User:Harshita/E-Museum/Cyclostomata

= Petromyzon =

Common name: Lamprey or Lamper eel

Geographical distribution: World-wide distribution,present in both salt and fresh water of North America,West Africa,Japan, Europe, Chili,Australia,New Zealand and Tasmania

Food: carnivorous.Quasi-parasite regarded as their predator

Comments:-

1. Body: eel-like and differentiated into head ,trunk, and tail

2. Body length : 1m

3. Smooth and slimy surface of body generally pigmented

4. Head : great forward development of the upper lip region forming the buccal funnel

5. Mouth : circular and armed with numerous horny teeth

6. large and functional paired eyes .2 small median eyes -the pineal and parietal eyes

7. Dorsal and single nostril

8. 7 pairs of external gill aperture and well-developed branchial - basket

9. Cartilaginous rays support 2dorsal fins and 1 caudal fin

10. Absence of jaws and paired fins

11. In adults sexes are separate and there is single large gonad

12. External fertilization

13. On fishes it lead an ectoparasite life

= Myxine =

Common name: Hagfish

Geographical distribution:wide distribution along sea coasts of both Atlantic and Pacific oceans, occuring in the waters of Northern Europe , North Atlantic,America, Chili and Japan

Food: Nocturnal feeders

Habitat: Buried in sea bottom. During day time they live buried in sea bottom at depths of over 600 m

Comments:-

1. Body: eel-like and differentiated into head ,trunk, and tail

2. Body length : 60 cm

3. Body surface is soft and smooth without scales

4. Terminal mouth and surrounded by soft lips

5. Absence of buccal funnel and jaws. Branchial basket is also reduce

6. Lateral to mouth present 4 pairs of short tentacles supported by skeletal rods

7. Single nostril ,lies very close to the mouth and open terminally

8. On the top of the head single pineal eye is visible

9. Vestigeal paired eyes due to bottom dwelling habit

10. 6 pairs of gills present which do not open separately but open via a single external gill opening

11. Single median fin runs from the middle of ventral surface extending around the tail

12. Presence of large mucous gland open by mucous pores

13. Hermaphrodite having single ovotestis, anterior part is ovary and posterior is testis

14. Animals are quasi- parasitic because they sometimes found within the body of the prey.