Penguins

Marine Birds of the Southern Hemisphere

Nov 4, 2007 John Blatchford

Penguins evolved away from land predators and are all flightless.

Always favourites because of their comical movements on land and their lack of fear, Penguins are a well-studied group of animals who add much to our understanding of the effects of global warming. They are well adapted for fishing in their cold-water environment and nesting on snow and ice.

Penguin Distribution

Penguins are only found in the southern hemisphere - interactive distribution map of Penguin breeding sites - although a similar bird, the Great Auk, once lived in the Atlantic. 16 of the 17 species of Penguin live in cold places, but the Galapagos Penguin lives on the equator and fishes in the cold water of the Humboldt and Cromwell Currents.

Penguins and Flight

Penguins are thought to have evolved from birds that could fly, but they gradually lost this ability as they adapted fully to their marine environment. Their lack of land predators allowed them to survive in southern waters, but a similar evolutionary experiment in the north (the Great Auk) was cut short by hungry sailors – reminiscent of Steller’s Sea Cow. The only sea-going birds left in the northern hemisphere with the ability to ‘fly’ underwater have also retained the ability to fly in air – a good example would be the Puffins.

Penguins – Cold Feet

There is a classic question – Do Penguins get cold feet? – and the answer must surely be ‘YES’. If you walk on snow and ice your feet certainly get cold. What the question is really asking is ‘How do Penguins manage to keep warm enough to survive when their feet get so cold?’. The answer to that one is that they have a very cunning solution to the problem – they do not allow much heat to escape from their extremities. This is achieved by passing the blood that enters the legs through ‘Rete mirabile’ which are an anatomical trick that exchanges the heat between the blood leaving the feet and that which enters. Enough warm blood passes to stop the feet freezing, but not enough to cool the Penguin down too much.

Penguins – Fear of Humans

Penguins have no natural land predators, and since they have only ‘met’ humans who pose no threat they exhibit little fear. Visitors can approach them up to about 3 metres before the Penguins get worried, and Penguins sometimes walk right up to visitors to check them out - they are fascinated by cameras!. This phenomenon can be clearly seen by a visit to Edinburgh Zoo. Watch a video of the Penguin Parade at Edinburgh Zoo.

Refs: www.pinguins.info and National Geographic

Other articles by John Blatchford

The copyright of the article Penguins in Marine Biology & Oceanography is owned by John Blatchford. Permission to republish Penguins in print or online must be granted by the author in writing.