So: an additional day is added to the calendar cyclically – every four years. Someone likes this day, someone doesn’t like it, but it is necessary. Those who don’t like it can be comforted by the reminder that there is not a single essential four-cycle process in nature either.
Who does not know that there are four seasons: spring, summer, autumn, winter. They are related to the tilted axis of the Earth as it revolves around the Sun, thus the amount of heat and light that the Earth receives from the Sun.
The Earth’s natural satellite, the Moon, which rotates around our planet in a slightly elongated orbit, also has four phases related to its position relative to the Sun. As you know, there is a waxing moon, a full moon, a waning moon and a void moon. In general, the cycle of changing the phases of the moon runs for 29.5 days. Each phase lasts about one calendar week.
There are four phases of the day. The four-phase cycles of the day in nature mark changing units of time – night, morning, which in nature begins with sunrise, day and evening, which ends with sunset. Any cycle related to the Sun and the Moon ends and begins again. Continuously.
The cycles of biological or living nature are not so perfect, but they are also cyclical. Cycles involving living organisms are called substance and energy cycles. In nature, cyclicality is basically oriented towards the reproduction and development of beings.
What is this cycle?
Let’s take plants for example. As you know, they can be divided into annuals, biennials and perennials. And yet all plants have a similar – four-part (again four-part!) – life cycle. The life cycle of plants consists of four stages, each with its own functions, namely:
- the first – birth, or sprouting, or coming into the world;
- the second – development stage;
- the third and most important – reproduction or procreation stage;
- the last part of the cycle – death. Yes, death is also an integral part of the life cycle.
Not only plants, but also other organisms – lichens, algae, fungi and animals, including humans, basically have a similar – four-part – life cycle. True, for most species of animals it passes quickly. First of all, we are talking about those custodian species that produce only one generation of offspring per year. Not a few animal species produce two generations a year.
And there are also species that take care of the annual contribution of more than two generations. It is characteristic of some insects, arachnids. Among the creatures that nature has endowed with an exceptionally fast reproductive capacity, there is no shortage of agricultural and forestry pests.
Aphids, for example, stand out for their extremely skillful reproduction. Most of these insect species develop a large number of offspring per year. It is interesting that in the reproduction process of aphids, infertile generations usually alternate with fertile generations.
Laputis
Photo: Ilmārs Tīrmanis
In the summer, several successive parthenogenetic or asexual generations manage to develop. They are produced only by females that do not require fertilization and are viviparous for larvae. But it is also the turn of the sexual generations (males, females) to develop, because eggs must be produced. After all, the eggs laid by fertilized females are the stage that overwinters. In the following spring, the larvae hatch, which grow and develop into parthenogenetic females. It’s the annual cycle again.
There are animal species whose development – on the contrary – does not fit within one year, some even last for several years. Again, you have to turn to the insects. For example, a mayfly is a creature whose development period of one generation from an egg to an adult insect is usually four (!) years. Also, earthworms, unlike our other rightwings, develop slowly – usually these insects become capable of producing offspring only once in their life only in the third year of their life.
Earth cancer.
Photo: Freepik.com, VINICIUS SOUZA
Finally, it should be mentioned Ixodes genus pasture ticks, whose development in our climatic conditions usually takes an average of four years. For ticks, the duration of the development process is influenced to a certain extent by the ambient temperature, humidity and the availability of food, because before moving from one stage to the next, representatives of both sexes of these arachnids must eat – take blood every time. And fertilized adult females must eat again to successfully mature the eggs.
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2024-03-01 08:25:15
#Leap #year #February #cycles #nature
