Final answer:
The fundamental difference between vertebrates and invertebrates lies in the presence of a backbone; vertebrates have a backbone, while invertebrates do not. Other differences include the presence of an exoskeleton in invertebrates, variations in circulatory and nervous systems, and size. Vertebrates also belong exclusively to the phylum Chordata, which includes some invertebrates as well.
Step-by-step explanation:
Differences Between Vertebrates and Invertebrates
Vertebrates and invertebrates represent two very different groups of animals, with several distinct differences between them.
- Backbone: Vertebrates have a backbone (vertebral column) made of bone or cartilage, while invertebrates lack a backbone altogether.
- Exoskeleton: Invertebrates may have an exoskeleton, which is a rigid external covering for the body that provides both support and protection. Vertebrates do not have exoskeletons.
- Symmetry: Both groups can exhibit various forms of symmetry, though bilaterally symmetrical body plans are most common.
- Circulatory System: Vertebrates generally have a closed circulatory system, including a heart, whereas invertebrates can have either an open or closed system, and some lack a circulatory system entirely.
- Nervous System: The nervous systems of vertebrates are more complex and centralized, featuring a brain and spinal cord, in comparison to invertebrates, whose nervous systems can vary greatly in complexity.
- Mode of Nutrition: Both vertebrates and invertebrates can be found across a spectrum of nutritional lifestyles, including herbivory, carnivory, and omnivory.
- Size: Vertebrates include some of the largest animals on the planet, whereas invertebrates, while varying greatly in size, generally do not reach the sizes of the largest vertebrates.
- Eyes: The complexity and structure of eyes can vary greatly within both vertebrates and invertebrates, from simple light-sensitive eye spots to complex structures with lenses and retinas.
Examples: Examples of vertebrates include fish, amphibians, reptiles, birds, and mammals. Examples of invertebrates include insects, earthworms, jellyfish, and many other species.
Collectively, invertebrates make up at least 95 percent of all animal species, significantly outnumbering vertebrates. The phylum Chordata, to which all vertebrates belong, also contains invertebrates like tunicates and lancelets. This illustrates that not all chordates are vertebrates, but all vertebrates are chordates.