Animal Strategies For Survival

         Scientists have described and named over a million different species of animals, every one of which is unique in details of both its physical structure and its behavior. Some living in the same area may overlap in their use of a shared environment. In times of hardship, however, such as food shortage in winter or dry seasons, or the stress of breeding and rearing young, each has its own way of coping that excludes all others. The first stratagem for survival is specialization. Each animal in its own niche is an unassailable specialist. Should the environment change the specialist may lose out, but in stable habitats the specialist is the winner.

Fruits

A true fruit is derived solely from the carpel or carpels of a flower after pollination. Some fruits are juicy, but many others are dry when they are ripe and they split open to release their seeds. Pea and bean pods are examples although we eat some of them before they are ripe. Botanists split juicy fruits into several groups. Berries generally have many seed embedded in the soft flesh. Grapes, gooseberries and citrus fruits are familiar examples.
The fruit and vegetables that we eat contain starch, sugar and other foodstuffs that the plants have stored up for their own use. Botanically speaking, fruits are formed from the pollinated flowers of plants. They always contain seeds. The term vegetable is generally used in amore loose way, often simply referring to plants eaten with the main course of the meal. This can cause some confusion. Cucumbers, marrows, peppers and tomatoes are commonly considered vegetables, although to the botanist they are in fact fruits.
Almost juicy fruits are rich in sugar and therefore quite sweet when they are ripe. Some also store starch and oils. These food reserves are not consumed by the plants themselves, but serve to attract animals that eat the flesh and scatter the seed. Most commercial fruits are obtained from trees and shrubs, although some important one, such as strawberries and pineapples, come from herbaceous plants. A few fruits are still gathered mainly from the wild, but the majority is now cultivated in plantations or orchards and, as with the vegetables, many are now larger and tastier than their ancestral forms.

Nuts

Botanically speaking, a nut is a dry fruit containing a single seed and having a hard, woody outer coat. Hazelnuts and sweet chestnuts are true nuts, and so are cashews and macadamia nuts, but in fact most of the other “nuts” that we buy in the shops are not nuts at all. They are mostly the inner parts of other kinds of fruits.

Walnuts, pecans and almonds, for example, are the equivalents of peach or plum stones, and until they fall from the trees they are enclosed in tough, leathery cases that correspond to the flesh of the peach or plum. Even the hard shelled coconuts are also the inner parts of the fruit, although here the outer part is thick and fibrous – it is used for coconut matting. Brazil nuts are actually hard shelled seeds that are obtained from ball shaped woody fruits.

Ground nuts or peanuts are the seeds of a leguminous plant, carried in pods. In all these examples, the parts that we actually eat are the seeds or kernels- the embryonic next generation of plants and their food reserves.

Unusual Adaptation

Flowering plants have evolved in many directions, becoming adapted to a wide range of habitats and acquiring many life styles. Plants growing on high mountains or on the northern tundra usually form mats or cushions close to the ground to escape the violent winds. The dwarf willow Salix herbacea, for example is a true willow, but it has underground stems and its aerial branches are rarely more than 3cm above the ground. The leaves and flowers of many mountain plants are darker than those of their low land relatives; dark colours absorb heat more efficiently in the cold climate.

Many plants manage to live in deserts despite the scarcity of water. Some of them are quick growing annuals that complete their life cycles in a short time and are not affected by the drought, but the typical desert plants store water through the dry season. Waxy or hairy coatings, and breathing pores sunk in deep grooves ensure that evaporation is cut to minimum. Many of the plants have very small leaves or none at all, although some species sprout leaves when the rains come and then drop them for the dry season.

Cacti nearly all grow in the American deserts and can survive prolonged drought. They have no proper leaves and their ribbed grooves store all their food. Wide spreading roots catch nearly all the rain that falls in the wet season and the stems swell up as they take up water. The stems shrink as they use up water in the dry season, and the grooves become deeper. The breathing pores in the grooves thus become better protected from the dry air. Spines protect the cacti from grazing animals seeking moisture.

Mosses, Ferns and Conifers

Mosses

Mosses and the closely related liverworts carry spores in stalked capsules. The capsules form only after the union of male and female sex cells. As in ferns the cells need moist condition so mosses flourish mainly in damp environment.

Ferns

Ferns generally carry their spores in little capsules under the leaves. The related horsetails carry their in fleshy cones at the tips of the stems. Although the reproductive process needs water, mature ferns can survive in dry places.

Conifers

Conifers bear sees on the scales of their cones. The cones are small and soft at first, but swell and become woody after pollination. When the seeds are ripe the cones either open slightly or fall to pieces to release them. Conifers are the best known of the cone bearing plants, known as gymnosperms.

The Plants

With something in the region of 300000 different kinds or species, plants make up one of the two great kingdoms of the living world. The chlorophyll they contain is responsible for the essentially green nature of the planet. Unlike animals, plants can manufacture their own food from simple inorganic materials mainly water and the carbon dioxide gas in the air, they are thus the primary producers of food and all terrestrial animal life depends on them, either directly or indirectly, for food.
Most animals stop growing when they reach maturity and each species has a fixed shape. But plants go on growing throughout their lives and although the leaves and flowers of a particular species generally have a fixed shape, the overall shape and size of the plant can vary a good deal according to its situation.

Leaving aside the flowers or other reproductive organs, a typical plant has three main regions – root, stem and leaf. The root anchors the plant and absorbs water and dissolved minerals from the soil by means of osmosis. Growth takes place by elongation of the cells just behind the tip and this forces the root down. Delicate root hairs just behind the growing regions absorb the water and pass it to tubes in the centre of the root.
The stem which may be soft or woody carries water and dissolved minerals from the roots to the leaves through a ring of tubes. Another set of tubes carries manufactured food down from the leaves and distribute it around the plant. The stem also arranges the leaves in the most efficient way for catching sunlight and in flowering plants, displays the flowers in the best position for achieving pollination. The leaves are the plant’s food factories. They are usually flat and have a number of veins. Continues with the tubes in the stems, the veins carry water to the leaf tissues for photosynthesis and also carry away the manufactured food. The undersides of the leaves have thousands of microscopic breathing pores that allow carbon dioxide in and oxygen out. They also release a lot of water vapor by evapo-transpiration.

Truffles, Gills and Pores, Lichens

Truffles

Truffles are subterranean fungi with solid, globular fruiting bodies. They grow mainly in broad leaved woods. The perigord truffle of southern France is a much prized and very expensive delicacy. The traditional way of finding truffles is to train pigs or dogs to sniff them out. Most attempts at cultivating truffles commercially have failed.

Gills and Pores

The typical mushroom gets its food from decaying matter in the ground. Its fruiting body is spherical when it first bursts through the soil, but it quickly expands to form a cap and stalk. The latter, often called the stipe, may have a ring showing where the rim of the cap was originally attached and there may be a cup or volva, at the base. Under the cap, most species bear numerous fragile gills arranged like spokes in a wheel. The gill surfaces release millions of spores, the equivalent of seeds in flowering plants. Other mushrooms looks more like sponges, scattering their seeds from thousands of minute pores.

Lichens

Lichens are among the hardiest of all organisms, growing in some of the hottest and coldest places. They clothe much of the arctic tundra. Each of the many species is actually a combination of a fungus and an alga. The alga can exist along, but the fungus cannot, so lichens are regarded as special kinds of fungi that rely on algae to provide much of their food.