Notochord, a flexible supporting rod along the back of an animal. It is present in all chordate animals at some stage in their development. A primitive chordate retains it throughout life. In higher vertebrate animals, the notochord is replaced before birth by a backbone.
Have you ever come home to find your dog waiting patiently for you at the front door? How did he know when to expect you? Do dogs have an understanding of time? Take our quiz to learn about how dogs perceive time.
Snakes can make you afraid and intrigued at the same time. Snakes have slithered over the Earth for more than 130 million years, frequently making appearances in famous narratives from the Bible to mythical stories. This unique animal can swallow animals whole and move across land without any limbs. Take this quiz and learn more about the mysterious snake.