Largest fox

The world's largest species of fox is the red fox Vulpes vulpes, native to the entire northern hemisphere, including Eurasia, North Africa and North America (although some mammalogists have split off the North American red fox as a separate species, V. fulva). On average, adults measure 45–90 cm in body length, plus a 30–55 cm tail length, and a shoulder height of 35–50 cm, plus a weight ranging from 2.2 to 14 kg, with vixens normally weighing 15–20% less than males. American red foxes are lighter than Old World ones.

In stark contrast, the world's smallest fox, the fennec V. zerda, native to the Sahara Desert in North Africa, especially Algeria and Tunisia, has a body length of no more than 40 cm, and a thick bushy tail of around 20 cm. It also has disproportionately large ears, each of which measure up to 15 cm in length. Their function is to dissipate heat, which they are able to accomplish effectively owing to the abundance of small blood vessels near to the skin. They are also extremely sensitive aurally – so much so that the fennec can actually hear prey moving underground.