Zoology

Amphibians are cold blooded vertebrates. In the Devonian period of palaeozoic era they were originated…
Amphibians are the earliest tetrapods. They were descended from fish like ancestors. They were developed…
On the upper and lower surfaces of the head a number of tin- branched structures…
It lies in the auditory capsule of the skull. It is useful for maintenance of…
In male shark claspers are present. The claspers are rod like copulatory organs present on…
In Scoliodon the olfactory lobes are olfactory organs or nasal sacs.   They are present…
On the lateral sides of think and tall lateral line canals are present. They are…
The super class Gnathostomata includes craniates, in which one pair of the visceral arches is…
Fishes are first evolved in silurian period of palaeozoic era. They increased their number in…
Ammocoetes Larvae: Matamorphosis   In the life history of Petromyzon a larval form is seen.…
Branchial Basket   In Petromyzon the visceral skeleton contains branchial basket. It lies external to…
Myxine (Hagfish) Petromyzon (Lamprey) 1. Hag fishes are scavengers. They penetrate into the dead fishes…
The class Cyclostomata is divided into two orders:1) Petromyzonia and 2) Myxinoidea   Order 1:…
Cyclostomes’ are jawless vertebrates. They are primitive vertebrates. The cyclostomes are marine or fresh-water vertebrates.…
SUB-PHYLUM VERTEBRATA is further divided into two super-classes.   AGNATHA, AND GNATHOSTOMATA.   SUPER-CLASS 1.…
Vertebrates show the following characters, besides the chordate characters.   1. PRESENCE OF ENDO AND…
LARVAE OF PORIFERA Parenchymula (Stereo- gastrula) - Leucosolenia Rhagon - Higher sponges Amphiblastula - Sycon…