Difference Between Vertebrates vs Invertebrates
Have you ever wondered how many living creatures there are on earth? The truth is, scientists strongly believe they have not encountered every single one of them, even though they have about 8.7 million of them on record. Because the numbers are so great, scientists came up with a system to help categorize and keep track of these creatures.
There are two main groupings we would like to discuss in this post. On a more specific note, we will take a look at the difference between vertebrates and invertebrates.
Definition of Vertebrates
Vertebrates are defined as animals with verified biological advancement characterized by endoskeletons that make up the back bones and perform other functions as well. To put it simply, they can be defined as creatures with backbones and other numerous bones.
The skeletal system is made of bones and cartilage. These well-advanced bone structures help them to survive in just about any environment – water, air, or land.
Aside from the skeleton, these creatures also have cell walls, advanced nervous systems, high organization ability, and a skull bone known as a cranium that houses a well-developed brain. Every creature in this category has several protective skin layers as well.
A feature that is particularly of interest in the invertebrate vs vertebrate comparison is their body symmetry. While the former has radial or bilateral symmetry, the latter has only bilateral symmetry. Also, 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 by a lack of backbone. They have no proper nervous or bone structures. Unlike in the other case where the skeleton is internal, members in this case have external skeletons known as exoskeletons. This category does not have developed bodies, are mostly small in size, and are mostly found in water bodies.
Scientists believe that their small size 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 slower because they do not have enough muscles to support their motion.
Interestingly, they do make up about ninety-eight percent of animals, 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 summarizing in simpler terms, the most common features that show how they vary from one another.
|Basis of Comparison
|Animals characterized by well-advanced and defined internal bones for different functions, including a structured backbone
|Animals that are characterized basically by the lack of backbones, proper nervous systems and skeleton
|Bilateral or radial symmetry
|Well-developed organs with designated functions. complex for the most part, with a well-organized nervous system
|Simple and unorganized nervous system
|Well-developed muscular system
|Multiple skin layers
|Single skin layer
|Makes up 2% in total
|Makes up 98% in total
|Type of eye
|No compound eyes
|Compound eyes present
|Mostly larger in comparison
|Mostly small in comparison
|Central nervous system
|A tube at the mid-dorsal line
|A hard tube at the mid-ventral line
|Structured beneath the outer layer
|Structured as the outermost layer
|Have a closed circulatory system
|Mostly have an open circulatory system
|A pair at least
|Two pairs in the very least
|Mammals, amphibians, birds, reptiles, etc.
|Worms, jelly fishes, sponge, arthropod, start fish, etc.
Difference Between Vertebrates and Invertebrates: Conclusion
In comparing these two major orderings – 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.