, where their shells cover shapes are called “ooze”. The shells come in many pretty shapes and are a pleasure to see under a microscope.

In some members of this group (e.g., the sun animalcule Antinophyra sol), the pseudopodia form a symmetrical halo around the animal, resembling the rays of the sun.

A slightly more evolved group are the flagellates. The body is enclosed in a cell wall which is quite flexible, so that the animal can stretch or bend, but it cannot flow freely as does Amoeba. At one end of the body there is usually a single long whip-like hair, called the flagellum (sometimes there are two). These flagella enable the animal to move in the water. Some of these flagellates (e.g., Euglena) have the same green matter, called chlorophyll, which is found in the leaves of plants. With the help of this chlorophyll, Euglena, like plants, use the energy of sunlight, to manufacture their food. Botanists therefore claim that these green flagellates are plants but, because they can swim, zoologists say that they are animals! Some flagellates come close to one another to form a colony. Each animal  can live separately but prefers to be in the company of its brethren. An example is Volvox.

Some of these flagellate animals can be a nuisance and may even be dangerous. One form, when multiplies in larger numbers, give seawater a red color; hence it is known as “red-tide”. A fluid thrown out from its body is so poisonous that it kills fishes-the sea surface is sometimes covered by dead fish as  far as the eye can see. Another form produces light and, when millions of them float on the sea surface, the water appears to be on fire.

Other one celled animals, related to those which cause malaria in man (the mosquito is only the carrier of the parasite which causes malaria; the mosquito is not harmed by the parasite) cannot lead an independent existence but are parasites, attaching themselves to fishes and other animals, feeding on their body tissues or blood, and causing disease and death in the animals on or in which they live.

In the ciliates (e.g., slipper animalcule, Paramecium) the body is almost completely surrounded by short, hair-like “cilia”. These beat in unison, looking like grass in a field bending with the wind, and help the animal to swim.

Continue to Chapter III - Wonder World Under Water III [ Sponges ]