Understanding Vertebrates and Invertebrates

What is the primary characteristic that distinguishes vertebrates from invertebrates?

• Presence of a heart

• Presence of a skeleton

• Ability to swim

• Ability to fly

Which of the following is an example of an invertebrate with a hard skeleton?

• Octopus

• Slug

• Ant

• Worm

How do sea animals without a hard skeleton move?

• By using their bones

• By crawling

• By using a hydrostatic skeleton

• By flying

What does the term 'hydrostatic' refer to in the context of a hydrostatic skeleton?

• Air

• Fire

• Earth

• Water

What happens when the circular muscles of a sea animal contract?

• The animal becomes rounder

• The animal flies

• The animal shrinks

• The animal stretches