The Earth Story

Original caption:

Reindeer

As Christmas approaches, I’m reminded of the days when my sons were small and we (rightly or wrongly) encouraged their belief in that “jolly old elf” and flying reindeer. The requisite cookies and milk were left out, along with carrots and celery sticks for the reindeer (as I recall, somebody else consumed the cookies and I got stuck with the vegetation…). When little boys needed to go to bed so that Christmas magic could occur, the sound of sleigh bells could be heard outside the house, causing them to dive under the covers and squeeze their eyes tightly shut.

Although reindeer did not become associated with the holiday of Christmas until 1822, when mentioned in Clement Clarke Moore’s poem, “An Account of a Visit from St. Nicholas,” Rangifer tarandus have definite connections to snow and ice. Found in the biome known as the taiga (the Russian word for snow), reindeer have been a central part of the cultures of nomadic herders in parts of Scandinavia and Mongolia for thousands of years, where the animals were depended upon for meat, milk, and transportation. In many places, these cultures are disappearing as younger generations move away from traditional roles and lands.

Born in early spring, when much of the taiga is still covered in snow, reindeer calves are protected from the extreme temperature changes at birth (as much as a 50-60°C drop in temperature) by large deposits of brown fat. Unique to mammals, brown fat is an adaptation for generating heat. Filled with mitochondria, the energy-producing organelles of the cell, the brown fat contains a network of capillaries that carry the generated heat throughout the body. Mostly active over the first month of life, the brown fat gradually changes and becomes more like white fat.

Well-adapted for living in arctic climates, reindeer also possess a smaller surface area-to-body-mass ratio to reduce heat loss, as well as a winter coat made up of thick, hollow guard hairs over a woolen-like underfur. Because of these and other adaptations, these cousins of the caribou are able to tolerate temperatures below -30°C (-22°F).

Reindeer are cousins to the caribou found in other artic areas, such as Alaska, both being subspecies of Rangifer tarandus. Both are also migratory ungulates (hooved mammals), although reindeer tend to be more confined to specific home ranges than are caribou. Reindeer also tend to be stockier than caribou, with a flatter face and shorter legs. Both males and females of the species grow antlers (a trait not found in any other species of deer), which appear while they are still calves. Bulls and non-gestating females will typically drop their antlers in the winter, but pregnant females retain theirs until spring. This adaptation allows her to protect her food sources (mainly reindeer moss, a form of lichen) throughout the winter and thus ensuring sufficient nutrition for the developing fetus. She will drop her antlers within days of giving birth. CW

Image

http://bit.ly/1OBbn7I

Sources

http://reindeer.salrm.uaf.edu/about_reindeer/

http://www.reindeerherding.org/herders/sami-norway/

http://bit.ly/1QPwK9M

http://www.mnh.si.edu/arctic/html/caribou_reindeer.html

http://www.blueplanetbiomes.org/taiga.htm

http://www.uaf.edu/files/snre/MP_04_07.pdf

http://reindeer.ws/info.htm

Wonder lake One of the wonders of Denali National Park in Alaska it this beautiful body of water, seen here with mount Denali (6,168m) in the background. The landscape here is a combination of permafrost and tundra, deciduous Taiga forests and tall glaciated granitic mountains. The range of peaks is rising due to the subduction collision between the Pacific and North American plates that is responsible for the huge spine of the Americas, running south all the way from Alaska to Tierra Del Fuego in faraway Argentina and Chile. The park contains fragments of several of the micro terranes that have accreted on north America's west coast over the last hundred million years or so. Many have been metamorphosed, melted into granites and extensively folded and faulted by the immenso tremendous forces of continental collision. In fact this process provides a slow motion rough and ready answer to the old quandary of what happens when an irresitable force meets an immovable object.  Most of the terranes were oceanic sediments that were too buoyant to subduct, and their rocks were originally deposited in a variety of eras. The oldest is the Yukon-Tanana (1 billoin-400 million years old), now extensively transformed by its geological journey into medium grade metamorphic rocks. Next in line is the Farewell, a fossil rich sedimentary slice from the early half of complex life's evolution, dating from the Cambrian to the end Permian. The youngest terranes date from the Mesozoic era and consist of mixed sedimentary and igneous rocks, including pillow basalts first erupted under a sea full of ammonites and swimming reptiles. there is also an ophiolite sequence, where a chunk of oceanic crust has been pushed onto the continent , giving us a lovely insight into the marine crust/ shallow mantle interface. The youngest rocks comrpise something known as a flysh sequence, built up in the marine basin below the mountains where the plate was flexing down under the force of the grating subducting plates around a hundred million years back. The mountains are still growing and the many earthquakes in the area testify to the powerful forces stirring below. The recent ice ages sculpted all these rocks into the landscape we see today. Wonder lake itself is a glacial landform called a kettle, formed during the rapid retreat of the sheets when large chunks of ice melt more slowly than the rest because they are shielded by a protective layer of till (glacier shlep, rock dirt and flour). The overlying debris then settled and slumped forming the depression that has since been filled by rainwater and snow melt, though some of it was also directly carved out by glaciers. It is 6.5km long and up to 85 metres deep.  Loz Image credit: Rodney Lough Jr/ Nature's Best Photography http://www.nps.gov/dena/planyourvisit/campground-wonder.htm