Difference Between Invertebrates and Vertebrates, Key Examples

Aspect

Invertebrates

Vertebrates

Backbone

These animals do not have a backbone or vertebral column. e.g., worms, insects

These animals have a well developed backbone or spine., e.g., mammals, birds

Skeleton

They usually have an external exoskeleton made of chitin, while some may not have any skeleton at all.

They possess an internal skeleton made of bone or cartilage.

Body Size

Most of them are small in size, although some, like the colossal squid, can grow up to about 46 feet.

They are generally larger in size and have a strong body structure.

Circulation

They mostly have an open circulatory system where blood flows freely in the body cavity.

They have a closed circulatory system that allows efficient transport of blood.

Nervous System

Their nervous system is simple and less organized.

Their nervous system is complex and includes a brain and spinal cord.

Eyes

Compound eyes are commonly found, especially in insects and arthropods.

They do not have compound eyes and instead have advanced visual organs.

Symmetry

Their body symmetry can be radial or bilateral, as seen in starfish and insects.

Their body structure shows strictly bilateral symmetry.

Nutrition

They may follow autotrophic, parasitic, or heterotrophic modes of nutrition.

They mainly follow a heterotrophic mode of nutrition.

Diversity

Over 1.25 million species of invertebrates are found and are highly diverse.

This group includes around 62,000 species worldwide.

Examples

Sponges, arthropods, molluscs, etc.

Fish, amphibians, reptiles, birds, mammals, etc.