Search results
Results from the WOW.Com Content Network
The trait that is common to all invertebrates is the absence of a vertebral column (backbone): this creates a distinction between invertebrates and vertebrates. The distinction is one of convenience only; it is not based on any clear biologically homologous trait, any more than the common trait of having wings functionally unites insects, bats ...
Vertebrates (/ ˈ v ɜːr t ə b r ɪ t s,-ˌ b r eɪ t s /) [3] are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain. The vertebrates make up the subphylum Vertebrata with some 65,000 species, by far the largest ...
Invertebrates represent 97% of all named animal species, [1] and because of that fact, this subdivision of zoology has many further subdivisions, including but not limited to: Arthropodology - the study of arthropods, which includes; Arachnology - the study of spiders and other arachnids; Entomology - the study of insects; Carcinology - the ...
It is traditionally considered as transitional fossil between invertebrates and vertebrates, [3] and considered as stem-group chordate in 2012. [4] [5] It was a primitive creature with no evidence of eyes, without a well defined head, and less than 2 inches (5 centimetres) long.
The vertebrates share one body plan, while invertebrates have many. This term, usually applied to animals, envisages a "blueprint" encompassing aspects such as symmetry, layers, segmentation, nerve, limb, and gut disposition. Evolutionary developmental biology seeks to explain the origins of diverse body plans.
[160] [162] [163] Humans and their livestock make up more than 90% of the biomass of all terrestrial vertebrates, and almost as much as all insects combined. [164] Invertebrates including cephalopods, crustaceans, insects—principally bees and silkworms—and bivalve or gastropod molluscs are hunted or farmed for food, fibres.
Research on invertebrates is the foundation for current understanding of the genetics of animal development. C. elegans is especially valuable as the precise lineage of all the organism's 959 somatic cells is known, giving a complete picture of how this organism goes from a single cell in a fertilized egg, to an adult animal. [3]
Marine invertebrates are animals that inhabit a marine environment apart from the vertebrate members of the chordate phylum; invertebrates lack a vertebral column. Some have evolved a shell or a hard exoskeleton. The earliest animals may belong to the genus Dickinsonia, [2] 571 million to 539 million years ago. [3]