Difference between Invertebrates and Vertebrates

The difference between Invertebrates and Vertebrates is based on the presence of the backbone. Invertebrates makeup about 97% of all animal species, lack a backbone, and include diverse creatures such as insects, spiders, worms, mollusks, and crustaceans. On the other hand, vertebrates account for around 3% of the animal kingdom and possess a backbone made of bone or cartilage. This group comprises fish, amphibians, reptiles, birds, and mammals.

In this article, we will read about the differences between invertebrates and vertebrates and the similarities between Invertebrates and vertebrates.

Difference between Vertebrates and Invertebrates

What are Invertebrates? 

Definition: Invertebrates are a group of animals that do not possess a backbone or vertebral column.

Invertebrates account for about 97% of the whole animal kingdom. Invertebrates can be found in almost every habitat from marine environments to forests. This group includes insects, spiders, worms, molluscs, crustaceans etc. Some invertebrates like insects possess an exoskeleton, while others like worms lack one. These show two types of symmetry- radial and bilateral. Radial symmetry is found in starfish while bilateral symmetry is found in insects and spiders.

Reproduction can occur through both asexual and sexual means. Their circulatory system is open while some cephalopods such as squids and octopuses, have a closed circulatory system. They exhibit variation in sizes, from microscopic planktons to large arthropods such as the Japanese spider crab. Invertebrates are further classified into 9 Phylums- Porifera, Cnidaria, Platyhelminthes, Nematoda, Annelida, Arthropoda, Mollusca, and Echinodermata

What are Vertebrates? 

Definition: Vertebrates are a group of animals that possess a backbone or vertebral column.

Vertebrates include fish, amphibians, reptiles, birds, and mammals. The presence of an internal skeleton made of bone or cartilage is a characteristic feature of vertebrates. This structural framework not only supports the body but also protects vital organs. They generally exhibit bilateral symmetry. Their nervous system is highly developed. It is divided into the central nervous system which consists of the brain and spinal cord and the peripheral nervous system which has different types of nerves. 

Fish use gills while reptiles, birds, and mammals have lungs. Amphibians have both gills and lungs, thus adapting them to both aquatic and terrestrial environments. Most vertebrates reproduce sexually, with internal fertilization. They exhibit diverse reproductive strategies from external egg-laying in reptiles and birds to viviparity in mammals. Their circulatory system is closed. This closed system allows for more efficient transport of oxygen, nutrients, and waste products throughout the body. They exhibit a wide range of sizes, from small frogs to large whales. 

Difference between Invertebrates and Vertebrates

The table below gives us the points of difference between invertebrates and vertebrates:

Features	Invertebrates	Vertebrates
Backbone	Absent	Present
Skeleton	May or may not have an exoskeleton	Have an internal skeleton (bone or cartilage)
Symmetry	Radial or bilateral	Bilateral
Nervous System	Simple to well-developed	Highly developed
Respiration	Various methods (diffusion, gills, tracheal systems)	Gills, lungs, a combination of gills and lungs
Reproduction	Asexual and sexual	Primarily sexual
Circulation	Open or closed	Closed
Size	Wide range, from microscopic planktons to large arthropods	Wide range, from small frogs to large whales
Examples	Insects, spiders, worms, molluscs, crustaceans, etc.	Fish, amphibians, reptiles, birds, mammals

Similarities between Invertebrates and Vertebrates

We have understood that there are differences between Invertebrates and Vertebrates. But there are similarities also like:

• Both groups have the inbuilt mechanism of regulating temperature also known as homeostasis.
• Majority of the vertebrates and all invertebrates reproduce sexually.
• Both vertebrates and invertebrates show various adaptations and ability to evolve.

Conclusion – Difference between Invertebrates and Vertebrates

Vertebrates and Invertebrates are both major divisions of the animal kingdom. While all the organisms in vertebrates possess a backbone, the invertebrates do not possess one. Both divisions are classified on various features and are also different in those aspects such as symmetry, body organisation, reproduction mode. On the other hand, both organisms are eukaryotic in nature and also display the ability to adapt. Both the divisions play different ecological roles in the ecosystem and are equally important.

Difference Between Related Links

Difference Between Chordates and Non Chordates	Difference Between Bony Fish and Cartilaginous Fish
Difference Between Endoskeleton And Exoskeleton	Difference Between Oviparous and Viviparous Animals
Difference Between Coelomate and Acoelomate	Difference Between Pterodactyl and Pteranodon
Difference Between Spinal Cord and Backbone	Difference Between Sexual And Asexual Reproduction
Difference Between Open and Closed Circulatory System	Difference Between Cold Blooded And Warm-Blooded Animals

FAQs on Invertebrates and Vertebrates

What is the Main Difference between Invertebrates and Vertebrates?

The main difference is that invertebrates lack a backbone or vertebral column, while vertebrates have a backbone that provides support and protection.

Do Invertebrates have Organs?

Yes, they do have organs but most of them are not well developed like nephridia, malphigian tubules, etc.

What Types of Symmetry can be Found in Invertebrates?

Invertebrates can exhibit both radial symmetry (e.g., starfish) and bilateral symmetry (e.g., insects and spiders).

What is the Common Thing in Vertebrates and Invertebrates?

Few things that are found in both vertebrates and invertebrates is that they are both eukaryotic, multicellular and are heterotrophic. They can reproduce mostly sexually.

Why are Vertebrates Better than Invertebrates?

All the systems in vertebrates are more developed and specialised than invertebrates which allow them to survive in any kind of habitat.