Search results
Results from the WOW.Com Content Network
Of these, the epicuticle is a multi-layered external barrier that, especially in terrestrial arthropods, acts as a barrier against desiccation. The strength of the exoskeleton is provided by the underlying procuticle, which is in turn secreted by the epithelial cells in the epidermis, [ 2 ] which begins as a tough, flexible layer of chitin .
Movement on appendages is the most common form of terrestrial locomotion, it is the basic form of locomotion of two major groups with many terrestrial members, the vertebrates and the arthropods. Important aspects of legged locomotion are posture (the way the body is supported by the legs), the number of legs, and the functional structure of ...
Illustration of the inferred size of the super-Earth CoRoT-7b (center) in comparison with Earth and Neptune. A Super-Earth or super-terran or super-tellurian is a type of exoplanet with a mass higher than Earth, but substantially below those of the Solar System's ice giants, Uranus and Neptune, which are 14.5 and 17.1 times Earth's, respectively. [1]
Transitional forms are seen as falling between the various groups in terms of anatomy, having a mixture of characteristics from inside and outside the newly branched clade. [ 7 ] With the establishment of cladistics in the 1990s, relationships commonly came to be expressed in cladograms that illustrate the branching of the evolutionary lineages ...
The model may show the anatomy partially dissected, or have removable parts allowing the student to remove and inspect the modelled body parts. Some models may have changeable genital inserts and other interchangeable parts which permit a unisex model to represent an individual of either sex.
Anatomy of an amniotic egg. Zoologists characterize amniotes in part by embryonic development that includes the formation of several extensive membranes, the amnion , chorion , and allantois . Amniotes develop directly into a (typically) terrestrial form with limbs and a thick stratified epithelium (rather than first entering a feeding larval ...
Model organisms are drawn from all three domains of life, as well as viruses. One of the first model systems for molecular biology was the bacterium Escherichia coli (E. coli), a common constituent of the human digestive system.
The 1944 accretion model by Otto Schmidt was further developed in a quantitative way in 1969 by Viktor Safronov. [4] He calculated, in detail, the different stages of terrestrial planet formation. [ 5 ] [ 6 ] Since then, the model has been further developed using intensive numerical simulations to study planetesimal accumulation.