Giraffe: An 11 kg Heart and 2.4 m Neck

The giraffe is the tallest land animal alive. A full-grown bull can stand more than five metres tall from hoof to ossicone tip, browses on leaves that no other savanna herbivore can reach, and carries a neck so long it has rewritten textbook assumptions about mammalian anatomy.

Despite a silhouette that looks almost cartoonish against an African skyline, the giraffe is a formidable, fast and biologically extreme mammal whose body represents one of the most specialised solutions to high-canopy browsing on Earth.

This guide covers every major aspect of giraffe biology and ecology: size and build, neck and cardiovascular adaptations, diet, reproduction, social behaviour, range, conservation status and the relationships between giraffes and the people sharing their habitat.

Etymology and Classification

The scientific name Giraffa camelopardalis was assigned by Carl Linnaeus in 1758 and literally means "camel-leopard." Early Greek and Roman naturalists believed the giraffe was a hybrid of those two animals, it had the overall body plan of a camel and the spotted coat of a leopard. The common English name "giraffe" descends from the Arabic zirafah , a word of unclear origin.

Giraffes sit within the order Artiodactyla (even-toed ungulates) alongside cattle, deer, antelope, camels, hippos and whales, and in the family Giraffidae, which today contains only one other living genus: the okapi ( Okapia johnstoni ), a shorter-necked forest cousin from central Africa. Giraffidae once included more than ten fossil genera, only two genera survive today.

Taxonomic debate is active. The traditional view treats Giraffa camelopardalis as a single species with nine subspecies: Nubian, reticulated, Rothschild's, Masai, Thornicroft's, South African, Angolan, Kordofan and West African.

Genetic work published from 2016 onwards proposes four distinct species, northern, southern, reticulated and Masai giraffes, with several of the traditional subspecies collapsing into one of those four. The four-species model is supported by substantial divergence in mitochondrial and nuclear DNA.

Conservation status may change depending on which taxonomy prevails, since the IUCN currently assesses giraffes as a single species complex.

Size and Physical Description

Giraffes are the tallest terrestrial animals on Earth. Sexual dimorphism is pronounced but not as extreme as in polar bears or elephant seals.

Males (bulls):

• Total height: roughly 4.5-5.7 m
• Neck length: up to 2.4 m
• Weight: average about 1,192 kg

Females (cows):

• Total height: 3.5-4.5 m
• Weight: average about 828 kg

Calves at birth:

• Height: 1.7-2 m

Giraffes structure their bodies around neck design. Limbs are proportionally very long, forelegs being slightly longer than hind legs creates the sloping back visible even from a distance. Chests are deep but narrow, enabling the animal to pivot its neck and shoulders among widely spaced tree trunks.

Hooves are large, reaching about 31 cm by 23 cm on large males, and deliver a powerful kick. The tail is long and ends in a dark tuft of hair used to flick biting flies from the flanks and hindquarters.

The coat pattern, irregular dark patches separated by lighter lines, is one of the most recognisable in the animal kingdom. Patterns vary between subspecies: reticulated giraffes have sharp polygonal patches separated by thin white lines, while Masai giraffes carry jagged, star-shaped patches with fuzzy borders.

Within any population the pattern is unique to each animal like a fingerprint, and researchers now use photographic pattern-matching software to identify individuals across years of field data. The patches are not merely cosmetic.

Beneath each patch sits a dense network of blood vessels that helps dump heat, and the patterns likely provide camouflage in dappled acacia shade from the perspective of lions hunting at ground level.

The Neck: Seven Bones and a Pressure Pump

Contrary to common assumption, giraffes have the same number of cervical vertebrae as humans, seven. What is extreme is the length of each vertebra. In an adult giraffe each cervical vertebra is over 28 centimetres long, and the neck can reach 2.4 m in length.

The neck serves two primary functions. The first is feeding: a giraffe can feed up to about 4.5 metres above the ground, while even a large competitor such as the kudu can feed only up to about 2 metres. The second function is combat.

Male giraffes fight by standing shoulder to shoulder and swinging their necks sideways in a behaviour called necking . The ossicones at the top of the skull act as the striking head of a long club.

Holding a two-metre column of blood against gravity requires extraordinary cardiovascular engineering. The giraffe heart weighs up to 11 kg and must generate roughly double the blood pressure a human needs to supply the brain, and the heart wall can be as thick as 7.5 cm.

The same high pressure that pushes blood up the neck would slam into the brain when the giraffe lowers its head to drink. Three adaptations prevent this.

• One-way jugular valves. The major veins of the neck contain valves that prevent gravitational backflow toward the brain.
• Rete mirabile. A network of blood vessels in the upper neck, with a large cross-sectional area, prevents excess blood flow to the brain when the head drops.
• Tight lower-leg skin. The skin of the lower legs is thick and tight, preventing too much blood from pouring into the legs.

Together these adaptations let a giraffe bend to drink from a waterhole and then rear back up into full height without fainting, blacking out, or rupturing cranial vessels.

The Tongue, Mouth, and Diet

Giraffes are browsing herbivores, specialised for stripping leaves and shoots from thorny trees. Acacia species dominate the diet across most of the range, with combretum, myrrh and various other woody species providing seasonal variety. In the wet season food is abundant and giraffes spread out, in the dry season they gather around the remaining evergreen trees and bushes.

The tongue is one of the most striking feeding tools in mammalian biology.

• Length: up to 45 cm
• Colour: black
• Structure: prehensile, muscular, highly mobile

The dark pigment may protect the tongue against sunburn. The prehensile tip wraps around acacia branchlets, drawing them into the mouth past the thorns. The flexible, hairy upper lip protects against sharp prickles, and the upper jaw has a hard palate instead of front teeth.

A giraffe eats around 34 kg of plant matter daily. Feeding peaks in the first and last hours of daylight, and giraffes mostly stand and ruminate in between. Giraffes are ruminants with a four-chambered stomach, and rumination is the dominant activity at night, mostly done lying down.

When it has access to water, a giraffe will go no more than three days without drinking. To reach down to drink, it either spreads its front legs or bends its knees.

Ossicones: Not Horns

The growths on a giraffe's head are not horns. They are ossicones , a distinct anatomical structure found in the Giraffidae family. Ossicones form from ossified cartilage, are covered in skin and fur and fuse to the skull only after birth. Both males and females have them.

• Males develop thicker, often balder ossicones, worn smooth by years of necking combat.
• Females retain the fur tuft at the tip and generally have thinner ossicones.
• A lump, more prominent in males, emerges in the middle of the skull and older bulls develop calcium deposits that form additional bumps on the skull.

Because ossicones are fused ossified cartilage rather than keratin sheaths over bone, they grow differently from the horns of antelope or cattle. They are also far more useful as clubs. As males age, their skulls become heavier and more club-like, which helps them in combat.

Locomotion and Speed

Giraffes walk with a pacing gait: both legs on the same side move together. This is unusual among large mammals, most use a diagonal gait in which opposing legs swing together. The pacing gait suits the giraffe's long legs and broad body, preventing the legs from clipping each other as they swing. It produces the characteristic swaying motion visible in any herd on the move.

At a gallop the gait changes dramatically. The hind legs move around the front legs before the front legs move forward. A giraffe can sprint at up to 60 km/h and can sustain about 50 km/h for several kilometres.

The giraffe's vertical reach and open-country speed, combined with a ground-shaking kick, make predation risk relatively low for healthy adults. Lions, leopards, spotted hyenas and African wild dogs may prey on giraffes.

Life Cycle and Reproduction

Giraffe reproduction runs on a long, slow calendar reflecting the species' size and low-predation adult ecology. Reproduction is broadly polygamous: a few older males mate with the fertile females.

Oestrus is detected by males through flehmen response: a bull tastes a cow's urine to detect whether she is in oestrus. Dominant bulls roam widely in search of receptive females and fight off rivals with necking displays and contact combat.

Reproductive calendar:

Stage	Duration
Gestation	400-460 days

Females give birth standing up. The calf emerges head and front legs first and falls to the ground, severing the umbilical cord. Within a few hours of birth the calf can run around.

Mothers with calves gather in nursery herds, and a mother will stand over her calf and kick at an approaching predator. Calves are at risk of predation. Mothers in such a group may sometimes leave their calves with one female while they forage and drink elsewhere.

Twins occur only on rare occasions.

Social Behaviour

Giraffe social structure was long considered loose or essentially absent, individuals appeared to wander between loose groups with no stable associations. Long-term tracking studies have since revised that picture substantially. Giraffes form fission-fusion societies with measurable preferences for certain associates. Groups of females may be maternally related.

Males follow a different pattern. Young bulls form loose bachelor groups in which they spar and practise necking without serious injury. As they mature they leave those groups and roam alone or among cows searching for mating opportunities. Dominant bulls do not hold territories in the classical sense, they hold a social rank that travels with them and is tested at every new encounter.

Communication includes visual displays, ossicone posture, scent cues and vocalisations. For most of the twentieth century giraffes were described as essentially silent. Modern recording technology has changed that picture. Giraffes appear to hum to each other during the night. Whether the humming is communicative, involuntary, or a form of contact call is still under investigation.

Sleep and Rest

Studies in captivity found that giraffes sleep intermittently for around 4.6 hours per day, mostly at night. They usually sleep lying down, although standing sleep has been recorded, particularly in older individuals.

Intermittent short deep-sleep phases while lying are characterised by the giraffe bending its neck backwards and resting its head on the hip or thigh, a position believed to indicate paradoxical (REM) sleep.

Range, Habitat, and Subpopulations

Giraffes are endemic to sub-Saharan Africa. Historical range covered a wide arc from the Sahel across the savannas and open woodlands of East, Central and Southern Africa. Today the range is heavily fragmented, with many formerly contiguous populations now reduced to isolated pockets separated by farmland, infrastructure, or conflict zones.

Present-day distribution by region:

Region	Subspecies or species (lumped / split)	Notes
East Africa	Masai, Reticulated, Rothschild's / Nubian	Largest populations; core of reticulated giraffe range
Southern Africa	South African, Angolan / southern giraffe	About 13,000 Angolan and up to 31,500 South African giraffes (older estimates)
West Africa	West African / northern giraffe	Endemic to southwestern Niger; about 400 individuals
Central Africa	Kordofan / northern giraffe	Includes southern Chad, the Central African Republic and northeastern DRC; about 2,000 individuals

Giraffes favour scattered acacia-dominated savanna and open woodland, avoiding both dense closed-canopy forest (too dark and too tangled for their body plan) and true desert (too little forage). They can, however, tolerate very dry conditions: the Angolan giraffe can be found in desert environments.

Conservation Status and Threats

The IUCN lists Giraffa camelopardalis as Vulnerable , as a species complex. Estimates as of 2016 indicate approximately 97,500 giraffes in the wild. Some subspecies or proposed species are in substantially worse condition: Kordofan and Nubian giraffes number only about 2,000 individuals each.

Primary threats:

• Habitat loss and fragmentation. Savannas across Africa are converted to farmland, grazing and infrastructure at rapid rates. Fragmentation isolates populations and disrupts the long-distance movements on which giraffes depend for seasonal forage and genetic exchange.
• Illegal hunting. Giraffes are poached for meat, tail hair (used in traditional jewellery and talismans), hides and bone marrow, which is associated in some regional beliefs with health benefits.
• Civil unrest. Populations in Central and West Africa have been devastated by decades of conflict in range states, which disrupts park management, increases unregulated hunting and displaces human communities into formerly remote wildlife areas.
• Drought and climate stress. Prolonged drought reduces available forage, concentrates animals around shrinking water sources, and compounds nutritional stress during calving years.
• Road and power-line collisions. Tall animals crossing modern infrastructure are surprisingly vulnerable to vehicle strikes and, in certain corridors, to electrocution on low-slung power lines.

Conservationists describe the giraffe decline as a silent extinction because the species has attracted far less attention than elephants, rhinos, or great apes despite losing a larger proportion of its population.

Community-based conservancies in East Africa, population restoration through translocations, intensive anti-poaching patrols and photographic monitoring networks that follow individual giraffes across their lives form the core conservation strategy.

Giraffes and Humans

Giraffes have been part of the African cultural landscape for as long as humans have shared it. San rock art in southern Africa depicts giraffes with striking accuracy, ancient Egyptian reliefs show them among tribute animals delivered from the south, medieval Chinese envoys returned from East Africa with a giraffe that was presented at the Ming court as a symbol of cosmic harmony. The animal's distinctive silhouette has made it an enduring emblem of the African savanna.

Modern relationships are more complicated. Giraffe tourism generates meaningful income for communities bordering East African reserves, with photographic safaris anchoring economies in parts of Kenya, Tanzania and South Africa. Conservancy models, in which local communities share revenue from wildlife tourism, are one route to supporting giraffe conservation.

At the same time, trophy hunting remains legal in parts of southern Africa, and the international trade in giraffe products (bone carvings, hides, bone marrow) sparked a successful push to list the species under CITES Appendix II in 2019, tightening regulation of cross-border trade.

Giraffes are rarely dangerous to humans, but they are not harmless. A startled giraffe defending a calf can seriously injure a person with a kick, and captive handlers occasionally sustain serious injuries. Wild giraffes are generally wary of humans on foot and tolerant of vehicles, making them one of the more approachable large mammals in well-managed reserves.