How many people in your life have died of an infectious disease? Almost anyone answering that question before the 20th century would have said, "many."
Vaccinations, antibiotics, and hygiene have changed our lives. But the microbes are changing too. New diseases are emerging, as old ones evolve to resist the drugs that used to kill them. Take a look at the fight.
Comets are more than brilliant streaks of light in the night sky. These icy objects orbiting the Sun are actually fossils, rocky remnants from the early days of our solar system.
Discover how the comet’s coma and tail are formed and why Sun-grazing comets are important to astrophysics.
All living things have a need for food, water, shelter, and a place to raise young safely. The area that meets these needs is a habitat, which can be small or large.
Organisms that live in the same habitat form a community. Each plant and animal has a part to play there, known as its niche.
Toothed whales range in size from dolphins, porpoises, and orcas to sperm whales (at almost 60 feet long and 45 tons). There are about 65 species of toothed whales in the world.
Toothed whales are hunters, unlike the baleen whales that filter food through the baleen plates in their mouths. Also, toothed whales have one blowhole, while baleen whales have two.
When we’re born, we each have one half of the parts needed to produce another human being. But they’re not ready for reproduction until after we reach puberty, when female and male systems complete development. The human system is only one variation of sexual reproduction in the animal kingdom. Find out more.