The 400-pound mark (approximately 180 kilograms) represents a mid-range weight class in the animal kingdom, often separating medium-sized mammals from truly gigantic species. This weight is a point of reference that highlights biological diversity across different continents and environments. Animals near this weight often display sexual dimorphism, meaning 400 pounds may be the average for a larger male or a robust female. The variety of species—from marine predators to terrestrial omnivores—demonstrates an optimal size for many ecological niches.
Land Mammals of North America and Eurasia
The temperate and northern forests of North America and Eurasia host several terrestrial mammals where 400 pounds is a common adult weight, particularly for males. The American Black Bear, for example, has adult male weights that span a broad range. Males in regions with abundant food, such as the East Coast or areas with salmon runs, often average around 400 pounds, though some individuals can exceed 500 pounds.
Regional food availability strongly determines this size, with bears near urban areas being heavier than those in resource-scarce wildlands. In Eurasia, the Wild Boar (Eurasian pig) can also reach this mass, especially the largest subspecies. While many European males average closer to 220 pounds, the largest males in Western and Central Europe can weigh up to 440 pounds. This weight represents the upper limit for the most robust male wild boars in productive environments.
Apex Predators and Herbivores of Africa and Australia
In Africa and Australia, 400 pounds serves as a weight milestone for different types of animals. In the African savanna, this weight is often the maximum for a large predator or the mid-range for a substantial herbivore. A male Leopard, an apex predator across Africa and Asia, typically weighs 80 to 165 pounds. However, the largest individuals, particularly in mountainous regions, can sometimes reach or slightly exceed 200 pounds.
This weight class is more consistently occupied by medium-sized African ungulates, such as the Hartebeest, a large antelope. Most Hartebeest subspecies have an adult weight range extending up to 440 pounds, with the average adult weight being approximately 400 pounds. While the massive Common Eland, the world’s largest antelope, far exceeds this weight, a young calf or a smaller adult female may fall into the 400-pound range. In Australia, the Red Kangaroo, the largest living marsupial, has males that typically weigh up to 200 pounds, but the largest recorded individuals have reached around 400 pounds.
Aquatic and Semi-Aquatic Species
Aquatic environments introduce animals whose body mass is supported by water, allowing for different biological scaling. The Gray Seal, a marine mammal of the North Atlantic, is an example where the largest individuals exceed this threshold. Adult male Gray Seals (bulls) can reach weights of up to 880 pounds, although females are smaller.
The average weight for an adult female Gray Seal in the western Atlantic population often hovers around 495 pounds, placing them near this weight class. Among reptiles, the Loggerhead sea turtle, the world’s largest hard-shelled turtle, also approaches this weight. While the average adult Loggerhead weighs approximately 300 pounds, the largest specimens have been recorded weighing up to 440 pounds. For both marine mammals and large reptiles, 400 pounds represents a common upper limit or a weight achieved by the largest mature individuals.