Zoology for UPSC and State PSC exams
Your blog category
Bony Fishes Cartilaginous Fishes Marine and Freshwater both Mostly marine Usually bilaterally flattened Usually dorsoventrally flattened Mouth is terminal on head Mouth is mostly ventral External nares are dorsal External…
Long, laterally compressed spindle shaped body tapering at both ends. 30 to 60 cm in length.Body surface is rough due to backwardly directed spines of placoid scales embedded in the…
Modified and degenerate offshoot of primitive vertebrate stalk, that arose in Devonian.In the adult stage, they are parasites or scavengers on fish. Secrete anti-coagulants in saliva to facilitate feeding on…
These are true, jawed vertebrates with specific organs for respiration, excretion and blood circulation. The organisms belonging to this class are poikilotherms, meaning that they cannot regulate their own body…
Features of VertebrataVertebral column or spine replaces the notochord.Cranium or skull that protects the brain. Cephalisation developed.Endoskeleton composed of bone or cartilage. Muscles are attached to the skeleton to provide…
— Lancelets (Amphioxus / Branchiostoma) General Features Exclusively marine animals, superficially like fish.Capable of swimming, but are usually buried in sand with only their anterior end exposed.Body small and fish…
Feature Urochordates Cephalochordates Examples Ascidia, Salpa, Doliolum Amphioxus (Branchiostoma) Adult Sedentary Free swimming Segmentation Absent Present Notochord Absent in adult Present Nerve Cord Absent in adult Present Coelom Absent Present…
Metamorphosis is a change from the juvenile to adult stage in which larval stage is quite different fromthe adult stage.In retrogressive metamorphosis the larva possesses advanced characters which are lost…
Body is divided into body proper and test.Free end of the body proper has 2 short cylindrical projections called branchial and atrial siphons. Atrial siphon is larger.The aperture to the…