Scientists classify living things by grouping them based on shared physical characteristics. This system makes it easier to study relationships between species and identify new ones. As scientists learn more, these classification systems evolve to focus on body structures rather than just how organisms function.

1. Animal Classification: Vertebrates vs. Invertebrates

Animals are divided into two primary groups based on whether or not they have a backbone:

• Invertebrates (No Backbone): Make up the majority of animal species on Earth. Examples include insects, worms, jellyfish, snails, spiders, crabs, and sea stars.

• Vertebrates (Have a Backbone): Possess a spine made of vertebrae and internal skeletons that support movement and protect vital organs (like the brain and heart).

2. Plant Classification: Vascular vs. Nonvascular

Plants (organisms that produce their own food) are classified by how they transport water and nutrients:

Vascular Plants

Contain specialized tissue to transport water and nutrients throughout the plant. They are further grouped by how they reproduce:

• Seed Producers (with Flowers): Apple trees, roses, and flowering plants.

• Seed Producers (without Flowers): Pine trees and conifers.

• Non-Seed Producers: Ferns.

Nonvascular Plants

Lack transport tissues to move water and nutrients. Examples include mosses, liverworts, and hornworts.