are ammonotelic . Presence of well developed lateral line sense organ . Sexes are separate, external fertilization is seen and most forms are oviparous (Figure . ).
Examples: Exocoetus (Flying fish), Hippocampus (Sea horse), Labeo (Rohu), Catla (Catla), Echeneis (Sucker fish), Pterophyllum (Angel fish) . . Class: Amphibia (G. amphi -both; bios -life) Amphibians are the first vertebrates and tetrapods to live both in aquatic as well as terrestrial habitats.They are poikilothermic .
Their body is divisible into the head and trunk and most of them have two pairs of limbs; tail may or may not be present. Their . . Class: Chondrichthyes ( G.
chondros –cartilage; ichthys -fish) They are marine fishes with cartilaginous endoskeleton. Notochord is persistent throughout life. Skin is tough covered by dermal placoid scales and the caudal fin is heterocercal (asymmetrical both externally and internally). Mouth is located ventrally and teeth are modified placoid scales which are backwardly directed.
Their jaws are very powerful and are predaceous animals. Respiration by lamelliform gills without operculum (gill cover). Excretory organs are mesonephric kidneys. Two chambered heart is present.
Cartilaginous fishes are ureotelic and store urea in their blood to maintain osmotic concentration of body fluids. They are poikilothermic and viviparous . Sexes are separate. In males pelvic fins bear claspers to aid in internal fertilisation.
Examples: Scoliodon (Shark), Trygon (Sting ray), Pristis (Saw fish) (Figure . ). . .
Class: Osteichthyes (G. osteon –bone; ichthys -fish) It includes both marine and freshwater fishes with bony endoskeleton and spindle Figure . Examples of Osteichthyes Flying fish Sea horse Angel fish Carp Sucker fish Figure . Examples of Chondrichthyes Shark Pristis Sting ray XI Std Biology-Zoology Chapter- scutes.
Reptiles have three chambered heart but four chambered in crocodiles. All are cold blooded amniotes (poikilotherms). Most reptiles lay cleidoic eggs with extraembryonic membranes like amnion, allantois, chorion and yolk sac . Excretion by metanephric kidneys and are uricotelic.
Sexes are separate with well marked sexual dimorphism. Internal fertilization takes place and all are oviparous. Examples : Chelone (Turtle), Testudo (tortoise), Hemidactylus (House lizard), Chameleon (Tree lizard), Calotes (Garden lizard), Draco