1. Describe evolutionary perspective of fishes.
  2. Describe phylogenetic relationships of fishes.
  3. Discuss whether evolution of fishes takes place in marine or fresh water environment.
  4. Give characters of Agnathans. Name its different classes with examples.
  5. What are ostraeoderms? What is their evolutionary importance?
  6. Write note on Hag fishes.
  7. Describe the life cycle of sea lamprey.
  8. Write note on Gnathostomes. Name their classes.
  9. Write not on Ammocoete larvae.
  10. Write not on sharks.
  11. What are skates and rays?
  12. Write note on Holocephalans.
  13. Write note on lung fishes. Discuss their role in evolution of land vertebrates.
  14. Write not on Coelacanths.
  15. Write not on Subclass Actinopterygii.
  16. What are Chondrosteans?
  17. What are Actinopterygians? Discuss their importance in fishes.
  18. Discuss locomotion in fishes.
  19. Describe nutrition in fishes.
  20. Discuss blood circulation in fishes.
  21. Describe the mechanism of gas exchange in fishes.
  22. What is the role of swim bladder in the evolution of lungs?
  23. How is buoyancy regulated in fishes?
  24. Give different types of sense organ in fishes.
  25. What are electric fishes?
  26. Describe osmoregulation in fresh water fishes.
  27. Describe osmoregulation in Elasmobranchs.
  28. Discuss excretion in fishes.
  29. Write not on placental care in fishes.
  30. What types of evolutionary trend have been observed in fishes?
  31. Describe the evolution of terrestrial vertebrates form fishes.


1. How can you say that “life is impossible without water”.

Ans: Water is a buoyant medium. It resists rapid fluctuations in temperature. Water covers over 70% of the earth’s surface. Life began in water. The living tissues of the organism are made mostly of water. Therefore, life is impossible without water.

2. What is dentine?

Ans: The mouth is filled with root like structures made of dentine. Dentine is found in the vertebrate skeleton.

3. Evolution of fishes occurs whether in marine or fresh water environment.

Ans: It is difficult to know that whether the first vertebrate was marine or fresh water. The ancient deutrostome phyla were all marine. Therefore, the first vertebrates were also marine.

4. Give two characteristics of Agnathans.

Ans: They lack jaws and paired appendages. They have cartilaginous skeleton.

5. What are ostracoderms?

Ans: Ostracoderms are extinct agnathans. They are belonged to several classes. The fossils of predatory water scorpions are found with fossils of ostracoderms.

6. Give two characters of class Myxini.

Ans: Their mouth has four pairs of tentacles. The olfactory sacs open to mouth cavity.

7. What are Gnathostomes?

Ans: The jawed vertebrates are called Gnathostomes.

8. Name the classes of Gnathostomes.

Ans: Class Chondrichthyes, Class Osteichthves, Placoderms and Acanthodians

9. Give two characteristics of Subclass Elasmobranchs.

Ans: Their cartilaginous skeleton may be partially ossified. Placoid scales are present or they have no scales.

10. When and form which animal evolution of shark occurred?

Ans: Sharks arose from early jawed fishes in the Devonian period about 375 million years ago.

11. What is the function of crown of teeth?

Ans: Crowns of teeth are adapted for tearing prey or for crushing the shells of molluscs.

12. Name two species of rays.

Ans: Electric rays and manta rays.

13. Give two characteristics of Sarcopterygii.

Ans: They have paired fins with muscular lobes. The pneumatic sacs function as lungs.

14. Name species of Neoceratodus.



Ans: Neoceratodus, Protopterus and Lepidosiren.

15. What is aestivation?

Ans: Aestivation is a dormant state that helps an animal withstands hot, dry periods.

16. What are lung fishes?

Ans: The air sac in these fish is changed into lungs. Therefore, they are called lung fishes.

17. What is Latimaria?

Ans: Latimaria is a large fish. Its weight is up to 80 kg. It has heavy scales on its body wall. Ancient coelacanths lived in freshwater lakes and rivers.

18. What is homocercal tail?

Ans: In this case, the tail fin has equal upper and lower lobes.

19. Name the modern body fishes.

Ans: Teleosts

20. How do fishes uses less energy for swimming than running from a terrestrial organism?

Ans: The fish have streamlined shape. Its mucoid secretions lubricate its body surface. It reduces friction between the fish and the water. The buoyant properties of water also increase the efficiency of movement fish through the water.

21. What are gill rakers?

Ans: Herring, paddlefishes and whale sharks are filter feeders. They have long gill processes, called gill rakers. These gill rakers trap plankton during swimming with open mouth.

22. What afferent and efferent vessels?

Ans: Afferent vessels carry blood to the gills. These vessels branch into capillaries in gills. Oxygenation takes place and blood is collected by efferent vessels.

23. What is Ram ventilation?

Ans: Some elasmohranchs and open-ocean bony fishes like tuna keep their mouths open during swimming. It maintains water flow in the pharynx. This method is called ram ventilation.

24. Give two characteristics for buoyancy regulation.

Ans: The fishes incorporate low-density compounds into their tissues. Fishes are saturated with buoyant oils. The fishes use fins to provide lift.

25. What is Rete mirabile?

Ans: Rete mirabile is a vascular network.

26. What is lateral line system in fishes?

Ans: Most fishes have lateral-line system. It runs along each side and branching over the head of fishes. The lateral line system consists of sensory pits.

27. What is Electroreception?

Ans: Electroreception is the detection of electrical fields that the fish or another organism generates in the environment.

28. What is osmoregulation?

Ans: The maintenance of water and salt balance in the body is called osmoregulation.

29. What type of glomerulus and tubule system?

Ans: The nephrons of freshwater fishes possess large glomeruli and short tubule systems. Reabsorption of some ions and organic compounds takes place after filtration.

30. What problem is faced by marine fishes in marine environment?

Ans: Marine fishes face the opposite problems. Their environment contains 3.5% ions. But their tissues contain 0.65% ion. Therefore, marine fishes face the problem of water loss and accumulation of excess ions.

31. What are diadromous fishes?

Ans: Diadromous fishes migrate between Freshwater and marine environments.

32. What are Ovoviviparous fishes?

Ans: Some elasmobranchs are ovoviviparous. Their embryos develop in a modified oviduct of the female. Nutrients are supplied from yolk stored in the egg.

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