BBC Planet Earth – Deserts
I chose the Planet Earth desert episode because I have lived in deserts for most of my life. I was born and raised in the Mojave desert (Las Vegas, NV) and I now live in the high desert of Kanab, UT (5000 feet). One third of the land on Earth is desert. Most deserts are located near the 30 degree latitude and are globally affected by the subtropical highs. Zones of high pressure build up at these latitudes mainly due to the Coriolis deflection which limits the poleward movement of air. This creates a buildup of air that results in clear, dry weather. The Planet Earth video explains that the desert is our Earth’s driest biome, but not all deserts are hot. Deserts can have very extreme temperatures. Few animals can survive these extremes. The desert animals have had to adapt to the high heat and lack of food and water. Bactrian camels are one of the few animals that has adapted to the lack of water. These camels live in the Gobi desert where the winter water is locked up as ice. The documentary shows how the camels eat ice in order to get enough water to survive. They eat small amounts many times a day. The winter is their breeding time due to the fact that they can travel far in the winter, eating ice along the way. The Gobi is a desert because of the rain shadow effect of the Himalayan mountains.
The African Saharan desert is the largest desert in the world and is as big as the United States. Sand storms can last for days and can be the size of Britain. Sand shapes all deserts. Reptiles are adapted to the desert sands by their scaly skin. Australia is the driest continent on Earth, every morning hour the temperature rises by 5 degrees centigrade. The red kangaroo must take shelter by mid-day. I really liked how the kangaroo uses an effective strategy of licking itself to keep itself cool. They also spend their time in the shade and dig to the cooler soil underneath. These strategies help them to make it through the hottest part of the day. The Fenic foxes of Africa have adapted to the heat by being nocturnal. They have very large ears that transfer their body heat very effectively. Most small desert creatures are nocturnal.
The Antacoma desert in Chile is the driest desert in the world. Some parts don’t get rain for 50 years! There is a South American camel that gets all the water that it needs from the cactus that it eats. The cactus survives, not by rainfall, but by dew. Special weather patterns; a cold sea current that runs parallel to the land cools the moist warm air above it and produces banks of fog. Wind drives the fog inland. The fog is so regular that even lichens survive in this desert. Without the fog this land would be empty. The Sonoran desert of Arizona is not as dry, but this desert gets much of its water through summer monsoons. The giant Saguaro cactus has adapted by taking up the water. It can store up to 5 tons of water after a heavy monsoonal rain. The trunks of these plants then provide homes and food for many animals. The success of the cactus brings life to the desert.
Utah deserts have a small cameo! Lots of great footage from around Moab and then a quick switch to Ibex fighting. These duels can last for over an hour. The fighting is exhausting in the heat. What usually kills animals in the desert is not the heat or the lack of water, but the lack of food. Many animals like the African elephant, have to travel for many miles a day in search of food. They in turn may be shadowed by lions. In the Savanah country , the lions prides are smaller and their territory ranges are much larger. The lions are always on the move to find enough food to live on. Periodic distant rains can bring water to the desert as a flash flood. Here in southern Utah we typically get several flash floods a year. These events are the most devastating natural disaster that we experience here in Kanab. Many people have homes flooded and landscaping ruined.
Death Valley is the hottest place on Earth. The locust and grasshoppers will swarm after water has come to the desert. These insects will consume everything that comes within its path. It is truly amazing to see how every animal, plant and insect has adapted to the harsh environment of the desert. Each organism has a unique niche that allows for its survival and exploitation of the water that is available. I really enjoyed the Planet Earth deserts segment; how plants and animals have adapted to this harsh environment and how understanding weather patterns helps us to protect these fragile environments.
