Differences between Vertebrados- and Invertebrados
Contents
Vertebrados and invertebrados[edit]
Animals are categorized into two primary groups based on the presence or absence of a vertebral column: vertebrates and invertebrates. This classification, though historically significant, distinguishes a single subphylum of animals from a diverse collection of more than 30 other phyla. Vertebrates belong to the subphylum Vertebrata within the phylum Chordata. Invertebrates constitute all other animal life, representing approximately 97% of all described species [1].
Comparison table[edit]
| Feature | Vertebrados | Invertebrados |
|---|---|---|
| Backbone | Present (vertebral column) | Absent |
| Skeleton type | Internal endoskeleton | Exoskeleton or hydrostatic skeleton |
| Nervous system | Dorsal hollow nerve cord | Ventral or decentralized nerve net |
| Symmetry | Exclusively bilateral | Radial, bilateral, or asymmetrical |
| Circulatory system | Closed system with a ventral heart | Open or closed systems; heart position varies |
| Respiratory system | Gills or lungs | Tracheae, book lungs, or skin diffusion |
| Relative diversity | ~3–5% of animal species | ~95–97% of animal species |
| Average body size | Generally larger | Generally smaller |
Structural support and skeletal systems[edit]
The most distinct difference between the two groups is the method of bodily support. Vertebrates possess an endoskeleton composed of bone or cartilage. This internal structure grows in proportion with the animal, allowing for continuous development and the attainment of large physical sizes. The vertebral column protects the spinal cord and provides an attachment point for muscles, which facilitates complex movement [2].
In contrast, invertebrates utilize several different support mechanisms. Many species, such as those in the phylum Arthropoda, possess an exoskeleton made of chitin. This hard outer shell must be shed and replaced through a process called ecdysis to allow the animal to grow. Other invertebrates, such as annelids and cnidarians, rely on a hydrostatic skeleton, which uses internal fluid pressure to maintain shape and enable locomotion. Some groups lack hard structures entirely [3].
Physiological and nervous systems[edit]
Vertebrates exhibit a highly centralized nervous system. This includes a brain encased in a cranium and a dorsal nerve cord. The circulatory system in vertebrates is closed, meaning blood remains within vessels, and oxygen is transported by hemoglobin. A muscular heart located ventrally pumps blood through the body.
Invertebrate physiology is more varied. The nervous systems of many invertebrates, such as insects and crustaceans, consist of a ventral nerve cord and a series of ganglia. Some primitive invertebrates, like jellyfish, use a decentralized nerve net. Circulatory systems among invertebrates are often open, where hemolymph fills the body cavity to bathe organs directly. Exceptions include cephalopods and earthworms, which possess closed circulatory systems.
Diversity and distribution[edit]
The group labeled as invertebrates encompasses a wider range of body plans and taxonomic variety than vertebrates. Invertebrate phyla include Porifera (sponges), Mollusca (snails and squid), and Echinodermata (starfish). Vertebrates are limited to fish, amphibians, reptiles, birds, and mammals. While vertebrates often occupy the highest levels of food chains, invertebrates are essential for processes such as pollination, decomposition, and soil aeration [1].
