Alligators and Crocodiles — Reading Comprehension Lesson

Reading Passage

Alligators and Crocodiles

Alligators and crocodiles are large, semi-aquatic reptiles that belong to the order Crocodilia. They are among Earth’s oldest surviving animal lineages, having changed very little since they shared the planet with non-avian dinosaurs more than 80 million years ago. Today, 23 species of crocodilians are found on every continent except Europe and Antarctica, inhabiting tropical and subtropical freshwater and saltwater environments. They are apex predators in many ecosystems, playing important roles in maintaining ecological balance.

Despite their similarities, alligators and crocodiles are not the same animal. The easiest way to tell them apart is by their snout shape and teeth. Alligators have a wide, rounded, U-shaped snout, and when their mouths are closed, their teeth are mostly hidden. Crocodiles have a longer, more pointed, V-shaped snout, and the fourth tooth on each side of their lower jaw is visible even when their mouths are shut. Alligators are generally darker in color and live only in the southeastern United States and China. Crocodiles are found throughout the tropics of Africa, Asia, Australia, and the Americas.

Crocodilians are highly effective predators despite appearing slow and lethargic. They can remain motionless for hours, submerged with only their eyes and nostrils above water, waiting for prey to approach. When prey comes within range, they lunge with explosive speed, using their powerful jaws — which can exert the strongest bite force of any animal — to seize it. They then drag it underwater or use a spinning motion called the “death roll” to tear off chunks of meat. Despite this fearsome reputation, crocodilians feed only a few times per week and their metabolic rate is much lower than that of mammals.

Crocodilians are surprisingly attentive parents for reptiles. Females build nests of vegetation or dig holes in sandy riverbanks in which they lay clutches of 20 to 80 eggs. They guard their nests fiercely and help their hatchlings emerge from the eggs when they hear the young calling. Mothers carry their hatchlings to the water in their mouths and protect them for months or even years. This parental care significantly improves survival rates. American alligators are a conservation success story: once hunted nearly to extinction, they were protected by the Endangered Species Act and their populations have rebounded dramatically.

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