Vertebrates are animals that have a backbone inside their body. The major groups include fish, amphibians, reptiles, birds and mammals.
Invertebrates don’t have a backbone. They either have a soft body, like worms and jellyfish, or a hard outer casing covering their body, like spiders and crabs.
| ELEMENTS OF COMPARISON | VERTEBRATES | INVERTEBRATES |
| Description | Vertebrates are animals that have a bony or cartilage vertebral column. | Invertebrates are animals that do not have a backbone or a vertebral column. |
| Body Size & Movement | Generally large and fast-moving animals. | Generally small and slow-moving animals. |
| Classification | There are only five classes of vertebrates. | There are thirty different classes of invertebrates. |
| Breathing | They breathe through either gills or lungs. | They have many ways of breathing, some use spiracles; some can pass oxygen through their skin while others have primitive ‘book’ lungs. |
| Notochord | A notochord is present | A notochord is absent is absent. |
| Central Nervous System (CNS) | Their central nervous system is a hollow tube, which is located in the mid-dorsal line. | Their central nervous system is a solid tube, which is located in the mid-ventral line. |
| Population Percentage On Earth | They comprise only 2-3% of the total animal species found on Earth. | They comprise more than 90% of the total animal species found on Earth. |
| Endoskeleton & Exoskeleton | They have a living endoskeleton made up of bones and cartilage. | Some have a hard non-living exoskeleton or shell. |
| Temperature Regulation | They are warm-blooded animals. Their body temperature remains constant. It does not vary with the temperature of the outside environment. | They are cold-blooded animals. Their body temperature varies with the outside temperature and remains equal to the outside temperature. |
| Layers Of Skin | They are composed of two layers of skin: dermis and epidermis. | They are composed of one layer of skin. |
| Location Of Heart | Their heart is located on the ventral side of the body. | Their heart is located on the ventral side of the body. |
| Nervous System | They tend to have a complex nervous system and highly specified organs with specific functions. | They tend to have a simple and unorganized nervous system. |
| Red Blood Cells (RBC) | They have red blood cells which contain hemoglobin. | They do not have red blood cells. Their respiratory pigments occur in the blood plasma. |
| Appendages | They do not have more than two pairs of limbs. | They can have more than two pairs of appendages. |
| The Eyes | The eyes of the vertebrates occur as an outgrowth from the brain. | The eyes of the invertebrates occur as an outgrowth of the skin. |
| Type Of Eyes | Most vertebrates have simple eyes. | Most invertebrates have compound eyes. |
| Sex | All vertebrates are unisexual animals. | Most invertebrates including sponges, worms, snail and slugs are hermaphroditic animals. |
| Circulatory System & Body Symmetry | Have a closed circulatory system with only bilateral body symmetry. | They have an open circulatory system with radial or bilateral body symmetry. |
| Mode Of Nutrition | Their mode of nutrition is usually heterotrophic. | The mode of nutrition includes parasitic and heterotrophic. |
| Pharyngeal Clefts | The pharynx of vertebrates has pharyngeal clefts to increase the efficiency of breathing. | Invertebrates do not have pharyngeal clefts. |