The Craniates Craniata Subphylum Hyperotretihagfish Subphylum Vertebrataostracoderms lamprey

The Craniates Craniata Subphylum Hyperotretihagfish Subphylum Vertebrataostracoderms lamprey Gnasthostome fishes

Craniata Skull made of cartilage or fibrous tissue n Surrounds brain n Olfactory organs n Eyes n Inner ear n

Subphylum Hyperoptreti n Hagfish Most primitive of all craniates n Brain n Bone Both brain and bone key elements in evolution n

Subphylum Vertebrata n The hyperoartian n lamprey Gnathostomata Cartilaginous fishes n Bony fishes n

Survey of Fishes Subphylum Hyperotreti- Hagfish n Subphylum Vertebratan Ostracoderms n Lampreys n Gnathostome Fishes n

Subphylum Hyperotreti n Class Myxini Hagfishn Heads supported by cartilaginous bars n Brains enclosed in fibrous sheath n Lack vertebrae n Retain notochord as axial support n

Four pairs of sensory tentacles surrounding mouths n Ventrolateral slime glands n

Coldwater marine habitats n Buried in sand mud n Feed on soft bodied invertebrates n And scavenge on dying fish n

Subphylum Vertebrata Vertebrae that serve as a primary axial support n Include Jawless ostacoderms and Hyperoartia (Lamprey) n Most part of a Superclass Gnathostomata n Include jawed fish and tetrapods n

Ostracoderms Extinct agnathans n Bony armor n Bottom dwellers n Extracting annelids and other inverts from sediment n Bony plates around mouth- jaw like structure n

Hyperoartia n Class Cephalaspidomorphi Lamprey (agnathas) n Marine and freshwater n Prey on other fish n Larvae filter feeders n Mouth is suckerlike n Epidermal teeth, rasping tongue n Glands secrete anticoagulant and feed on blood n External fertilization n

Gnathostomata n n Jaws evolved from anterior gill support arches that had acquired a new role, being modified to pump water over the gills by opening and closing the mouth more effectively. The mouth could then grow bigger and wider, making it possible to capture small prey. This close and open mechanism would with time become stronger and tougher, being transformed into real jaws. Modified dermal bones on the surface of the skin would migrate into the mouth and become primtive teeth.

Paired appendages Increased activity n Increased stability n Lateral steering n Pectoral fins- usually just behind the head n Pelvic fins- ventral and more posteriorly n n Modern bony fishes pelvic fins usually behind the pectoral fins

n Ability to feed efficiently Produced more offspring and exploit new habitat Fostered adaptive radiation n Cartilaginous fishes n n Class Chondrichthyes Bony fish n Class Osteichthyes

Class Chondrichthyes Sharks n Skates n Rays n Ratfishes n

Most carnivores or scavengers n Marine n Biting mouthparts n Paired appendages n Placoid scales n Cartilagious endoskeleton n

Class Osteichthyes Bone in their skeleton n and/or scales, n bony operculum covering gill openings and n lungs or swim bladder. n