Any animal that has a spinal cord is a chordate. This group covers most of the creatures you see at home or in zoos, and most of the meat and fish that you might eat, and it includes you, too. All chordates produce eggs which turn into babies.
The first chordates were fish that evolved from worms around 510 million years ago, in the Cambrian era. First they evolved long neurons that could carry signals from the brain to the tail more efficiently, and then they evolved bony vertebrae to protect those neurons. This turned out to be a successful strategy, so there got to be a lot of fish and other animals – like you – descended from fish.
These are some types of chordates:
- Amphibians (frogs)
- Reptiles (lizards, snakes, dinosaurs)
- Mammals (rats, dogs, cows, monkeys, giraffes, people)
Learn by doing: buy a whole fish, cook it, and carefully slice it open to find the vertebrae and the ribs. Or feel the vertebrae down a cat’s back.