Difference Between Vertebrates vs Invertebrates

Difference Between Vertebrates vs Invertebrates

If you were to start researching, you would be amazed at the variety of creatures that exist on earth. Scientists have discovered 8.7 million types of creatures, but even they cannot say for sure that they have come across every living thing on earth. Because the numbers are so great, scientists came up with a system to help categorize and keep record of them.

In this post, we will talk about the two categories of animals and the difference between vertebrates and invertebrates to be specific. We will explain what they are, their unique features, and how these two are different.

Definition of Vertebrates

Vertebrates are animals characterized by a well-advanced and defined internal skeletal system for different functions, including a structured backbone. To put it simply, they can be defined as animals with backbones and numerous other bones.

The skeletal structure is made of bones and cartilage. These advanced skeletal structures help them to survive in just about any environment including water, air, and land.

Aside from the skeleton, these animals also have cell walls and advanced nervous systems, features that are not available in the other case. They also have some special features like high organization, a well-developed brain bound by a bone known as the cranium, and an outer covering that consists of several protective skin layers.

Another outstanding quality that readily comes to view in any invertebrate vs vertebrate is their body symmetry. While the former has radial or bilateral symmetry, the latter has only bilateral symmetry. Their body structures differ in the sense that the former has a simple and unorganized nerve network, unlike the latter, which has complex and highly specified organs with various functions.

Definition of Invertebrates

Invertebrates are animals that are characterized basically by lack of backbones and proper skeletal or nervous systems. Unlike in the other case where the skeleton is internal, animals in this case have external skeletons, known as exoskeletons. This category of animals do not have developed bodies, are mostly small in size, and are mostly found in water bodies.

Scientists believe that the small size of these animals is a result of loosely organized nerve network and the lack of backbones, which means that they do not have a support system. In comparison, they are typically slower because they do not have enough muscles to support their motion.

Interestingly, these backboneless animals make up about ninety-eight percent of the animal kingdom, which is an obvious fact that points out the difference between invertebrates and vertebrates. They have just one layer of skin, no cell walls, and are either heterotrophic or parasitic in nature.

Main Differences Between Vertebrates vs Invertebrates

Here is a tabular representation of some of the differences between these major categories of animals.

Basis of ComparisonVertebratesInvertebrates
DefinitionAnimals characterized by an advanced and defined internal skeletal system for different functions, including a structured backboneAnimals that are characterized by the lack of backbones and proper skeletal or nervous systems
Body symmetryBilateral symmetryBilateral or radial symmetry
Body structureDeveloped organs with designated functions. Mostly complex with a well-organized nervous systemSimple and unorganized nervous system
MusclesWell-developed muscular systemLess-developed muscles
Skin layerMultiple skin layerSingle skin layer
Type of eyeNo compound eyesCompound eyes present
Central nervous systemA hollow tube at the mid-dorsal lineA solid tube at the mid-ventral line
Skeletal systemEndo-skeletal systemExo-skeletal system
Circulatory systemHave a closed circulatory systemMostly have open circulatory systems
LimbsMay have one or two pairs of limbsMay have more than two pairs of limbs
ExamplesMammals, amphibians, reptiles, birds, etc.Worms, jellyfishes, sponges, arthropods, starfish, etc.

Difference Between Vertebrates and Invertebrates: Conclusion

In comparing the two major classifications of animals on earth – vertebrates vs invertebrates, we have shared with you the differences that can help you tell them apart.

The presence of backbones and complex nervous systems in the former unlike in the latter is the most notable difference. Another difference can be seen in the number of limbs they have. The former has no more than two pairs of limbs, but the latter may have more than that.