- Agnatha are a class of primitive jawless fish that include lampreys and hagfish. - Lampreys have a worldwide distribution and migrate to freshwater to spawn. They have two dorsal fins, no scales, and attach to other fish using a toothed, sucker-like mouth to feed as parasites. - Hagfish also live in marine environments worldwide. They have a soft, eel-like body without scales or jaws, and feed on carrion using tentacles around their mouth.

2. AGNATHA
DR.DILLA JOSE

4. Class
Cyclostomata(Marsipobranchii)
Order
Petromyzontia Myxinoidea
Eg. Petromyzon Eg. Myxine
(Lamprey) (Hagfish)

5.  3 species in Northern hemisphere
Petromyzon marinus (Sea lamprey)
P. fluviatilis (River lamprey)
P. planeri (Brook lamprey)
World – wide distribution
2 dorsal fins, caudal fins conti…
Skin is soft, slimy and is devoid of scales.
A pair of eyes, internal pineal organ
Single nasal aperture
Sexes are separate
Migrates to fresh water
External fertilization
Ammocoetes larva

6. 7 gill apertures Buccal funnel or sucker
Horny teeth, rasping tongue

7. Ectoparasitic
Salivary glands…
 secretion (Lamphredin) prevents the blood from clotting.

8. The adult Lamprey migrates only once
to the river for spawning and dies
after this process.
Nest bulding:

9. Larva
• Bounding the mouth there is a oral hood- like
upper lip and a distinct lower lip.
• Buccal funnel absent in the larva
• No teeth.
• Paired eyes not functional.
• Gill- slits, varying in number.
• Feeding on small organism

10. Eg. Myxine

11.  Members belonging to the order
Myxiniformes are commonly known
as hagfishes.
Myxine has a wide distribution along
sea coasts of both Atlantic and pacific
Oceans, Japan, etc.
Body is eel-like, measuring about 2
feet (50-60 cm) in length and
differentiated into head, trunk and
tail.

12. The surface of the body is soft and smooth
without scales.
Lateral to the mouth are four pairs of short
tentacles supported by skeletal rods.
 Nostril is single, lies very close to the mouth
and opens terminally.
Single pineal eye is visible on the top of the
head.
 Paired eyes are vestigial or degenerated due
to bottom dwelling habit.