Early Modern Era In the
early modern period starting in the late 16th century, invertebrate zoology saw growth in the number of publications made and improvement in the experimental practices associated with the field. (Insects are one of the most diverse groups of organisms on Earth. They play important roles in ecosystems, including pollination, natural enemies, saprophytes, and biological information transfer.) One of the major works to be published in the area of zoology was
Conrad Gessner's
Historia animalium, which was published in numerous editions from 1551 to 1587. Though it was a work more generally addressing zoology in the large sense, it did contain information on insect life. Much of the information came from older works; Gessner restated the work of
Pliny the Elder and
Aristotle while mixing old knowledge of the natural history of insects with his own observations. With the invention of the
Microscope in 1599 came a new way of observing the small creatures that fall under the umbrella of invertebrate.
Robert Hooke, who worked out of the Royal Society in England, conducted observation of insects—including some of their larval forms—and other invertebrates, such as ticks. His
Micrographia, published in 1665, included illustrations and written descriptions of the things he saw under the microscope. Others also worked with the microscope following its acceptance as a scientific tool.
Francesco Redi, an Italian physician and naturalist, used a microscope for observation of invertebrates, but is known for his work in disproving the theory of
spontaneous generation. Redi managed to prove that flies did not spontaneously arise from rotting meat. He conducted controlled experiments and detailed observation of the fly life cycle in order to do so. Redi also worked in the description and illustration of parasites for both plants and animals. Other men were also conducting research into pests and parasites at this time.
Felix Plater, a Swiss physician, worked to differentiate between two types of tape worm. He also wrote descriptions of both the worms he observed and the effects these worms had on their hosts. Swammerdam also worked on a classification of insects based on life histories; he managed to contribute to the literature proving that an egg, larva, pupa, and adult are indeed the same individual.
18th and 19th centuries In the 18th century, the study of invertebrates focused on the naming of species that were relevant to economic pursuits, such as agricultural pests. Entomology was changing in big ways very quickly, as many naturalists and zoologists were working with hexapods. Work was also being done in the realm of
parasitology and the study of worms. A French physician named
Nicolas Andry de Bois-Regard determined that worms were the cause of some diseases. He also declared that worms do not spontaneously form within the animal or human gut; de Bois-Regard stated that there must be some kind of 'seed' which enters the body and contains the worm in some form. Linnaeus' universal system of classification made a system based on
binomial nomenclature, but included higher levels of classification than simply the genus and species names.
Systema Naturae was an investigation into the
biodiversity on Earth. The book also included descriptions of the organisms named inside of it. In addition, Darwin collected many species of invertebrate during his time aboard ; many of the specimens collected were insects. Using these collections, he was able to study
sexual dimorphism, geographic distribution of species, and
mimicry; all of these concepts influenced Darwin's theory of evolution. Unfortunately, a firm popular belief in the immutability of species was a major hurdle in the acceptance of the theory.
20th century Classification in the twentieth century shifted toward a focus on evolutionary relationships over morphological description. The development of
phylogenetics and systematics based on this study is credited to
Willi Hennig, a German entomologist. In 1966, his
Phylogenetic Systematics was published; inside, Hennig redefined the goals of systematic schemes for classifying living things. He proposed that the focus be on evolutionary relationships over similar morphological features. He also defined
monophyly and included his ideas about hierarchical classification. Though Hennig did not include information on
outgroup comparison, he was apparently aware of the practice, which is considered important to today's systematic research. ==Notable invertebrates==