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Sleep can follow a physiological or behavioral definition. In the physiological sense, sleep is a state characterized by reversible unconsciousness, special brainwave patterns, sporadic eye movement, loss of muscle tone (possibly with some exceptions; see below regarding the sleep of birds and of aquatic mammals), and a compensatory increase following deprivation of the state, this last known ...
The majority of animal species are invertebrates; one estimate puts the figure at 97%. [1] Many invertebrate taxa have a greater number and diversity of species than the entire subphylum of Vertebrata. [2] Invertebrates vary widely in size, from 10 μm (0.0004 in) [3] myxozoans to the 9–10 m (30–33 ft) colossal squid. [4]
Many animals alternate between sleeping and waking in a daily cycle. Arousal and alertness are also modulated on a finer time scale by a network of brain areas. [8] A key component of the sleep system is the suprachiasmatic nucleus (SCN), a tiny part of the hypothalamus located directly above the point at which the optic nerves from the two ...
Invertebrate paleontology - the study of fossil invertebrates These divisions are sometimes further divided into more specific specialties. For example, within arachnology, acarology is the study of mites and ticks ; within entomology, lepidoptery is the study of butterflies and moths , myrmecology is the study of ants and so on.
A sleep disorder, or somnipathy, is a medical disorder of the sleep patterns of a person or animal. Polysomnography is a test commonly used for diagnosing some sleep disorders. Sleep disorders are broadly classified into dyssomnias , parasomnias , circadian rhythm sleep disorders (CRSD), and other disorders including ones caused by medical or ...
Free-running sleep is a rare sleep pattern whereby the sleep schedule of a person shifts later every day. [1] It occurs as the sleep disorder non-24-hour sleep–wake disorder or artificially as part of experiments used in the study of circadian rhythms and other rhythms in biology .
Modern groups of animals can be grouped by the arrangement of their body structures, so are said to possess different body plans. A body plan, Bauplan (pl. German: Baupläne), or ground plan is a set of morphological features common to many members of a phylum of animals. [1] The vertebrates share one body plan, while invertebrates have many.
Ectothermic animals also undergo periods of metabolic suppression and dormancy, which in many invertebrates is referred to as diapause. Some researchers and members of the public use the term brumate to describe winter dormancy of reptiles, but the more general term hibernation is believed adequate to refer to any winter dormancy. [ 8 ]