Grizzly Bear Anatomy: Hump, Claws, Skull and Body Parts

Grizzly bear anatomy is built for raw power. The grizzly (Ursus arctos horribilis) is a North American subspecies of brown bear distinguished by its massive shoulder hump, dished facial profile, and four to five inch claws designed for digging. Adult males weigh between 180 and 360 kg (400 to 790 lbs), and exceptional individuals have been recorded at over 680 kg (1,500 lbs). Every part of a grizzly’s body, from skull to claw, reflects a life of foraging, hunting, and surviving long winter hibernations.

This guide breaks down grizzly bear anatomy section by section, including the muscular shoulder hump, the structure of the skull and jaws, the paws and claws, the fur and coloration, the senses, and the internal adaptations that make months-long hibernation possible. It also covers how to tell a grizzly from a black bear, since the two species share much of the same range across North America.

Grizzly Bear Body Size and Build

Grizzly bears are among the largest land carnivores in North America. Adult males typically weigh 180 to 360 kg (400 to 790 lbs) and adult females weigh 130 to 180 kg (290 to 400 lbs), although coastal grizzlies in Alaska and British Columbia routinely exceed these numbers because their salmon-rich diet supports much heavier body weights. The largest verified wild specimen weighed approximately 680 kg (1,500 lbs).

Standing on all four legs, a grizzly stands roughly 1 to 1.4 meters (3.3 to 4.5 feet) at the shoulder. Reared up on its hind legs, a large male can reach 2.4 to 2.8 meters (8 to 9 feet) tall. The body is heavy-set and muscular, with thick limbs, a broad chest, and a comparatively short tail. Despite this bulk, a grizzly can run at speeds of up to 35 mph (56 km/h) over short distances, faster than the fastest human sprinter.

The Distinctive Shoulder Hump

The grizzly’s most recognizable anatomical feature is the muscular hump that sits between its shoulder blades. This hump is not a fat reserve. It is a dense mass of muscle anchored to a long extension of the spinal column, and it powers the bear’s forelimbs during digging. Grizzlies dig extensively, excavating winter dens up to 3 meters deep, unearthing roots and tubers, turning over rocks for insects, and digging out hibernating ground squirrels and marmots.

The hump also contributes to the grizzly’s powerful forward strike. A blow from a grizzly’s foreleg carries enough force to break the spine of an elk or moose. Black bears lack this hump entirely, which is the single most reliable visual feature for telling the two species apart in the field. When a grizzly is walking on level ground, the hump sits clearly higher than the rump, giving the bear its characteristic sloping back profile.

Grizzly Bear Skull, Jaws and Teeth

A grizzly’s skull is large, broad, and heavily built, with a concave or “dished” profile when viewed from the side. The forehead rises sharply above the snout rather than running in a straight line, a feature that separates grizzlies from black bears (whose skulls have a flatter, straighter facial profile). The skull anchors the powerful jaw muscles that close the bite.

Grizzlies have 42 teeth, including four prominent canines used for gripping prey, sharp incisors at the front, and large molars at the back. The molars are flatter and broader than those of more strictly carnivorous animals, reflecting the grizzly’s omnivorous diet of fish, mammals, insects, berries, roots, and grasses. Bite force is estimated at around 1,200 PSI, strong enough to crush bowling balls and large bones. Wildlife biologists measure grizzlies by skull length and width, and the largest skulls on record exceed 70 cm (27 inches) end to end.

Grizzly Bear Paws and Claws

A grizzly bear has four paws, each with five toes. Every toe carries a single non-retractable claw, giving the animal 20 claws in total. The claws on the front paws are the longest and most distinctive feature of grizzly anatomy after the shoulder hump. They typically measure 5 to 10 cm (2 to 4 inches) and curve only slightly, an ideal shape for digging through hard soil and tearing apart logs and termite mounds.

The paw pads are large, thick, and covered in tough skin that acts like a natural snowshoe, distributing the bear’s weight evenly across snow or soft ground. Front paws are noticeably larger than the hind paws and leave deeper, wider tracks. By contrast, black bears have shorter, sharper, more curved claws (about 2 to 5 cm) better suited for tree climbing. Adult grizzlies are too heavy and long-clawed to climb trees easily, although cubs can scramble up trunks to escape danger.

Fur and Coloration

Grizzly bear fur is dense, double-layered, and varies in color from pale blond and tan through cinnamon, mid-brown, and deep chocolate. The name “grizzly” comes from the silvery or white tips on many of the long guard hairs, which give the coat a frosted or “grizzled” appearance, especially across the back and shoulders. The legs and underside are often noticeably darker than the body.

The outer layer is made of long, coarse guard hairs that shed water and repel snow. The inner layer is short, soft underfur that traps a layer of warm air against the skin. Together these layers keep the bear comfortable in temperatures well below freezing. Grizzlies shed their winter coat during late spring and early summer, often appearing patchy and ragged for several weeks before the new coat grows in.

Senses: Smell, Sight, and Hearing

A grizzly bear’s sense of smell is its dominant sense and one of the most acute in the animal kingdom. The olfactory bulb of a grizzly’s brain is roughly five times the size of a human’s, and the bear’s nasal cavity contains hundreds of millions of scent receptors. A grizzly can detect a carcass from over 30 km (18 miles) away under the right wind conditions, and it can smell food buried under deep snow or sealed inside locked containers.

Hearing is also excellent and ranges into ultrasonic frequencies above the human threshold, useful for tracking small prey moving through grass and leaves. Eyesight is once thought to have been the weakest of the three senses, but recent research suggests grizzlies see in color and have visual acuity broadly comparable to humans, particularly for detecting motion. The eyes are positioned on the front of the skull, giving the bear binocular vision and good depth perception when judging distances during a charge or a precise paw strike.

Internal Anatomy and Hibernation Adaptations

The internal anatomy of a grizzly bear is shaped by the demands of hibernation. Before entering the winter den, a grizzly enters a state called hyperphagia in which it can consume up to 40 kg (90 lbs) of food per day and gain over 1 kg (2.2 lbs) of body weight daily. The liver enlarges, fat deposits build up around the body and inside the abdominal cavity, and the digestive tract gradually slows down.

During hibernation, which lasts five to seven months, the grizzly’s heart rate drops from around 40 beats per minute down to 8 to 12, body temperature falls only a few degrees, and metabolic rate falls to roughly 25 percent of normal. The bear does not eat, drink, urinate, or defecate during this period. Female grizzlies also display delayed implantation, in which a fertilized egg pauses development for several months and only implants in the uterine wall once the female has accumulated enough body fat to support pregnancy and lactation through the winter.

Grizzly Bear vs Black Bear: Anatomy Comparison

Grizzlies and black bears overlap across much of western North America, and people often confuse the two at a distance. Anatomy provides the most reliable identifying features, especially since coloration alone is unreliable: a black bear can be cinnamon or blond, and a grizzly can be very dark brown.

For more on the species, see the full Grizzly Bear profile and our guides to the Polar Bear and Spectacled Bear. For the closest anatomical comparison, see Polar Bear Anatomy. For other large predators, see Wolf Anatomy and Lion Anatomy, or browse the full Animal Anatomy hub.

Sources & References

• IUCN Red List, Ursus arctos
• U.S. Fish & Wildlife Service, Grizzly Bear species profile
• National Park Service, Grizzly Bear (Yellowstone)
• Animal Diversity Web, Ursus arctos
• Wikipedia, Grizzly Bear