Activity Cycle

Activity Cycle


a term in biology denoting periodic variations in animal mobility and behavior in connection with alteration (seasonal, daily) of living conditions and oscillations of metabolic intensity which result from such oscillations. The activity cycle is one manifestation of biological rhythms, which are inherent in all organisms. The seasonal activity cycle, associated with variation in day length, temperature curve, humidity, food supply, and the like, determines the periodicity of reproduction, animal and bird migrations, food storing, and fat accumulation. Certain land mammals and nearly all cold-blooded animals go into hibernation during the cold months of the year. Daily activity cycles result from changes in temperature, illumination, and other factors; with these are associated daily migrations of animals (this is characteristic mainly of plankton, soil organisms, and a few others). On the basis of type of daily activity, animals can be classed as diurnal, nocturnal, crepuscular, and around the clock. Variations in the activity cycle are not uncommon; many animals lead a diurnal existence during winter and a nocturnal existence during summer.


Kalabukhov, N. I. “Sutochnyi tsikl aktivnosti zhivotnykh.” Uspekhi sovremennoi biologii, 1940, vol. 12, no. 1.
Biologicheskie chasy. Moscow, 1964. (Collection of articles translated from English.)


References in periodicals archive ?
The SCN is a small region inside the hypothalamus which regulates a 24hours rest and activity cycle and helps animals know when they should eat or rest.
In fact, we think it happens every 22 years as part of the Sun's major activity cycle, with the North and South Poles of the Sun's "bar magnet" swapping ends and the magnetic fields associated with them causing an increase in solar activity.
Based on these data, Wolfgang Gleissberg suggested in 1939 that there could be a roughly 100-year cycle superimposed on the 11-year activity cycle.
The frequency with which these phenomena occur varies in a somewhat irregular activity cycle of about 11 years, during which the global magnetic field of the Sun reverses.
Flares are cropping up quite often in recent months, as the sun is nearing the maximum point of its 11-year activity cycle.
In other words, if there is a total of four activities, the activity cycle will have four unit modules, such as "B" or "C" in Fig.
Increased numbers of flares are quite common at the moment, since the sun's normal 11-year activity cycle is ramping up toward solar maximum, which is expected in 2013.
The atlas is rich in detail, with color distribution maps, color photos of the species, and lengthy entries that include sections on taxonomy, distribution, habitat, altitudinal distribution, annual activity cycle, reproduction, and status, along with commentary.
His finding show that the sun's activity cycle will soon reverse and the Earth's temperatures will decrease between 2012 and 2015 which could lead to a deep freeze around 2055-2060, and that it could last for at least 50 years.
The Third Overall Performance Study of the GEF (OPS3) and the joint evaluation of the GEF activity cycle identified a number of further improvements that could be made to the fundamental design and functioning of the STAP.
But they will both rest and restrict their activity cycle this week in order to recuperate.