Why it is impossible to unequivocally answer the question about the number of species living on our planet.

Difficulties arise in the study of species due to their uneven distribution on the Earth (for example, in the tropical zone, the diversity is twice as high as in the temperate zone) and their habitat in places inaccessible to humans (for example, in oceanic depressions).
It is especially difficult to study small animals, such as, for example, some orders and families of ticks, spiders, insects, worms, etc. Entomologists (insect specialists) very often have to choose at first glance a very narrow field of activity, for example, to study beetles of which – Someone of the same genus or family.
The problem is also that in our time species disappear faster than they have time to detect and describe them.
When describing, often several species are described simultaneously by different scientists, give names, and after a while it turns out that this is the same species.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.