In Focus

Ocean life on the brink of mass extinctions

Life in the oceans is at imminent risk of the worst spate of extinctions in millions of years due to threats such as climate change and over-fishing, a study showed on June 21.Time was running short to counter hazards such as a collapse of coral reefs or a spread of low-oxygen "dead zones," according to the study led by the International Programme on the State of the Ocean (IPSO).

"We now face losing marine species and entire marine ecosystems, such as coral reefs, within a single generation," according to the study by 27 experts to be presented to the United Nations.

"Unless action is taken now, the consequences of our activities are at a high risk of causing, through the combined effects of climate change, over-exploitation, pollution and habitat loss, the next globally significant extinction event in the ocean," it said.

Scientists list five mass extinctions over 600 million years -- most recently when the dinosaurs vanished 65 million years ago, apparently after an asteroid struck. Among others, the Permian period abruptly ended 250 million years ago."The findings are shocking," Alex Rogers, scientific director of IPSO, wrote of the conclusions from a 2011 workshop of ocean experts staged by IPSO and the International Union for Conservation of Nature (IUCN) at Oxford University.

Fish are the main source of protein for a fifth of the world's population and the seas cycle oxygen and help absorb carbon dioxide, the main greenhouse gas from human activities.Jelle Bijma, of the Alfred Wegener Institute, said the seas faced a "deadly trio" of threats of higher temperatures, acidification and lack of oxygen, known as anoxia, that had featured in several past mass extinctions.

A build-up of carbon dioxide, blamed by the U.N. panel of climate scientists on human use of fossil fuels, is heating the planet. Absorbed into the oceans, it causes acidification, while run-off of fertilizers and pollution stokes (feeds) anoxia."From a geological point of view, mass extinctions happen overnight, but on human timescales we may not realise that we are in the middle of such an event," Bijma wrote.

The study said that over-fishing is the easiest for governments to reverse -- countering global warming means a shift from fossil fuels, for instance, toward cleaner energies such as wind and solar power.

"Unlike climate change, it can be directly, immediately and effectively tackled by policy change," said William Cheung of the University of East Anglia."Over-fishing is now estimated to account for over 60 per cent of the known local and global extinction of marine fishes," he wrote.

Courtesy :Reuters

Animal Kingdom

1.Who propounded the Theory of

Evolution and on what is it based?

2. From what kinds of animals

have birds evolved?

3. How does a bat sit on a tree?

4. How many kinds of lizards are there?

5. Do the lizards hibernate in winter?

6. How does a rattlesnake’s tail begin to rattle?

7. How do tortoises and turtles catch insects to feed on?

8. Up to what maximum length can a shark grow?

9, How would you distinguish an alligator from a crocodile?

10 How does a chameleon change its colour?

11. Can a fish hear,smell and taste?

12. What is the number of eggs that a female frog lays?

13.Which frog lays its eggs in a nest?

14.Why does a snake swing its body into curves or loops?

15. What are guineapigs?

[ Answers]

1. The Theory of Evolution, propounded by the English naturalist, Charles Darwin is based on the study of fossil remains, the distribution of animals and the study of embryology among many other areas.

2. Birds have evolved from reptiles. During this evolution scientists claim that their scales were transformed into wings and feathers.

3. Bats cannot and do not sit on trees like birds or other animals do. They cannot even stand on their feet, so they generally hang upside down high branches of trees.

4. There are about 3,700 different kinds of lizards .

5. Lizards also hibernate in the winter like bears and some other animals.

6. The rattle snake’s tail is made up of cup-shaped hard horny joints which fit loosely into each other.When the snake is disturbed,angry or excited, its tail begins to rattle.The sound is created as a result of the joints knocking on each other .

7 Tortoises and turtles catch insects to feed on by shooting out their sticky tongues. However, they do not feed only on insects.They feed on plants too.

8. The largest shark can grow up to 15 metres in length.

9. Alligators and crocodiles look very much alike but there are some differences. One of the main differences is that in the case of a crocodile its fourth tooth is always visible even when it closes its mouth.

10. A chameleon has transparent skin. Under this skin there are layers of cells which have yellow ,black and red pigments.When the chameleon is excited disturbed or even angry these colour cells contract and expand. So when this happens there is a change in the colours on its skin.

11. Yes.

12. The number of eggs a female frog lays may vary from two thousand to eight thousand eggs.

13. The Brazilian female frog lays its eggs in a nest of mud. They can be found in clusters, joined together by a sticky substance.

14. The snake swings its body side-ways into curves and loops to get speed and easy momentum.

15. A guineapig is not a pig but a kind of rodent which is kept as a pet .