Classifying Animals

Vertebrates

Animals with a backbone that possess an internal skeleton made of bone or cartilage.

Invertebrates

Animals without a backbone, comprising approximately 95% of all animal species.

Mammals

Warm-blooded vertebrates that have hair or fur, nurse their young with milk, and typically give birth to live young.

Birds

Warm-blooded vertebrates with feathers, two wings, and beaks; they lay eggs with hard shells.

Reptiles

Cold-blooded vertebrates covered in dry, scaly skin or bony plates that breathe air using lungs and usually lay soft eggs.

Amphibians

Cold-blooded vertebrates with thin, moist skin that undergo metamorphosis from aquatic gilled larvae to terrestrial adults.

Fish

Cold-blooded vertebrates that live in aquatic environments, breathe through gills, and possess fins and scales.

Arthropods

The largest animal group, characterized by jointed legs, segmented bodies, and tough exoskeletons.

Mollusks

Soft-bodied invertebrates, many of which produce a hard shell for defense.

Annelids

Segmented worms with long, tube-like bodies divided into distinct segments.

Cnidarians

Simple aquatic creatures with stinging tentacles arranged around a central mouth.

Warm-blooded (Endothermic)

Animals that generate their own body heat and maintain a steady internal temperature.

Cold-blooded (Ectothermic)

Animals that rely on external sources to regulate their body temperature.

Exoskeleton

A rigid external covering that supports and protects an invertebrate's body.

Metamorphosis

The transformation an animal undergoes from an immature form to an adult stage.