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Yeshwantrao Chavan Mahavidyalaya , Tuljapur , Dist.-Osmanabad-413 601 (MH), INDIA

Yeshwantrao Chavan Mahavidyalaya , Tuljapur , Dist.-Osmanabad-413 601 (MH), INDIA. Department of Fishery Science. Dr S L Bhalkare Head and Assistant prof. B.Sc. First Year Semester I Paper I Topic: General Chas.Agnatha. Key Features. Jaws are absent. Paired fins are generally absent.

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Yeshwantrao Chavan Mahavidyalaya , Tuljapur , Dist.-Osmanabad-413 601 (MH), INDIA

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  1. YeshwantraoChavanMahavidyalaya, Tuljapur, Dist.-Osmanabad-413 601 (MH), INDIA Department of Fishery Science Dr S L Bhalkare Head and Assistant prof.

  2. B.Sc. First Year Semester I Paper I Topic: General Chas.Agnatha

  3. Key Features • Jaws are absent. • Paired fins are generally absent. • Early species had heavy bony scales and plates in their skin

  4. Key features con’t • In most cases the skeleton is cartilaginous. The embryonic notochord persists in the adult. • Seven or more paired gill pouches are present. • Hagfish sheds slime layer

  5. Key features con’t • A light-sensitive pineal eye is present. • The digestive system lacks a stomach. • External fertilization; both ovaries and testes present in individual but gonads of only one sex functional in hagfishes, no larval stage; separate sexes and a long larval stage in lampreys.

  6. Hagfish • Hagfish can be found in chilly waters • They tend to live on and in muddy sea floors in very dense groups (up to 15,000 in an area). • Because females tend to produce large eggs in small numbers, their population sizes suggest a low death rate.

  7. Hagfish • Diet is made up of marine worms and other invertebrates • They have a ring of short sensitive tentacles around their mouths. • Large slime glands line their sides along the length of their bodies. • Can sneeze to clear slime from nostrils

  8. No jaws. Instead they have two pairs of rasps on top of a tongue. They pull meat into their mouths with the tongue, then tear it off the prey with the rasps.

  9. Hagfish Anatomy

  10. Hagfish have a very low metabolism. Once they eat, they may not have to again for up to seven months. • Although hagfish have a partial skull, they have no back bone, so are not true vertebrates. What skeleton they do have is made of cartilage.

  11. Lamprey Classification • Kingdom Animalia • Phylum Chordata • Subphylum Vertebrata • Class Cephalaspidomorphi • Order Petromyzontiformes • Family Petromyzontidae

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