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Difference between Invertebrates and Vertebrates

In the animal kingdom, we can see the classification of the animals into two main categories on the basis of the presence or absence of the backbone or a spinal column. Besides this, there are many more differences between invertebrates and vertebrates. This article will explain the concepts with the difference between invertebrates and vertebrates. We will see and explore how these classes of organisms differ from each other. Insects and flatworms are examples of invertebrates whereas humans, birds, and snakes are some examples of vertebrates.

What Are Invertebrates?

We can simply identify the invertebrates as the animals which do not have the backbone. They can be found almost everywhere, even from the hottest deserts to the deepest seabed. And also from the darkest caves to the tallest mountains.

Thus, invertebrates are animals without the skeletal system. So, most of them do not possess a rigid body structure and hence they cannot grow very large. In terms of anatomically, most invertebrates have an open circulatory system where blood flows inside the open cavity. Most invertebrates are also possessing a simple respiratory system.

To compensate for this lacking of an internal skeleton, most invertebrates have an external skeleton to protect their soft, inner body. Such materials are usually made from chitin, a derivative of glucose. Invertebrates are constituting more than 95 percent of all species on the earth. Some main examples are annelids, arthropods, bivalves, coelenterates, echinoderms, squid, sponges, snails, and octopuses.

What are Vertebrates?

Vertebrates are the most advanced species in our animal kingdom. These animals are possessing a well-defined internal skeleton system including the backbone. In humans, the spinal cord runs in the body between the caudal and cranial regions and hence connecting the nerve tissues.

Vertebrates are having more complex and specialized organ systems if we compare with the invertebrates. Organ systems like the respiratory systems are very much complex due to many additional functions. Even the sensory organs present in vertebrates are advanced. And these are helping the vertebrates for adapting their respective environment.

On average, the overall count of vertebrates which are existing on the planet earth is around 57,000 to 58,000. Some main examples are mammals, birds, fish, reptiles, and amphibians, etc.

Difference between Invertebrates and Vertebrates

Difference between invertebrates and vertebrates

                                                                    Difference between invertebrates and vertebrates

The important difference between invertebrates and vertebrates

Parameters Invertebrates Vertebrates
Presence of Backbone They do not possess a backbone, not an internal skeleton. They possess a backbone and an internal skeleton.
Presence of exoskeleton Invertebrates are having an exoskeleton. Vertebrates are having the exoskeleton.
Body Size Generally, their body size is smaller than vertebrates. Generally, their body size is larger than invertebrates.
Circulatory system Almost all invertebrates possess an open circulatory system. All vertebrates are having a closed circulatory system.
Compound eye The majority of invertebrates have compound eyes. These don’t have compound eyes.
Body symmetry They have radial or bilateral body symmetry. They have bilateral body symmetry.
Population Almost 95% of animal species are invertebrates. Almost 5 % of animal species are vertebrates.
Nervous system These have a simple and unorganized nervous system. These have complex and highly specialized organ systems with specific functions.
Mode of nutrition It includes Autotrophic, Parasitic, and Heterotrophic. It is usually heterotrophic.

After seeing the difference between Invertebrates and Vertebrates in tabular form, let us have some more specific differences as follows:

  1. The difference on the basis of habitat:

Both types of animals live in many types of habitats. But, vertebrates can essentially suit themselves in any type of habitats easily. This is possible due to the nervous system and the internal skeletons of vertebrates.

  1. The difference on the basis of classification:

Vertebrates are being classified into fish, amphibians, reptiles, birds, and mammals. On the other hand, invertebrates include sponges, coelenterates, true jellies, sea anemones, sea pens, etc. Some more are echinoderms, worms, and arthropods, etc.

  1. Differences on the basis of size:

Size is one of the noticeable differences between invertebrates and vertebrates. Invertebrates like worms, shellfish, insects, etc. are small and slow-moving due to lack of solid support. Vertebrates are having a versatile support system, due to which they have the capability to develop faster and bigger bodies than invertebrates.

FAQs about Vertebrates and Invertebrates:

Q.1: Explain some characteristics of the invertebrates.

Answer: One of the main characteristics is the absence of a spinal cord. So, they lack a hard, bony internal skeleton. But, in some members, a hard, exterior structure called the exoskeleton is present. This also provides structural strength and protection from predators and the environment. Mostly they are motile, but there are exceptions like the sea sponge.

Q.2:  Explain some characteristics of the vertebrates.

Answer: Vertebrates are more complex organisms in comparison to the invertebrates. The main difference between these two is that vertebrates possess a backbone and a solid internal skeleton. Also, some vertebrates, are having bones replaced with the cartilage-like in sharks. One more defining characteristic of vertebrates is that they reproduce sexually.

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