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.

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

Also Read: Symmetry in Animals – Definition, Types and Importance

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:

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

Also Read:

• Classification of Animals
• Diploblastic And Triploblastic Organization
• Levels of Organization in Animals