My Science School

Most of the sea animals that can be dangerous to us are too timid to attack humans. These include the dangerous-looking reef shark and the sea snake. Although a number of fishermen die from the poisonous bite of the sea snake, the animal itself is usually too lazy to bite. Another dangerous inhabitant of the sea is the puffer fish. Some of its body parts are highly poisonous, especially the liver and ovaries. Despite this, its meat is served as a delicacy and a few people have also died because of eating incorrectly cooked puffer fish. The sea wasp is one of the most poisonous animals of the world. The stinging cells of this species of jellyfish contain a poison which can cause death within minutes. Annually, up to 70 people die because of sea wasp stings. 

 

 Mangroves are plants that grow in the tidal zone of tropical coastal areas and are constantly subjected to ascending and descending water levels of high and low tides. They have adapted to this environment by anchoring themselves in the soil with their stilted roots. This way, they also prevent the coast from being destroyed by storms or flood waves. After the devastating tsunami of 2004, many countries have started planting mangroves at the coasts to try and prevent similar catastrophes in future.

The sea turtles developed from land turtles about 200 million years ago. Their legs transformed into broad fins and the armour gradually acquired a streamlined shape to generate less resistance while diving. Due to its flat armour, the animals cannot retract the head when it senses danger. Sea turtles spend their whole life in the sea and go on land only for laying eggs. The female turtles dig a hole in the sand with their flippers, lay the eggs in the whole (nest), re-fill the nest with sand and then return to the ocean. Hatching usually takes place at night, when there is a lesser chance of predators like seagulls being around. Once the young ones reach the surface, they instinctively head towards the sea. 

Coral reefs consist of skeletons of small animals, called madrepores, and stacked one on top of the other for centuries. These corals obtain minerals from the seawater and build a hard structure of limestone. These hard portions of dead corals form the actual coral reefs, the corals that are alive are found on the surface of the reef. 

Continue reading "How is a coral reef formed? "

The tropical seas with their colourful coral reefs are one of the most conspicuous habitats of the world. The bizarre-shaped coral reefs provide home to many colourful fish, snails, sea urchins, prawns, and shells. Other inhabitants are also present in the water—sea turtles, whose armour is flatter than that of the land turtles, hammerhead sharks with their hammer-shaped broad head, and some other animals that are even more dangerous than sharks. 

Fish move by flapping their fins or through wriggling movements of their body. In addition, they have an air bladder, which they can fill with gases when needed. These features make them lighter and they can float in the water like a submarine. Jellyfish usually drift. To move forward, they pull together their cap and push the water downwards—a same recoil principle that is used in jet fighters and octopuses. 

Pelicans use the sack for catching fish. Interestingly, different species of pelicans use different hunting methods. Some hunt in a semicircular formation and drive the fish from deep to shallow water so that the fish cannot dive down. The pelicans then immerse their long beaks in the water and scoop the fish in their sacks. The baby pelicans feed by taking the fish from the sack of the parents. Another species, the brown pelicans, does a vertical nosedive in the water from a height of 10-20 m and fills its sack with fishes from the deep water.

 

The growth rate of the frog’s population is the same in ponds near the coast or in the garden at home. Tadpoles develop from fertilized gelatinous eggs. These are larvae of frogs, which have gills and move forward with the help of a tail. Gradually, they go through a transformation to become a frog. The process is called metamorphosis. The tadpoles develop front and back legs, cartilages become bones, the tail retracts, lungs develop, and the gills regress. Now, it can move on land as well as water. Such a metamorphosis takes place in other animals too, for instance in butterflies or beetles.

 

Salt meadows are area at the sea coast that are not flooded daily by sea water like the tidelands or the beaches. They are flooded only by the high tide at regular intervals. The soil in these areas contains salt and is poorly ventilated; therefore, only a few plants can survive. Plants having an affinity for salt, like the beach lilac and the beach aster, grow here. Since the meadows sink completely in the strong sea at high tides, the plants of the salt meadows have resistant stalks and leaves to withstand the forces of the wine and the sea.

Frogs croak in freshwater ponds, and a few metres ahead, fish and jellyfish swim in the salt water of the sea. The narrow coastal land between the land and the sea could contain steeply falling coastal cliffs or flat coastal regions, which are flooded regularly like the sensitive tideland and salt meadows.  Continue reading "Who lives along the coasts?"

The highest mountain peak of the world is Mount Everest with a height of 8850 m. Animal do not live on ice-covered mountain peaks and in the areas where even mountaineers can manage only with an oxygen flask. Animals that have adapted themselves to the rough conditions live below a height of 6000 m - goat-like animals such as Himalayan tahrs, ibexes and cashmere goats, the pikas with their small ears and the endangered snow leopard. Yaks are also found here, which the local people use for carrying loads. 

There are two wild species of camels in the highlands of the South American Andes: vicunas and guanacos. Contrary to their Asian and African counterparts, the two-humped Bactrian camel and the single-humped Arabian camel respectively, vicunas and guanacos do not have any humps and are also much smaller. Guanacos live in open grasslands at a height of up to 4000 m, and vicunas live in higher regions. About 5000 years ago, humans started breeding animals in the Andes, which gave rise to the species of lama and alpaca. The smaller alpacas provide very soft wool.

The term ‘tree-line’ describes the height above which trees can no longer grow in the mountains. The main reason for this is the very low temperature in these places. If we climb a mountain, we find a temperature drop of about 6°C for every kilometre. In addition, the temperature fluctuations between day and night as well as summer and winter are very high. The soil cover is thin so the roots of trees do not get a firm hold. Only small pine trees, cedars, grass, and moss grow above the tree-line before the start of the rocky and icy area. 

Groundhogs live in widely branched burrows below the ground, but come out on the surface every day to collect grasses, seeds, and insects. A few species live in colonies in high mountains. They divide work amongst them—when a few animals have gone out in search of food, the others are on guard. If they sense danger from approaching enemies, they emit a shrill whistle to warn the others. In the summer, the animals must feed enough to put on a thick layer of fat so that they can survive the 6-9 months long winter sleep. 

Both animals have adapted to their mountain habitat. The chamois live in the upper mountain forests and fields and climb higher only in summers. The ibexes, on the other hand, live in icy and rocky regions and look for food in mountain meadows. They never go down to the forest. Species of ibexes are found in the mountain regions of Europe and Asia, on the Arabian Peninsula, and in north-eastern Africa. Chamois, on the other hand, are found only in the mountains of Europe: in the Alps, Carpathian Mountains, and Pyrenees as well as in Caucasus Mountains.