Question

Which is the biggest phylum in regard to the number of species?
A. Protozoa
B. Platyhelminthes
C. Arthropoda
D. Chordata

Answer 1

Hint: They cover almost 80% of the total diversity of animals. They are small creatures but many. Their count can go in millions. It is a large phylum with many different species.

Complete solution:
The diversity of animals in our world is difficult to study if it is not organized. So. The hierarchical classification method was proposed to place them in groups following their features. The rankings are Kingdom, Phylum, Order, Family, Genus and species. As we go down the hierarchy the specification increases, but the number of species in group decreases.

There are 36 recognized phyla but 9 are the mast described ones. They are porifers, Platyhelminthes, Mollusca, cnidaria, nematode, annelid, Arthropoda, Echinodermata, and Chordata.

Let us see the number of species in the phylum mentioned in the question.
> Option A- Protozoa: They are the simplest creatures present on earth. There are more than 50000 species recorded under this category.
> Option B- Platyhelminthes: They have the Flatworms, scavengers, parasites in them. There are about 25,000 species under this phyla.
> Option C- Arthropoda: They mostly consist of insects, crustaceans, arachnids etc. They cover almost 80 per cent of the animals. The number can go to 8,00,000. This forms the largest phyla of all the others.
> Option D- Chordata: They include sea squirts, sea salp, mammals, reptiles, amphibians etc. with more than 50,000 species. This is also a large phylum. They have vertebrates- animals with a backbone.

So the answer is option C: Arthropoda

Note: Whittaker gave the hierarchical classification method. Taxonomic classification was given by Carl Linnaeus. He explained the method of naming and organizing these species. Both these methods became very helpful in handling this huge data.