Question

The guano deposits are obtained from the excreta of
A. Reptiles
B. Human
C. Marine birds
D. Microorganisms

Answer 1

Hint: The word “Guano” is used to describe natural mineral sources or deposits. Guano deposits are very rich in nitrogen, phosphorus, and potassium, thus are very effective in plant growth and are used widely as natural fertilizers.

Complete answer:
Guano deposits are produced from the excreta, eggshells, and carcasses of certain organisms. Those organisms which excrete guanos are known as guanotelic organisms.
Guano deposits are mainly found in hot and dry climatic regions where rainfall is very less. Guanos are categorized according to their chemical composition, geographical origin, and age. The two major types of guano deposits are nitrogen and phosphate guanos. Phosphate guanos deposits are found in the calcareous soil, whereas the nitrogen deposits are found under specific tropical climatic conditions only. Guano deposits are non-toxic and generally insoluble.
Guano deposits are produced by marine birds (seabirds) and bats. Guano deposits produced by seabirds are rich in nitrate and ammonia. It has 8-20% nitrogen, of which 10% are in the form of proteins, 80% as uric acid, 7% as ammonia, and 0.5% as nitrate. They also contain phosphorus, calcium, and magnesium.

Thus the correct option is (C) Marine birds.

Additional information: Guanos have great ecological importance because of their high nutrient content. For example, cave ecosystems are completely dependent upon the guanos produced by bats, and they support the growth of many fungi, bacteria, invertebrates, and also some vertebrates. Thus, if the guano deposits become extinct, it will lead to the extinction of these organisms as well.

Note:
For over 2000 years, guano is being used as fertilizer for agriculture purposes. Its application as fertilizer started back in the 1840s in Europe and was popularly called as “guano boom”. Now-a-days, guano is replaced by industrially manufactured fertilizers.