Introduction Protostomes are one of the most diverse and abundant groups in the animal kingdom. Their distribution, variety, and abundance are largely the result of evolutionary adaptations to climatic changes in their respective environments. At present, they inhabit a wide range of terrestrial and marine environments. Many protostomes are familiar to most people, including spiders, […]
Ontogeny and phylogeny All animals must reproduce, passing copies of their genes into separate new bodies in future generations. These genetic copies may be genetically identical, produced by asexual processes, or genetically distinct, produced by sexual processes. In sexual processes, which are by far the more common among animals, the initial result of reproduction is […]