Question

Which of the following is a correct sequence of decreasing order of the number of species?
A. Aves, Pisces, reptiles, amphibians, mammals
B. Pisces, aves, reptiles, mammals, amphibians
C. Pisces, mammals, reptiles, amphibians, aves
D. Amphibians, aves, Pisces, mammals, reptiles

Answer 1

Hint: The given species belong to the animal kingdom and the decreasing order of the number of species starts from fishes to frogs.

Complete answer: The class ‘Pisces’ are a diverse group in the vertebrates. They have a true jaw with specific organs that help in respiration, excretion and the blood circulation. They belong to the phylum Chordata and they cannot regulate their temperature, mostly it includes fishes; they are found in the freshwater or the brackish water, and their body distributed into the head, trunk, and tail. They swim with the help of their tail. They are classified into three types: Placodermi, Chondrichthyes and the Osteichthyes. The ‘Aves’ class belongs to the phylum Chordata that belongs to the animal kingdom. They can fly and show territorial behaviour. The birds are warm-blooded animals that have their forelimbs modified into wings and have flight muscles. They can hop, walk, grasp with the help of their hind limbs. Aves are classified into two categories that are; the Archaeornithes, who are extinct and the Neornithes; who have extinct as well as the extant birds. The reptiles are the first terrestrial animals, they belong to the phylum Chordata and the animal kingdom. They are cold-blooded animals and have scales on their body. The three types of reptiles are Anapsida, Parapodia, and Diapsida. Mammals are the most evolved species. They have mammary glands, which is an advanced characteristic that belongs to the class Mammalia and kingdom Animalia. They have three subclasses that are Eutheria, Metatheria, and Prototheria. The amphibians belong to the class Amphibia and phylum Chordata, They are the first cold-blooded animals on earth and can live on both land and water. Their body is divided into head and the trunk, whereas the tail may or may not be present. They are divided into three orders which include Apoda, Urodela, and Anura. The correct sequence of decreasing order of the number of species includes Pisces, aves, reptiles, mammals and amphibians.
Hence, the correct answer is option B.

Note: Whittaker proposed an elaborate five-kingdom classification: Monera, Protista, Fungi, Plantae and Animalia. The main criteria of the five-kingdom classification were cell structure, body organisation, mode of nutrition and reproduction, and phylogenetic relationships.