What are 'invertebrates'?

What are 'invertebrates'?

Marc Grover (Professional Aquarist) gives expert video advice on: What plants are best for my freshwater aquarium?; How do I choose a healthy plant for my aquarium?; What kind of lighting will my aquarium plants need? and more...

You can have invertebrates in both salt water and fresh water and it basically means without a backbone, without a spine. Shrimp, lobster, crabs, feather dusters, things that either have no internal skeleton or their skeleton is on the outside. Mostly, it's no internal skeleton.