Animal Kingdom: MCQs Quiz – 10

> Reptiles have three-chambered heart with the exception of crocodiles. > All mammals are viviparous except monotremes. Monotremes are the only mammals that lay eggs. > Chordates have jaws except protochordates and cyclostomes.

The Phylum Porifera are the lowest multicellular animals belonging to kingdom animalia. In poriferans, the body is loose aggregate of cells (meshwork of cells). Internal cavities and canals are lined with food filtering flagellated cells i.e. choanocyte/collar cell. Choanocytes help in filter feeding.

In coelenterates, metagenesis is alternation of generation between polyp and medusa. Polyp reproduces asexually by budding to form medusa and medusa reproduces sexually to form polyp.

The Petromyzon (sea lamprey) is a migratory marine water jawless fish which shows anadromous migration. It spawns in fresh water, stops feeding and dies. Their ammocoete larvae, after metamorphosis, return to the ocean.

Trichinella spiralis is a nematode parasite occurring in men, found in skeletal muscles. It shows viviparity.

Chondrichthyes are group of fishes which shows features such as mouth is located ventrally, gill slits are separate and without operculum (gill cover), skin is covered with placoid scales and notochord remains persistent throughout life. (1) Organisms belonging to class Aves have dry skin without glands. Aves have dry skin, without glands except oil gland at the base of tail. (2) Pinnae are absent in aquatic and egg laying mammals. some aquatic mammals such as Sirenia does not possess external ear (3) Paired appendages are not found in ancestral vertebrates. In cyclostomes, unpaired appendages are present.

Platypus is oviparous (producing eggs rather than live babies).

The exoskeleton of insects is composed of hard chitin. Chitin contributes to the rigidity of the insect cuticle. Exoskeleton of insects is made up of chitinous cuticle which becomes hard due to deposition of calcium. It prevents desiccation and provides protection.

The taxon that represents both marine and freshwater species is cnidaria. Members of ctenophora, cephalochordata and echinodermata are exclusively marine.

Gorgonia (sea-fan) is an animal. All animals lack cell wall because they do not need them