Contents Jenna Hellack Fall 2000 Lesser Deuterostome Phyla and Phylum Chordata(through agnathans)

Contents Jenna Hellack Fall 2000 Contents Chaetognatha ChaetognathaPhylum: ChaetognathaChaetognatha Hemichordata HemichordataPhylum: HemichordataHemichordata Chordata ChordataPhylum: ChordataChordata Urochordata Urochordata  Subphylum: UrochordataUrochordata Cephalochordata Cephalochordata  Subphylum: CephalochordataCephalochordata  Subphylum: Vertebrata (Craniata) Vertebrata Superclass AgnathaSuperclass Agnatha  Class: Myxini Myxini  Class: Cephalaspidomorphi Cephalaspidomorphi

Contents Jenna Hellack Fall 2000 Phylum Chaetognatha Arrow worms  Stratified skin along sides of body.

Contents Jenna Hellack Fall 2000 Phylum Hemichordata Acorn worm  Proboscis, collar and trunk  Like Chordata Gill slits and a hollow, dorsal nerve chord Have stomochord rather than a notochord  Like Echinodermata Tornaria larva resembles bipinnaria larva of echinoderms. Coelomic pouches Nerve plexus

Contents Jenna Hellack Fall 2000 Phylum Chordata Notochord Dorsal tubular nerve cord Pharyngeal gill slits (pouches) Post anal tail Ventral heart Urochordata Cephalochordata Vertebrata

Contents Jenna Hellack Fall 2000 Subphylum Urochordata Tunicates (sea squirts)  Larva has all chordate characteristics  Adult sessile, encased in tunic  Ventral heart with a large vessel on each side. Heart pumps blood through one vessel—, stops, then pumps blood through other vessel.  Endostyle present Chordata

Contents Jenna Hellack Fall 2000 Subphylum Cephalochordata Branchiostoma -the lancelets or Amphioxus  Retain all the chordate characteristics throughout life.  Shows the basic diagnostic chordate characteristics very clearly.  Also possesses several features that suggest the vertebrate plan  Endostyle present Chordata

Contents Jenna Hellack Fall 2000 Subphylum Vertebrata Chordate characteristics present at some stage of life cycle. Integumentary - with stratified epidermis and an inner dermis present. Skeletal -Notochord at least partly replaced by vertebrae. A cranium present. Nervous- 10 to 12 pairs of cranial nerves Excretory - vertebrate kidney (at least mesonephric in adults) Chordata Myxini Cephalaspidomorphi

Contents Jenna Hellack Fall 2000 Class: Myxini Hagfishes  Naked skin containing slime glands  No paired appendages  No jaws  Notochord and other chordate characters persistent  Systems Systems  Representative pictures Representative pictures Representative pictures Vertebrata

Contents Jenna Hellack Fall 2000 Myxini systems  Systems CirculatoryCirculatory - Two chambered heart with aortic arches in gill region have accessory hearts in caudal region. ExcretoryExcretory - pronephric with independent mesonephric kidney posteriorly, isosmotic to sea water. RespiratoryRespiratory - 5 to 16 pairs of gills (one pair or more gill openings) DigestiveDigestive -complete, with no jaws or stomach present NervousNervous- they have 10 pair of cranial nerves, no cerebellum. Dorsal and ventral nerve roots united. IntegumentaryIntegumentary- No scales, skin with slime glands SkeletalSkeletal - cartilaginous with persistent notochord. ReproductiveReproductive - both male and female gonads found in some animals, but one one gonad is functional. No larval stage. Life cycle largely unknown EndocrineEndocrine - pineal gland present, there are islets of pancreas cells around the bile duct MuscleMuscle - myomeres alternate Myxini

Contents Jenna Hellack Fall 2000 Myxini representatives Ventral viewLateral view Myxini

Contents Jenna Hellack Fall 2000 Class: Cephalaspidomorphi Lampreys  Slender eel-like body without scales  No paired appendages  Cartilaginous skeleton, notochord persistent  No jaws—Sucker-like oral disc, has teeth and tongue.  Ammocoete larvae  Systems Systems  Representative pictures Representative pictures Representative pictures Vertebrata

Contents Jenna Hellack Fall 2000 Lamprey Systems IntegumentaryIntegumentary- No scales, stratified skin SkeletalSkeletal- Cartilaginous, notochord persistent, no paired appendages. CirculatoryCirculatory- Two chambered heart, aortic arches in gill region. RespiratoryRespiratory - seven pairs of gills each with and external opening. ExcretoryExcretory- Mesonephric kidney, hypotonic sea water, have to osmotically and ionic regulate. NervousNervous- 10 pairs of cranial nerves, dorsal and ventral nerve roots separated, small cerebellum present. EndocrineEndocrine- pineal structure, pituitary body present, endostyle present in larvae is thyroid gland present in adult. MuscleMuscle - short segmental muscles as in other fishes Digestive-Digestive- complete, no stomach, liver does not have a bile duct, pancreas cluster of cells near liver. ReproductiveReproductive - dioecious, larvae= Ammocoete, look much like amphioxus, are freshwater filter feeders. Cephalaspidomorphi

Contents Jenna Hellack Fall 2000 Cephalaspidomorphi examples Ammocoete larvae Juvenal lampreys Adult lamprey mouth with tongue and teeth Adult lamprey - lateral view Cephalaspidomorphi