The thyroid gland is a small, butterfly-shaped organ in your throat, and it secretes hormones that regulate the body's metabolism.
The Tasmanian tiger was the world's largest carnivorous marsupial. Recent unconfirmed sightings have spurred searches for this animal that was presumed extinct over 80 years ago.
Earth Day is an annual event, observed on April 22, that celebrates the planet's environment and raises public awareness about pollution.
Newts are small semi-aquatic amphibians that possess some interesting characteristics. For example, their skin is toxic and they can regenerate amputated limbs. "Astronewts" have also flown in space.
Gila monsters are the largest lizards native to the United States and one of only two venomous lizards in the world.
Warthogs, as the name implies, are related to pigs, and they have growths on their faces that look like warts.
Rabbits are small mammals with fluffy, short tails, whiskers and distinctive long ears. There are about 30 species of rabbits around the world.
Piranhas are South American fish with razor-sharp teeth and a reputation, somewhat undeserved, for feeding frenzies.
Porpoises have sleek bodies and large flippers, like their cousins the dolphins. But they are smaller and have different types of fins (or none at all).
Jackals are medium-size members of the dog family. They live primarily in Africa, and also in Europe and Asia.
Gophers are small, furry rodents that burrow tunnels through yards of North America and Central America.
Red pandas are small mammals with long, fluffy tails and red and white markings. They are not related to giant pandas.
Echidnas are walking contradictions. They are mammals, but they lay eggs. They are described as long-beaked and short-beaked, but they don't have beaks in the traditional sense.
Pangolins, also called scaly anteaters, are covered in hard, armor-like scales. These mammals are one of the most trafficked mammals in Asia and Africa, and are endangered.