Adult male and female gorillas differ in size and weight. Adult male gorillas are usually around 5 ft 5 in-5 ft 9 in (165-175 cm) tall. They often weigh about 140-200 kg (310-440 lb). Females are often half the size of a silverback male, and average about 140 cm (4 ft 7 in) tall and 100 kg (220 lb). Silverbacks of over 183 cm (6 feet) and 225 kg (500 lb) have been recorded out of captivity. Obese gorillas in captivity have been known to reach a weight of up to 270 kg (600 lb). All gorillas move around by knuckle-walking, meaning they walk on the knuckles of their hands. Gorillas have a facial structure described as prognathous. This means that, their mandible (lower jaw) sticks out farther than the maxilla (upper jaw). 
Gestation for gorillas is 8½ months long. There is normally 3 to 4 years between births. Infant gorillas live with their mothers for around 3-4 years. Females usually mature when they are 10–12 years of age, but mature earlier in captivity. Males mature between 11–13 years old. Average lifespan is within 30–50 years old. The longest recorded lifespan of a gorilla was 54 years, set by Massa at the Philadelphia Zoo.
Gorillas are omnivores, so they eat leaves, fruits, shoots, and occasionally insects, making up only 1 or 2% of their diet. Most gorillas have type B blood types. Gorillas also have individual fingerprints, like humans. 
Female gorillas are sexually mature by the time they are seven to eight years old, but they usually do not reproduce until they are ten years old. Males are rarely strong and dominant enough to reproduce before they reach 15 to 20 years of age. Gorillas can breed all year round. Female Gorillas are in estrus for one or two days each month and only the dominant silverback has breeding rights. Gorillas are polygynous in nature, which means the dominant silverback will mate with a number of females in his troop  or group of gorillas. 
(G. b. beringei)