In this article we will discuss about Lampreys:- 1. Subject Matter of Lampreys 2. Habit and Habitat of Lampreys 3. External Structures 4. Skeletal Structures 5. Digestive System 6. Respiratory System 7. Circulatory System 8. Arterial System 9. Venous System 10. Nervous System 11. Excretory System 12. Reproductive System 13. Development. Contents: Subject Matter of Lampreys Habit and Habitat of [...]
In this article we will discuss about the modern concept on the phylogenetic status of cyclostomata. In this history of vertebrate evolution the cyclostomes occupy a doubtful status. Diverse opinions exist on the relative status of the cyclostomes in the vertebrate series. Cyclostomes are generally regarded to be lower in structural organisation than the fishes (Gnathostoma) but higher than Branchiostoma [...]
The swim-bladder in fishes and the lungs of tetrapods are closely similar in structure and development. Both these structures are intimately associated with the gut. The lungs of higher vertebrates arise exactly the same way as that of the swim-bladder in fishes. Both develop as outgrowths from the gullet and the glottis occupies exactly the same position. But the exact [...]