Giraffe

Description

The giraffe (Giraffa camelopardalis) is an African even-toed ungulate mammal, the tallest of all land-living animal species. Males can be 4.8 to 5.5 metres (16 to 18 feet) tall and weigh up to 1,300 kilograms (3,000 pounds). The record-sized bull was 5.87 m (19.2 ft) tall and weighed approximately 2,000 kg (4,400 lb). Females are generally slightly shorter, and weigh less than the males do.

The giraffe is related to deer and cattle, but is placed in a separate family, the Giraffidae, consisting only of the giraffe and its closest relative, the okapi. Its range extends from Chad to South Africa.

Giraffes can inhabit savannas, grasslands, or open woodlands. They prefer areas enriched with acacia growth. They drink large quantities of water and, as a result, they can spend long periods of time in dry, arid areas. When searching for more food they will venture into areas with denser foliage.

Anatomy

Male giraffes are around 4.5-5.5 m (16-19 ft) tall at the horn tips, and weigh 770-1900 kg (1700-4200 lb) Females are 30-60 cm (1-2 ft) shorter and weigh about 200 kg (400 lb) less than males. Giraffes have spots covering their entire bodies, except their underbellies, with each giraffe having a unique pattern of spots.

Circulatory system

Modifications to the giraffe's structure have evolved, particularly to the circulatory system. A giraffe's heart, which can weigh up to 10 kg (22 lb) and measure about 60 cm (2 ft) long, has to generate around double the normal blood pressure for an average large mammal in order to maintain blood flow to the brain against gravity. In the upper neck, a complex pressure-regulation system called the rete mirabile prevents excess blood flow to the brain when the giraffe lowers its head to drink. Conversely, the blood vessels in the lower legs are under great pressure (because of the weight of fluid pressing down on them). In other animals such pressure would force the blood out through the capillary walls; giraffes, however, have a very tight sheath of thick skin over their lower limbs which maintains high extravascular pressure in exactly the same way as a pilot's g-suit.

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