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The behavior of an amphibian hatchling, commonly referred to as a tadpole, is controlled by a few thousand neurons. [4] 99% of a Xenopus hatchling's first day after hatching is spent hanging from a thread of mucus secreted from near its mouth will eventually form; if it becomes detached from this thread, it will swim back and become reattached, usually within ten seconds. [4]
A hatchling still possesses a yolk sac upon which it depends for nutrition, and are thus also known as a sac fry. Fry – refers to a more developed hatchling whose yolk sac has almost disappeared, and its swim bladder is functional to the point where the fish can move around and perform limited foraging to nourish itself. [4]
Extremely precocial species are called "superprecocial". Examples are the megapode birds, which have full-flight feathers at hatching and which, in some species, can fly on the same day. [3] Enantiornithes [4] and pterosaurs [citation needed] were also capable of flight soon after hatching.
The form comes with two worksheets, one to calculate exemptions, and another to calculate the effects of other income (second job, spouse's job). The bottom number in each worksheet is used to fill out two if the lines in the main W4 form. The main form is filed with the employer, and the worksheets are discarded or held by the employee.
The theory of recapitulation, also called the biogenetic law or embryological parallelism—often expressed using Ernst Haeckel's phrase "ontogeny recapitulates phylogeny"—is a historical hypothesis that the development of the embryo of an animal, from fertilization to gestation or hatching (), goes through stages resembling or representing successive adult stages in the evolution of the ...
These chemicals block the conversion of testosterone to estradiol during development so each sex offspring can be produced at all temperatures. They found that hatching temperatures that naturally produce each sex maximized fitness of each sex, which provides the substantial empirical evidence in support of the Charnov & Bull model for reptiles ...
The traditional modes of reproduction include oviparity, taken to be the ancestral condition, traditionally where either unfertilised oocytes or fertilised eggs are spawned, and viviparity traditionally including any mechanism where young are born live, or where the development of the young is supported by either parent in or on any part of their body.
This glossary of biology terms is a list of definitions of fundamental terms and concepts used in biology, the study of life and of living organisms.It is intended as introductory material for novices; for more specific and technical definitions from sub-disciplines and related fields, see Glossary of cell biology, Glossary of genetics, Glossary of evolutionary biology, Glossary of ecology ...