Life is movement

When we peep out of the window, we may see birds chirping, flitting from a branch to another, a dog or a cat moving. We can see movement of ants, butterflies, and lizards not very far from home.

Movements fascinate us. A moving animal catches our eye. A bird absolutely immobile on a tree, is difficult to see even when some one is pointing it out to us. But the moment it moves we spot it.

Life is movement. Nearly all animals move from place to place (locomotion) and also move parts of body while lying, sitting at the same place. There are a few exceptions to this rule – adult sponges (phylum – porifera) never go from place to place. Their larvae do. Sponge larvae have a coat of cilia. They can swim with the help of cilia. Barnacles, a type of crustacean – arthropods – are attached to rocks and never locomote. So also, the protochordate, urochordate – herdmania (adult again larva is an active swimmer, predator). Herdmania is in the sea and so also the sponges and barnacles. Seawater has tidal movements and swirls. It brings food and oxygen and carries the waste away from the bodies of these animals.

But these animals are exceptions and generally all animals move. Some keep moving all the time. Like sharks that swim while sleeping or can swim while sleeping.

Just as, as a rule animals move, plants do not go from place to place i.e. locomote. Once again, there are exceptional cases like, Volvox, a colonial alga swims with its ciliary coat. Chlamydomonas, a green unicellular alga with two flagella and a green protist, Euglena with a flagellum can swim (and if we agree to consider them as plants) are plants which locomote. But there are very few such examples. Plants are rooted to the ground. However, their body parts can move. Flowers open and close. Tendrils curl around support. Fruits open – some of them explosively.

Bacteria, which are so tiny, can locomote with their flagella. Amoebae show their famous ‘amoeboid’ ambling way to go places.

Why do the all these diverse forms of life move?

“Money makes the mare go.” is a proverb explaining movement of people on such a large scale. Mumbai, a city where I stay, has a local rail transport system which helps move nearly half a million people from their homes to their work places. Like humans, animals too go in search of food. They try to avoid their predators / enemies. They seek warmth, shelter, water, mates, companions for playing / hunting and move they must if they have to find them. Parenting also makes animals go from place to place. A cat picking up her baby tenderly by the scrape of neck and shifting residences is a common sight. As also a bird bringing grubs for its mate and young ones.

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