Planet Earth Disc #2 Caves/Deserts/Ice World - Research Paper Example

One of the first topics discussed in the video was how caves are formed. Caves primarily form in rock formations where limestone is the most prominent type of rock. Limestone is created from creatures that live in the ocean. Over millions of years, the calcium structures that make up these tiny creatures build up on the oceans floor and are compressed to form limestone. When fresh water hits the limestone, small bits of the calcium are dissolved. This is because most fresh water is slightly acidic.

The running water carries away the calcium leaving a small void behind. This void is a cave. This same process also forms some of the structures found in caves such as stalactites and stalagmites. The formation of these structures all depends on how rapidly the water is flowing through the rock. If it is a slow drip, a stalactite will form on the cave ceiling. If the drip is more rapid, then a stalagmite will form on the floor of the cave. One extraordinary cave was not created by fresh water.

The cave was actually formed from an interaction between limestone and sulphuric acid. This interaction created structures made out of gypsum. This cave is a natural wonder and is protected by the government of Mexico. A second topic was how the animals that live in cave survive. The video explained now an ecosystem can be established with the absence of sunlight, which provides the energy necessary for most of the earth’s ecosystems. In a cave in Borneo, approximately three million bats nest each day.

At night, they fly out into the forest to get food. Their droppings have accumulated a one hundred meter high pie of guano. This guano supports an entire ecosystem of cockroaches and other creatures that form a complex and fragile food web. Other animals use the darkness to trick their prey. Glow worms have a tail that lights up to attract insects. The insects are drawn to the glow worm’s illumination and become trapped in a sticky web. The glow worm then devours the insect much in the same way a spider devours its prey.

Another topic of the video dealt with the physical formation of deserts. Deserts are very dry places by definition, but they are formed in different ways. Some, like the Atacama and the Gobi deserts are in the rain shadows of very large mountains. The Himalayas and the Andes block the flow of air from east to west or south to north. As the air is forced upwards to flow over these barriers, the moisture is forces out. Clouds form and the rain fall on the slopes of the mountains. By the time the air makes it over the mountains, all of the moisture is gone.

Another feature that helps these deserts to form is the presence of a cold water current along the coast. This causes air flowing over it to cool. Air that has been cooled is less likely to form clouds that lead to precipitation, so the land areas on the other sides of the current are dry. A final topic dealing with deserts centers on the methods wildlife use to survive in such a harsh climate. The heat is intense so animals use special skills to cope. Most animals find refuge underground during the day.

They burrow into the sand or hard soil of the desert floor. Others, like kangaroos, are too large for this. They seek shelter under trees and use saliva to keep their bodies from overheating. They lick their forearms and as the saliva evaporates, the blood under their arms is cooled. Other animals such as camels stay out in the blistering heat but have adapted ways to store enough water in their bodies to make this safe. In deserts such as the Sahara, camels can drink as much as one hundred litres of water at a time.

Other camels have adapted ways to eat snow in the arid yet cold Gobi desert. Other animals develop ways to eat the flowers of succulent plants as a way of surviving the heat and aridity of these desert regions.