The Saturday briefing

KNOWLEDGE IS POWER

- by CAROLINE FORD

NOTHING'S BLACK AND WHITE: Penguins rely on Southern Ocean food supplies and, below, “Lootenant” Sulu

Is there anything you're yearning to know? Send your questions, on any subject, to the contacts given below, and we will do our best to answer them...

I've often wondered why penguins, which tend to live in cooler climates, are not found in the northern Arctic regions. Why is that?

Sophia Lees, Northwich

Fossil evidence suggests that penguin ancestors evolved in the southern hemisphere about 60 million years ago.

There are 18 to 20 species of modern penguins, and all but one are found south of the equator - from Antarctica to the southern coasts of Africa, Australia, New Zealand and South America. The one exception is a lone species unique to the Galápagos Islands.

Contrary to popular belief, penguins are not specifically dependent on a cold climate but on nutrient-rich waters. While both poles have fish, specific foods that penguins rely on, such as krill, are less abundant in the Arctic compared to the Southern Ocean.

In the tropical Galápagos and Peru, the Humboldt Current - which carries deep, cold water from near Antarctica northward - fuels phytoplankton blooms that the abundant krill feed on.

It's likely penguins haven't spread further north due to flightlessness hindering their migration and because the warm, tropical waters between the poles acts as a barrier.

Even if they were able to migrate to the North Pole, the thick sea ice would be a problem for penguins, which need to be able to surface in open water to hunt.

Being ground-nesting and unable to fly, penguins and their eggs would be also vulnerable to the Arctic's predators, such as foxes, wolves and polar bears.

In 1936, explorer Lars Christensen brought nine king penguins to the Lofoten archipelago and Finnmark in Norway. With no predators, he hoped to establish a colony.