Science · Life Science

Hippopotamus

Reading comprehension passage and printable worksheet about the hippopotamus — its physical traits, semi-aquatic lifestyle, and place in African ecosystems — for grades 3–6.

Reading Passage

Hippopotamus

The hippopotamus — whose name comes from the Greek words for ‘river horse’ — is one of the largest land animals on Earth. An adult hippo can weigh up to 4,000 kilograms (about 8,800 pounds) and measure over 5 meters (16 feet) in length. Despite their enormous size, hippos are closely related to whales and dolphins — their closest living aquatic relatives. They are found in rivers, lakes, and wetlands in sub-Saharan Africa.

Hippos spend most of their time in water to keep cool and to protect their thick, sensitive skin from the intense African sun. They cannot sweat, but they do secrete a natural reddish-pink oily substance that acts as a sunscreen and skin moisturizer. This secretion also has antibiotic properties that help protect hippos from infections. Despite their largely aquatic lifestyle, hippos are not strong swimmers — they walk or run along the bottom of rivers and lakes.

Hippos are primarily herbivores that graze on grasses at night. They leave the water at dusk and can travel up to 10 kilometers in a single night to find enough grass to eat. An adult hippo can consume up to 35 kilograms of grass per night. During the day, they return to the water to rest and socialize. Hippos live in groups called pods or bloats, typically consisting of females and their young led by a dominant male.

Hippos are among the most aggressive and dangerous animals in Africa. Males establish and defend territories in the water, and they will aggressively charge anything they perceive as a threat — including boats and humans. Their large canine teeth, which can grow up to 50 centimeters long, are used as weapons during fights between males. Despite their reputation, hippos are not predatory — their aggression is defensive rather than driven by hunger.

The hippopotamus is classified as vulnerable to extinction due to hunting for its meat and ivory teeth, as well as habitat loss from human settlement and agricultural expansion. Hippos play an important role in their ecosystems — their waste fertilizes rivers and lakes, supporting the growth of algae and fish, which in turn feed other animals. Protecting hippo populations is essential for maintaining healthy African river ecosystems.

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