Vertebrate Zoology Agnatha Hagfish Lamprey Key Features o

Vertebrate Zoology Agnatha Hagfish & Lamprey

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

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

Key features con’t Ø A light-sensitive pineal eye is present. Ø The digestive system lacks a stomach. Ø 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.

Hagfish Classification • • Kingdom Animalia Phylum Chordata Class Pteraspidomorphi Order Myxiniformes Family Myxinidae Genus Myxine Species glutinosa

Slime Glands

Hagfish ü ü ü 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.

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

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.

Hagfish Anatomy

/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.

Lamprey Classification /Kingdom Animalia /Phylum Chordata /Subphylum Vertebrata /Class Cephalaspidomorphi /Order Petromyzontiformes /Family Petromyzontidae