Adaptation of Desert Animals

21, May, 2023 0 Comments

Adaptation of Desert animals

Describe desert’s fauna adaptations in brief.

Desert animals are adapted to conserve moisture and escape heat of shimmering sun. They fall into following two categories:-

(a) Drought Evaders –

Drought evader xerocoles, like ephemeral plants, adopt an annual life style or go into cultivation or some other stage of dormancy. For eight or nine months, perhaps even several years, the eggs of insects and other invertebrates and insect pupae lie dormant. When the rain arrive and plants flourish, the deserts swarm with insects – crickets, grasshoppers, ants, bees, wasps, butterflies, moths, beetles, etc. going bear emerge from underground cells at the very time when the particular flowers

on which they feed are in flower. Some amphibians like spade foot toads aestivate for eight or nine months in an underground cell lined with a gelatinous substance that reduces evaporative losses through the skin. They appear on ground when the rain fall saturates the earth, move to the nearest puddle, mate and lay eggs. Young tadpoles hatch in 1% to 2 days, rapidly mature (15 to 45 days) and metamorphose into functioning adults capable of diging, their own retreats in which they aestivate until the next rainy season.

Birds nest during the rainy season, when food is most abundant for the young. If extreme drought develops during the breeding season, some birds do not reproduce. Keast (1959) has reported that among some. desert birds the endocrine control of reproduction depends on rainfall rather than day length. A few birds such as swifts, poorwills and humming birds become torpid when food is scarce small rodents such as kangaroo or pocket mice, aestivate during periods of most severe drought.

(b) Drought Resisters –

Drought resisters xerocoles are active whole year round and have evolved way of circumventing aridity and heat through morpho-physiological adaptations or by modifying their feeding and activity patterns (i.e. behavioural adaptations). Some animals simply avoid the heat by adopting nocturnal habits and remaining underground or in the shade during the day. Some desert rodents that are active by day periodically seek burrows and passively lose heat through conduction by pressing their bodies against the burrow walls. Some birds such as poor wills and humming birds and bats go into a daily torpor.

The large ears of some desert animals such as jackrabbits and kit fox may serves to reduce the need of water evaporation to regulate body heat. The ears may function as efficient radiators to the cooler desert sky, which on clear days may have a radiation temperature of 25°C below that of the animal. By seeking shade, where the ground temperature are relatively low and solar radiation is screened out, and sitting in depressions, where radiation from the hot ground surface is obstructed, the Lepus could radiate 5 kcal a day through its two large ears (400cm2). Such a radiation heat loss minimizes the heat loss through water evaporation (sweat glands).

The Kangaroo rat, which seals its burrow by day and thus keeps its chamber moist, can live throughout year without drinking water. Similar adaptation occurs in the jerboas and gerbils of Africa and the Middle East and the marsupial Kangaroo mice and Pitchipitchi of Australia. These animals feed on dry seeds and dry plant material even when succulent green plants are available. The kangaroo rat obtains water from its own metabolic process and from hygroscopic water in its food. To conserve water the animal remains in its burrow, by day, it possesses no sweat glands, its urine is highly concentrated and its faces is also dry.

Large desert animals such as the camel can use water effectively for evaporative cooling through the skin and respiratory system because their low surface-area-to body size ratio and lower internal heat production result in slower accumulation of heat. The camel not only excretes highly concentrated urine but can with- stand dehydration upto 25 per cent of body weight, and it loses water from body tissues rather than from blood. The camel accumulates its fat in the hump rather then over the body. This speeds heat flow away from the body and its thick coat prevents the flow of heat inward toward the body.

IMPORTANT LINK

Disclaimer: quizsansar.com does not own this book, PDF Materials Images, neither created nor scanned. The material and information contained on this website is for general information purposes only. If you have a complaint about something or find your content is being used incorrectly then kindly mail us: sansarquiz@gmail.com

quiz sansar