Invertebrates lack the well- developed skeleton system, backbone, notochord as well nervous system whereas, Vertebrates constitutes, segmented, motile vertebral column together term as the spine, along with proper organized, nervous system, digestive system, gastrointestinal tract, respiratory system (which can be gills or lungs).
All the animals present on earth are classified in two categories only, which are Invertebrates or Vertebrates. Though it is said that Vertebrates arose from Invertebrates only, and it happened due to evolution and changes in the environment. But due to this Vertebrates have also developed themselves with the more advanced organization of body structure and more adjustable to all kind of environment, whether it is a sea, land or air.
Though Invertebrates have the simple structure, their size is small, compared to Vertebrates which may vary from small to the big one. But then too still Invertebrates mark their presence up to 98% of the total animal kingdom while Vertebrates occupy only 2%. Given below are the few points to compare Vertebrates with that of Invertebrates.
Content: Invertebrates Vs Vertebrates
|Basis for Comparision||Invertebrates||Vertebrates|
|Meaning||Animals without the backbone.||Animals with the backbone are called Vertebrates, their internal structure is made up of numerous bone.|
|Examples||Insects, roundworms, tapeworms, Sponges, Annelids.||Humans, elephant, birds, snakes, etc.|
|Characteristics||1.No cell walls.|
5. Heterotrophic (which depends on other for food) or Parasitic.
|1.Presence of backbone.
2.Cell walls present.
4.Advanced nervous system.
5.Well-developed internal skeleton.
6.The outer covering of protective skin.
|Size||Small and slow moving.||Vary in size from big to small.
|Body Symmetry||Radial or bilateral.||Only bilateral.|
|Body structure.||Simple and unorganised nervous system.||Complexed and highly specified organs and their functions.
|Layers of skin||They have only one layer of skin.||Two layers of skin, outer one in known is epidermis and beneath is dermis.|
|Type of Eyes||Usually, compound eyes are present and which are not outgrowth of the brain.||No compound eyes found and eyes are the outgrowth of the brain.|
|Their presence||98% of animal species are invertebrates, which identified and counted around 2 millions and much more are yet to be identified.||2% of the animal species are vertebrates, which are around 57,739 only.
Whenever we describe Invertebrates, the first thing comes into the mind is that they do not have the backbone and proper skeleton and nervous system. Invertebrates are small in size, and they covered around 98% of the total animal kingdom and rest 2% is covered by vertebrates. They can be found easily in water, desert, caves, soil, mountains. Invertebrates lack the developed organs and skeleton system due to which they don’t have a rigid structure of a body.
One of the major factor that invertebrates remain small in size due to lack of support system, loosely organized nervous system, and less growing muscles, which also make their motion slow. Annelids, Arthropods, Coelenterate are few examples of Invertebrates. However, Insects and Molluscs have outer skeleton system.
Other systems of a body like circulatory systems is open in many organisms and heart is dorsally placed, sometimes there is one opening for feeding and defections, a respiratory system is diverse and can be as simple as the diffusion process. They vary in their body symmetry like can be the radial or bilateral type of organization. The mode of feeding can be Parasitic or Heterotrophic.
Definition of Vertebrates
Vertebrates have the most advanced system of their body, which make them suitable to survive in a different environment. First and foremost vertebrates have well defined internal skeleton system consisting of numerous bones and are meant to functions differently. This skeletons system can be bony or cartilaginous. Vertebrates have other organs like respiratory system (gills and lungs), sensory organ and advanced nervous system too.
They have the systematic digestive system which includes parts from mouth to rectum; the Circulatory system is a closed one with heart located ventrally. Due to these reasons, their body allows them to fits into any environment right from sea to land as well air.
The special character of the vertebrates is the bilateral symmetrical body and brain covered by hard covering known as a skull. They have the mouth which opens anterior and used for feeding purpose mainly while defecation is through anus which opens posterior end of the body. Most vertebrates are heterotrophic i.e. they depend on other for their food. Examples include birds, reptiles, mammals, amphibians, and fish.
Key Differences Between Invertebrates and Vertebrates
Following are the key differences between Invertebrates and Vertebrates, which may be helpful to some extent in understanding them:
- The most remarkable difference between Invertebrates and Vertebrates is the presence of backbone, skull (outer covering of a brain) which is completely absent in Invertebrates and is well developed and proper functional in Vertebrates.
- Other features like the Nervous system, Respiratory system, Digestive system, Gastrointestinal tract and the Circulatory system is not so well developed and organized in Invertebrates as compared to Vertebrates.
- The body structure of Invertebrates is simple, with symmetry like radial or bilateral; Vertebrates have complex and organized body structure with only bilateral body symmetry.
- Above all still, Invertebrates registers their presence up to 98% of the total Animalia kingdom and much more to be identified, whereas Vertebrates occupies only 2% of the total Animalia kingdom.
Above we discuss the important points, by comparing the Invertebrate with Vertebrates, and hence we conclude that both types of animals are necessary for nature as they directly or indirectly dependent on each other for their survival. So the comparison was done just to know the various features and diversity of the organisms.