Animals
Animals are multicellular, eukaryotic organisms that form the kingdom Animalia. They are characterized by their ability to move, consume organic material for energy, and reproduce sexually. Animals display a wide range of adaptations for survival in diverse environments, and they play crucial roles in ecosystems as consumers, prey, and predators.
3 Key excerpts on "Animals"
eBook - ePubAnimal Locomotion
Physical Principles and Adaptations
- Malcolm S. Gordon, Reinhard Blickhan, John O. Dabiri, John J. Videler(Authors)
- 2017(Publication Date)
- CRC Press(Publisher)
...Living Animals are the current results of ongoing organic evolutionary experiments that nature has been pursuing since then. The most recent best estimates of the numbers of different kinds (species) of extant multicellular organisms (metazoans) included in the kingdom Animalia is 8.7 (±1.0) million (Costello et al. 2013). Evidence from the fossil record indicates that larger numbers of species lived for varying lengths of time in the past. Prebiotic evolution and the origin(s) of life are large active research areas. References providing entry into the rapidly growing literature include Anderson (1983), Dose (1988), Hogeweg and Takeuchi (2003), Markovitch and Doron (2013), Archibald (2014), Becker et al. (2016), Mesler and Cleaves (2016), and Olson and Straub (2016). The Cambrian explosion is also an area of active interest (Marshall 2006, Erwin and Valentine 2013, Smith and Harper 2013). Animals are classified by biologists as belonging to 32 major groups (phyla). Based on evidence from both the fossil record and from molecular phylogenies, many phyla have existed for very long periods (0.8+ Gy). Most of these groups have evolved substantially during these periods. Living representatives of at least some of these groups occur in almost every physical environment on Earth that has conditions compatible with water and carbon-based life forms. These environments range from the aquatic and subaquatic to the terrestrial (including subterranean) and aerial. Individual Animals range in size from microscopic to the blue whale (the largest animal that has ever lived). Excellent introductions to this biodiversity are Pechenik (2014) and Pough et al. (2013). This book is about selected aspects of the science deriving from study of current biodiversity and its evolutionary history. It begins with the recognition that nature is the designer, architect, engineer, builder, and manufacturer of life on Earth...
eBook - ePub- C. Lloyd (Conwy Lloyd) Morgan(Author)
- 2015(Publication Date)
- Perlego(Publisher)
...Cut a hydra into half a dozen fragments, and each fragment will become a perfect hydra. Reproduction of this kind is said to be asexual. We shall have, in later chapters, to discuss more fully some of the phenomena of reproduction and heredity. For the present, it is sufficient to say that Animals reproduce their kind by the detachment of a portion of the substance of their own bodies, which portion, in the case of the higher Animals, undergoes a series of successive developmental changes constituting its life-history, the special nature of which is determined by inheritance, and the result of which is a new organism in all essential respects similar to the parent or parents. 11. Animals are living organisms, and "not vegetables." The first part of this final statement merely sums up the characteristics of living Animals which have gone before. But the latter part introduces us to the fact that there are other living organisms than those we call Animals, namely, those which belong to the vegetable kingdom. It might, at first sight, be thought a very easy matter to distinguish between Animals and plants. There is no chance, for example, of mistaking to which kingdom an oak tree or a lion, a cabbage or a butterfly, belongs. But when we come down to the simpler organisms, those whose bodies are constituted by a single cell, the matter is by no means so easy. There are, indeed, lowly creatures which are hovering on the boundary-line between the two kingdoms. We need not discuss the nature of these boundary forms. It is sufficient to state that unicellular plants are spoken of as protophyta, and unicellular Animals as protozoa, the whole group of unicellular organisms being classed together as protista. The Animals whose bodies are formed of many cells in which there is a differentiation of structure and a specialization of function, are called metazoa, and the multicellular plants metaphyta...
eBook - ePubThis Is Biology
The Science of the Living World
- Ernst Mayr(Author)
- 1998(Publication Date)
- Belknap Press(Publisher)
...However, in certain areas, such as taxonomy and morphology, there remained a need to deal with Animals and plants separately. Development and physiology are, likewise, on the whole rather different in plants and Animals, and behavior concerns only Animals. No matter how brilliant the advances in molecular biology may be, there continues to exist a vital need for a biology of whole organisms, even though such a biology might have to be organized very differently from the traditional one. But aside from these exceptions, all biological problems concern plants and Animals equally. What is particularly interesting about the origin of the various new biological disciplines is that equivalent contributions were made by students both of plants and of Animals. The botanist Brown discovered the cell nucleus, and the botanist Schleiden with the zoologist Schwann proposed the cell theory, further developed by Virchow, who came from zoology and medicine. The problem of fertilization likewise was solved by a series of discoveries made by botanists and zoologists, and this is equally true for cytology and later for genetics. Numerous attempts have been made to develop a rational classification of all biological disciplines, to deal with the enormous range of phenomena brought together under the heading biology, but none of them has been entirely successful so far. Among all the classifications of biology that have been proposed over time, none has been more misleading than the one that recognized three branches of biology: descriptive, functional, and experimental. Not only were entire fields of biology (like much of evolutionary biology) virtually excluded by this classification, but it ignored the fact that description is a necessity in all parts of biology, and that the experiment is a major tool of analysis almost exclusively in functional biology...
