Vertebrates vs Invertebrates
All the members of the animal kingdom include in these two groups, vertebrates and invertebrates. The differences between these two groups are umpteen. However, this article intends to discuss the most contrasting distinctions between the main body systems of vertebrates and invertebrates. By the sounds of the nomenclature, it means about the presence and absence of vertebrae in animals. For an example, diversity and distribution is very high in invertebrates, whereas the complexity, development, and specializations are high among vertebrates.
Vertebrate animals have their unique backbone with the spinal cord. The backbone is a column of vertebrae, which are parts of their internal skeleton. The skeleton could be either bony or cartilaginous. Among members of the Chordates, they are the largest group including Birds, Mammals, Fish, Amphibians, and Reptiles. Their spinal cord runs along the body between cranial and caudal regions with a hollow tube of nervous tissue called spinal cord. Vertebrates have a bilaterally symmetrical bodies. The most important feature of the vertebrates is the well-developed brain covered by the bony structure called skull. Their respiratory systems function with either lungs or gills for gas exchange between the animal and the environment. Sometimes, there are other gas exchanging surfaces viz. oral cavities and skins have been important, especially in amphibians. The vertebrate digestive system is a complete one starting at the mouth and ends after rectum. This gastro intestinal tract lies ventrally to the spinal cord. Additionally, the mouth opens anterior, and the anus opens from the posterior end of the body. The circulatory system is a closed one with a ventrally located heart. Those are the major characteristics of vertebrates.
Invertebrates are simply the animals without a backbone. Invertebrates are a large group of animals that consist of more than 97% of all the animal species with a broad collection of animals including many Phylas and Subphylas. Sponges, coelenterates, echinoderms, Annelids, Molluscs (Squid, Octopus, Snails, Bivalves), and Arthropods are all belong to invertebrates. Some invertebrates such as Insects and many Molluscs (mollusks) have external skeletons, while others do not. Because of the lack of a supportive system, most of the invertebrates are smaller. The nervous system is extremely diverse among invertebrates ranging from loosely organized hydra nerve net up to sophisticated cephalopod brains. Feeding in invertebrates is mostly parasitic as well as other heterotrophic habits, and their systems are very simple. Sometimes there is only one opening for both feeding and defecation. Circulatory systems are open in many instances, and the heart is dorsal. Their respiratory systems are extremely diverse that starts from simple diffusion. Invertebrates demonstrate both radial and bilateral symmetry in their body organization. All those discussed characteristics of invertebrates have great diversification among them.
What is the difference between Vertebrates and Invertebrates?
• Vertebrates have a backbone with a spinal cord, whereas invertebrates do not.
• The diversity is exceptionally high among the invertebrates compared to vertebrates.
• Vertebrates are always bilaterally symmetrical, while invertebrates could show either bilateral or radial symmetry.
• Vertebrates are usually large-bodied and move fast compared to invertebrates.
• Vertebrates have a closed blood system, a well-developed brain, either gills or lungs for respiration, and a complex and sophisticated nervous system, whereas those are primitive in invertebrates. Therefore, it concerns that vertebrates have many specializations to extract the best out of the environment compared to invertebrates.
Despite all these changes, someone could draw a point that invertebrates are more adaptive due to their simplicity, whereas vertebrates do not have a good adaptability in comparison because of the specialization. However, I would like to quote a popular quote to finish that in evolution specialization paralyses and ultra specialization kills the viability of taxons.