(a) Similarities between aves and mammals

(i) The members of both the groups are homeotherms, i.e., warm blooded. They are able to maintain constant body temperature.

(ii) Heart is completely four chambered.

(b) Similarities between frog and crocodile

(i) The members of both the groups are poikilotherms, i.e., they lack the capacity to regulate their constant body temperature. They are cold blooded animals.

(ii) Frog and crocodile are oviparous animals.

(c) Similarities between turtle and Pila

(i) In both animals, body is covered with dry and cornified skin. In turtle, the epidermal covering is known as scales whereas in case of Pila, it is known as calcareous shell.

(ii) Both animals are oviparous.

(a) Ichthyophis does not possess limbs.

(b) Scoliodon (dog fish) is a cold blooded animal.

(c) Columba (pigeon) is a warm blooded animal.

(d) Naja naja (snake) possesses dry and cornified skin.

(e) Sycon (sponge) possesses canal system and bear spicules.

(f) Obelia bears cnidoblast.

(a) A viviparous animal is the one in which development of young ones is direct, later they provides nutrition to their offspring. It includes all mammals, except Platypus.

(b) A fish possessing a poison sting is Trygon (sting-ray). It is found on its tail. The poison released is strong enough to stun an animal.

(c) A fish possessing an electric organ Torpedo (electric ray). Electric organ in Torpedo is located in its big round pectoral fin which is just behind the eye. Large Torpedo can generate a fish killing current of up to 200 volts.

(d) An organ, which regulates buoyancy is air bladder present in class-Osteichthyes. (e.g., Exocoetus, Catla).

(e) Animal exhibiting alteration of generation is Aurelia or jelly fish of phylum-Cnidaria. It has two basic body forms called polyp and medusa are present. Polyp is sessile and cylindrical whereas medusa is umbrella shaped and free swimming form. Polyp produces medusa asexually and medusa forms polyps sexually (e.g., Obelia).

(f) Oviparous animal with mammary gland is Ornithorhynchus (duck-billed platypes). Duck bill platypus is the only mammal which lays egg and also bear mammary gland, which is a characteristic feature of mammals.

A. $\rightarrow$ (vi) B. $\rightarrow$ (ii) C. $\rightarrow$ (v) D. $\rightarrow$ (iii) E. $\rightarrow$ (vi) F. $\rightarrow$ (i)

A. Balanoglossus - Proboscis glands This gland present in front of central sinus and excretes brown granules.

B. Leech Nephridia It helps in osmoregulation and excretion.

C. Locust Malpighian tubules These tubules open into gut and help in excretion.

D. Liver fluke Flame cells They are specialised cells in Platyhelminthes which helps in osmoregulation and excretion. These are also called protonephridia.

E. Sea urchin-absent Specialised excretory organs are absent in sea urchin.

F. Pila-Metanephridia It is a type of excretory gland or nephridium found in many types of invertebrates such as annelids, arthropods, and molluscs (in molluscs nephridia is also known as Bojanus organ).

The major differences between Chordates and Non-chordates are as follows

Schematic sketch illustrating important characters of chordates is shown below