page 5 in lab manual anterior posterior

Phylum Chordata Subphylum Urochordata (Tunicata) Subphylum Cephalochordata “Craniata” group Subphylum Vertebrata Superclass Agnatha Superclass Gnathostomata Class Placodermi Class Chondrichthyes Class Acanthodii Class Osteichthyes Class Amphibia Class Reptilia Class Mammalia Class Aves

Scavenge dead, dying fish and invertebrates. Have funnel-like mouths - tongue rasps off food. Hagfish

 Where are hagfish classified?

Asian aphrodisiac

Phylum Chordata Subphylum Urochordata (Tunicata) Subphylum Cephalochordata “Craniata” group Subphylum Vertebrata Superclass Agnatha Superclass Gnathostomata Class Placodermi Class Chondrichthyes Class Acanthodii Class Osteichthyes Class Amphibia Class Reptilia Class Mammalia Class Aves

 Metameric skeletal elements flanking the nerve cord.  Neural arch was first element to evolve Vertebrates

Hagfish Lamprey Shark

June, 2011 Hagfish vertebral elements??

“Ostracoderms” – million years ago - early jawless fish  head shields w/mineralized bone  small bottom-dwelling

Calcium phosphate mineralized tissue makes head shield and is related to teeth and scales  enamel and dentine  developmental interaction of epidermis and dermis

 Usually no paired fins  Notochord mostly remains  Single nostril Ancestral jawless fish

Main groups of modern jawless fish:  Hagfish (Myxiniformes)  Lamprey (Petromyzontiformes) Similarities in these two groups are probably due to evolutionary convergence (homoplasy)

Lamprey

Water flows in mouth, through respiratory tube and out gills Lamprey respiration

Respiratory tube internally connects gill pores  Specialized flap - velum can close off anterior end of respiratory tube !!

Respiratory tube internally connects gill pores  Specialized flap - velum can close off anterior end of respiratory tube !!

Branchial muscles squeeze water in and out of respiratory tube and over gills  “Tidal ventilation” !!

Ammocetes - larval form of lamprey up to 7 years Uses muscular movements to make feeding current.

Crassus - Roman general

Phylum Chordata Subphylum Urochordata (Tunicata) Subphylum Cephalochordata “Craniata” group Subphylum Vertebrata Superclass Agnatha Superclass Gnathostomata Class Placodermi Class Chondrichthyes Class Acanthodii Class Osteichthyes Class Amphibia Class Reptilia Class Mammalia Class Aves

- Superclass: Gnathostomata “jaw-mouthed vertebrates” ~430 million years ago

Two new characteristics:  A jaw - Allows consumption of larger, more diverse prey.

Mandibular arch Hyoid arch Gill arches

Two new characteristics:  Jaw - Allows consumption of larger, more diverse prey.  Paired fins - at least two sets of paired fins: pectoral and pelvic. Gives stability and lift, prevents roll. pitch yaw roll

Big evolutionary radiation after advent of first jawed fish...  Acanthodians  Placoderms  Chondrichthyes  Sarcopterygii  Actinopterygii

Phylum Chordata  Subphylum Urochordata (Tunicata)  Subphylum Cephalochordata Craniata group  Subphylum Vertebrata  Superclass Agnatha  Superclass Gnathostomata Class Placodermi Class Chondrichthyes Class Acanthodii Class Osteichthyes Class Amphibia Class Reptilia Class Mammalia Class Aves

Acanthodians - Body armor like ostracoderms, fins w/spines  Skeleton had some bone (p.63)

Placoderms - “plate-skinned” fish  Bony plates are in smaller pieces compared to ostracoderms  Mostly fed on bottom, some mid-level predators (p.59) placoderm skull 1 fossil shows live birth

Placoderm - up to 20 ft, 1 ton First vertebrate “giants” Bite could exert 22,000lbs of force per sq inch Dunkleosteus