Diversity in the Living World

Opening

There is an old saying that a tree stands in the sun and makes shade for others, and that its fruit is also for others. Good people, the saying claims, are a little like that. Hold the picture, then walk outside. The first science in this journey is not a definition. It is attention.

A morning after rain is a good classroom. Birds are not making one sound. Each kind has a call of its own. Grasses, bushes, and tall trees are not one green smear. Butterflies work the flowers. A monkey takes a road through branches that your feet will never use. Diversity is what you notice when you stop treating "nature" as a single word.

Biodiversity, and how to look

Biodiversity is the variety of living things in a place, and on the whole Earth. It includes plants, animals, and the smaller lives you may not see on a short walk. It is not only a count of kinds. It is also the variety of shapes, foods, calls, and ways of living.

Looking has manners. You observe without tearing, chasing, or pocketing a life so you can "study" it later. A notebook, a pencil, and a water bottle are enough. Record the place, the stem, the leaf, the flower if there is one, what an animal seemed to eat, and how it moved. Two students on the same path will not write the same page. That is not a mistake. It is two pairs of eyes.

PauseIf every bird of a kind shares a call, what might a changed call, or a missing call, be trying to tell you about a place?

Grouping plants

Grouping means arranging things by features they share, so your mind can hold them. The group is not tattooed on the plant. You choose the feature, and the groups follow.

One useful grouping looks at height and the stem.

Herbs are short plants with soft, green, tender stems. Mint and coriander sit comfortably here.

Shrubs are medium plants with a harder, woody stem, and branches that begin close to the ground. A rose bush is the picture many gardens already know.

Trees are tall, with a hard woody trunk, and branches that typically begin higher up. A mango tree or a neem tree is the picture.

The same plant can be talked about in other ways: by the shape of the leaf, by the flower, by whether people eat it. A grouping is a question. Change the question and the bundles change.

Veins, roots, and the seed's secret

Look through a leaf at the light. The lines are veins. This pattern is called venation.

In reticulate venation the veins make a net. A hibiscus leaf or a mango leaf shows it.

In parallel venation the veins run alongside each other, like lanes. Many grasses, and the leaf of maize, show it.

Now the root. A taproot is one main root going down, with smaller roots leaving it. Mustard and a gram plant show this. A fibrous root is a cluster of thin roots, none of them a single boss. Grass is the everyday teacher.

Here is the pattern this class asks you to trust, and then to test.

Plants with reticulate venation usually have a taproot. Plants with parallel venation usually have fibrous roots.

The seed tells a matching story. A cotyledon is a seed leaf, a store of food for the baby plant. In a dicot seed, such as gram or bean, you can often split the seed into two cotyledons. In a monocot seed, such as maize, wheat, or rice, there is one. Dicots tend to travel with taproots and net-like veins. Monocots tend to travel with fibrous roots and parallel veins.

Grouping animals, and the places they fit

Animals can be grouped by where they live, what they eat, how they move, and what the body is covered with.

Terrestrial animals live mainly on land. Aquatic animals live in water. Amphibians, such as a frog, live a life that needs both. The word itself carries the double home.

Movement shows the place. Fins push water. Wings push air. Legs push ground. Webbed feet push both. A pigeon and a crow both fly, and they are still not the same bird. Food, call, nest, and beak keep the groups honest.

A habitat is the surroundings where a living thing finds what it needs. An adaptation is a feature that fits that habitat. Fit is not a compliment. It is a match that helps survival.

A cactus in a hot desert stores water in a fleshy stem. Its leaves are spines, which lose less water and discourage a bite. Its roots often travel far to catch a brief rain.

A deodar in a snowy mountain often grows with sloping branches, so snow slides instead of snapping the tree.

Camels are not one sentence. A camel of the hot desert loses little water, and its waste is small and concentrated. A camel of a cold desert carries a thicker coat and a different body for a different winter. The hump is a store of fat, not a tank of water. That correction is worth keeping.

Rhododendrons change their build with the mountain. Higher up, where wind and cold are sharper, the plants are often shorter, with smaller leaves. Lower down, where the weather is kinder, they can grow taller. Same kind of plant, different pressure from the place.

People who paid attention, and forests that were guarded

Janaki Ammal was an Indian botanist who looked deep into the cells of plants, worked on crops such as sugarcane, and spent her learning on the variety of India's plant life. She is a reminder that diversity is not only admired. It is studied, counted, and defended.

Salim Ali walked India listening to birds, until the country knew him as the birdman. Sanctuaries and serious bird study in India owe him a debt. A chirp, remember, is not background noise. It is a name said in another language.

Some forests were protected long before modern laws, by the community itself. Sacred groves are patches of forest, small or large, left undisturbed. They hold plants and animals, including medicinal plants. People agree not to cut and not to harm. Kerala, the Western Ghats, and many other regions have their own names and rules for such groves. Ask at home what the local name is. That question is part of the science.

The Silent Valley story, from Kerala, is a success worth knowing in outline. A forest of extraordinary life was going to be drowned by a dam. People, including scientists and local voices, argued that some treasures cannot be replaced by electricity alone. The forest stayed. Protection is a decision, not a mood.

We protect biodiversity because a planet full of one kind of thing is a planet that breaks easily. Variety gives living communities more ways to go on.