Beavers and otters are semi-aquatic mammals often confused due to similar habitats. However, they exhibit distinct physical characteristics, lifestyles, and dietary preferences. Understanding these differences reveals their unique adaptations.
Distinguishing Physical Features
Beavers are larger and more robust, typically weighing 35-65 pounds and measuring 3-4 feet, including their tail. Their broad, flat, paddle-like tail, covered in leathery scales, serves as a rudder for swimming, a prop on land, and a danger signal. Beavers possess prominent, continuously growing orange incisors, strengthened by iron, essential for gnawing wood. Their hind feet are fully webbed for powerful aquatic propulsion, while front paws are smaller and dexterous for manipulating objects.
Otters have a sleek, elongated, streamlined body. Their muscular, fur-covered tail tapers to a point, helping them steer and propel swiftly through water. They typically weigh 10-33 pounds and measure 2.5-5 feet. Otters have smaller, rounded ears and sensitive facial whiskers for locating prey underwater. All four paws are webbed, though less prominently than a beaver’s hind feet, and they have non-retractable claws.
Habitat and Lifestyle Variations
Beavers are known for their engineering, particularly dam and lodge construction. They build dams using branches, mud, and rocks to create deep-water ponds, providing predator protection and submerged lodge entrances. Lodges are typically built in these ponds or as burrows in riverbanks, with underwater entry points. Beavers prefer slow-moving water bodies like rivers, streams, and lakes, and are primarily nocturnal, conducting most building and foraging at night.
Otters lead a nomadic existence, often utilizing existing burrows along riverbanks or within root systems. They are highly agile in water, known for playful behavior, including sliding down banks. Otters prefer clean waterways, including rivers, lakes, and coastal areas. While active day or night, they spend considerable time on land. Their movement patterns involve fluid swimming and terrestrial excursions, contrasting with the beaver’s static, habitat-modifying approach.
Divergent Diets
Beavers are herbivores. They primarily consume tree bark from aspen, willow, birch, and maple trees. Their diet also includes leaves, twigs, roots, and aquatic vegetation like water lilies and cattails. Beavers continuously gnaw on wood for food and to maintain the length and sharpness of their ever-growing incisors. They often store branches underwater near their lodges as a winter food cache.
Otters are carnivores, predominantly eating aquatic organisms. Fish is their staple, but they also hunt crustaceans like crayfish and crabs, amphibians such as frogs, and sometimes small mammals or birds. Their keen senses, including sensitive whiskers, aid in detecting and capturing underwater prey. Otters are active hunters within aquatic ecosystems.