Invertebrates And Vertebrates - Its Differences

In the animal kingdom, animals have been classified into two main categories invertebrate and vertebrate. This differentiation is mainly based on the presence and absence of the backbone or a spinal column. Apart from this, there are much more differences between this two animal categories.

Invertebrate And Vertebrate


Invertebrates can be simply identified as animals that don’t have a backbone. They are usually found in the desert, water,  water bodies, caves,  mountains. Invertebrates are the animals which mainly lack the skeleton system and other developed organs due to which they do not possess a rigid body structure. They consist of an open circulatory system and a simple respiratory system.

They hold more than 97 percent in the animal kingdom with many species of animals. There are more than 2 millions of Invertebrates existing on the planet earth.

For example, annelids, arthropods, bivalves, coelenterates, echinoderms, squid, sponges, snails, and octopus belongs to invertebrates.  There is some classification in invertebrates having external skeletons for insects and mollusks have. The lack of a supportive system, many invertebrates are smaller in size.


Vertebrates are the most advanced species of the animal kingdom. They are the animals with well defined internal skeleton system,  having a unique backbone. They consist of numerous bones. The spinal cord runs along the body between the caudal and cranial regions connecting to the nerve tissues.  Vertebrates have other organs like the respiratory system, sensory organ, systematic digestive system, well developed and an advanced nervous system too.

On an average, the overall count of vertebrates existing on the planet earth is around 57,000 to 58000.

Examples of vertebrate include the members of Chordates, mammals, birds, fish, reptiles, and amphibians. The main characteristics of the vertebrates have bilaterally symmetrical bodies and brain covered by the skull.

Differences Between Invertebrates And Vertebrates



Invertebrates do not possess a backbone. Vertebrates possess a backbone and an internal skeleton.
No cell walls, and are multicellular. Well-developed brain, Internal skeleton, and advanced nervous system.
 Small and slower-moving animals. Large and faster-moving animals.
Have an open circulatory system. Have a closed circulatory system.
Have compound eyes. Do not have compound eyes.
Includes radial or bilateral body symmetry. Includes only bilateral body symmetry.
Have a simple and unorganized nervous system. Have complex and highly specified organs with specified functions.
Composed of only one layer of skin. Composed of two layers of skin, dermis, and epidermis.
Mode of nutrition includes Parasitic or Heterotrophic. Mode of nutrition is usually heterotrophic.
95 to 98 percent of animal species are invertebrates. 2 to 3 percent animal species are vertebrates.
Flatworms, arthropods, sponges, insects are few examples Invertebrates. Mammals, fish, reptiles, amphibians, and birds are examples of Vertebrates.
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State whether true or false:
Rainforest is a homogenous habitat.