Early Chordate introduction Notes

The most recently evolved animal The most recently evolved animal phylum is called Chordata.phylum is called Chordata.

Chordates are characterized by …Chordates are characterized by …

Chordates are characterized by …Chordates are characterized by …

1.1. A dorsal, hollow nerve chord.A dorsal, hollow nerve chord.

Chordates are characterized by …Chordates are characterized by …

1.1. A dorsal, hollow nerve chord.A dorsal, hollow nerve chord.2.2. A dorsal notochord to support the A dorsal notochord to support the

body.body.

Chordates are characterized by …Chordates are characterized by …

1.1. A dorsal, hollow nerve chord.A dorsal, hollow nerve chord.2.2. A dorsal notochord to support the A dorsal notochord to support the

body.body.3.3. A post anal tail at some stage of A post anal tail at some stage of

development.development.

Chordates are characterized by …Chordates are characterized by …

1.1. A dorsal, hollow nerve chord.A dorsal, hollow nerve chord.2.2. A dorsal notochord to support the A dorsal notochord to support the

body.body.3.3. A post anal tail at some stage of A post anal tail at some stage of

development.development.4.4. Seven pharyngeal clefts (gills) at Seven pharyngeal clefts (gills) at

some stage of development.some stage of development.

About 0.5% of humans have a vestigial remnant of the anterior –most gill slit. It appears as a tiny opening at the front edge of the ear on one or both sides of the head.

Phylum Chordata is divided into three subphyla, two of which are invertebrates.

Subphylum Urochordata

Phylum Chordata is divided into three subphyla, two of which are invertebrates.

Subphylum Urochordata

Phylum Chordata is divided into three subphyla, two of which are invertebrates.

Subphylum Urochordata

Subphylum Cephalochordata

Tunicate larvae are somewhat fish-like.Tunicate larvae are somewhat fish-like.

The third subyphylum, called Vertebrata, is The third subyphylum, called Vertebrata, is divided into 10 classes, 2 of which are extinct.divided into 10 classes, 2 of which are extinct.

The third subyphylum, called Vertebrata, is The third subyphylum, called Vertebrata, is divided into 10 classes, 2 of which are extinct.divided into 10 classes, 2 of which are extinct.

• Myxini – hagfishesMyxini – hagfishes

The third subyphylum, called Vertebrata, is The third subyphylum, called Vertebrata, is divided into 10 classes, 2 of which are extinct.divided into 10 classes, 2 of which are extinct.

• Myxini – hagfishesMyxini – hagfishes• Cephalaspidomorphi - Cephalaspidomorphi -

lampreyslampreys

The third subyphylum, called Vertebrata, is The third subyphylum, called Vertebrata, is divided into 10 classes, 2 of which are extinct.divided into 10 classes, 2 of which are extinct.

• Myxini – hagfishesMyxini – hagfishes• Cephalaspidomorphi - Cephalaspidomorphi -

lampreyslampreys• OstracodermiOstracodermi

The third subyphylum, called Vertebrata, is The third subyphylum, called Vertebrata, is divided into 10 classes, 2 of which are extinct.divided into 10 classes, 2 of which are extinct.

• Myxini – hagfishesMyxini – hagfishes• Cephalaspidomorphi - Cephalaspidomorphi -

lampreyslampreys• OstracodermiOstracodermi• PlacodermiPlacodermi

The third subyphylum, called Vertebrata, is The third subyphylum, called Vertebrata, is divided into 10 classes, 2 of which are extinct.divided into 10 classes, 2 of which are extinct.

• Myxini – hagfishesMyxini – hagfishes• Cephalaspidomorphi - Cephalaspidomorphi -

lampreyslampreys• OstracodermiOstracodermi• PlacodermiPlacodermi• Elasmobranchomorphi – Elasmobranchomorphi –

cartilaginous fishescartilaginous fishes

The third subyphylum, called Vertebrata, is The third subyphylum, called Vertebrata, is divided into 10 classes, 2 of which are extinct.divided into 10 classes, 2 of which are extinct.

• Myxini – hagfishesMyxini – hagfishes• Cephalaspidomorphi - Cephalaspidomorphi -

lampreyslampreys• OstracodermiOstracodermi• PlacodermiPlacodermi• Elasmobranchomorphi – Elasmobranchomorphi –

cartilaginous fishescartilaginous fishes

• Osteichthyes – bony Osteichthyes – bony

fishes fishes

The third subyphylum, called Vertebrata, is The third subyphylum, called Vertebrata, is divided into 10 classes, 2 of which are extinct.divided into 10 classes, 2 of which are extinct.

• Myxini – hagfishesMyxini – hagfishes• Cephalaspidomorphi - Cephalaspidomorphi -

lampreyslampreys• OstracodermiOstracodermi• PlacodermiPlacodermi• Elasmobranchomorphi – Elasmobranchomorphi –

cartilaginous fishescartilaginous fishes

• Osteichthyes – bony Osteichthyes – bony

fishes fishes• AmphibiaAmphibia

The third subyphylum, called Vertebrata, is The third subyphylum, called Vertebrata, is divided into 10 classes, 2 of which are extinct.divided into 10 classes, 2 of which are extinct.

• Myxini – hagfishesMyxini – hagfishes• Cephalaspidomorphi - Cephalaspidomorphi -

lampreyslampreys• OstracodermiOstracodermi• PlacodermiPlacodermi• Elasmobranchomorphi – Elasmobranchomorphi –

cartilaginous fishescartilaginous fishes

• Osteichthyes – bony Osteichthyes – bony

fishes fishes• AmphibiaAmphibia• ReptiliaReptilia

The third subyphylum, called Vertebrata, is The third subyphylum, called Vertebrata, is divided into 10 classes, 2 of which are extinct.divided into 10 classes, 2 of which are extinct.

• Myxini – hagfishesMyxini – hagfishes• Cephalaspidomorphi - Cephalaspidomorphi -

lampreyslampreys• OstracodermiOstracodermi• PlacodermiPlacodermi• Elasmobranchomorphi – Elasmobranchomorphi –

cartilaginous fishescartilaginous fishes

• Osteichthyes – bony Osteichthyes – bony

fishes fishes• AmphibiaAmphibia• ReptiliaReptilia• AvesAves

The third subyphylum, called Vertebrata, is The third subyphylum, called Vertebrata, is divided into 10 classes, 2 of which are extinct.divided into 10 classes, 2 of which are extinct.

• Myxini – hagfishesMyxini – hagfishes• Cephalaspidomorphi - Cephalaspidomorphi -

lampreyslampreys• OstracodermiOstracodermi• PlacodermiPlacodermi• Elasmobranchomorphi – Elasmobranchomorphi –

cartilaginous fishescartilaginous fishes

• Osteichthyes – bony Osteichthyes – bony

fishes fishes• AmphibiaAmphibia• ReptiliaReptilia• Aves - birdsAves - birds

The third subyphylum, called Vertebrata, is The third subyphylum, called Vertebrata, is divided into 10 classes, 2 of which are extinct.divided into 10 classes, 2 of which are extinct.

• Myxini – hagfishesMyxini – hagfishes• Cephalaspidomorphi - Cephalaspidomorphi -

lampreyslampreys• OstracodermiOstracodermi• PlacodermiPlacodermi• Elasmobranchomorphi – Elasmobranchomorphi –

cartilaginous fishescartilaginous fishes

• Osteichthyes – bony Osteichthyes – bony

fishes fishes• AmphibiaAmphibia• ReptiliaReptilia• Aves - birdsAves - birds• MammaliaMammalia

The third subyphylum, called Vertebrata, is The third subyphylum, called Vertebrata, is divided into 10 classes, 2 of which are extinct.divided into 10 classes, 2 of which are extinct.

• Myxini – hagfishesMyxini – hagfishes• Cephalaspidomorphi - Cephalaspidomorphi -

lampreyslampreys• OstracodermiOstracodermi

The third subyphylum, called Vertebrata, is The third subyphylum, called Vertebrata, is divided into 10 classes, 2 of which are extinct.divided into 10 classes, 2 of which are extinct.

• Myxini – hagfishesMyxini – hagfishes• Cephalaspidomorphi - Cephalaspidomorphi -

lampreyslampreys• OstracodermiOstracodermi

These three vertebrate These three vertebrate classes lack jaws. They classes lack jaws. They cannot close their mouth.cannot close their mouth.

The third subyphylum, called Vertebrata, is The third subyphylum, called Vertebrata, is divided into 10 classes, 2 of which are extinct.divided into 10 classes, 2 of which are extinct.

• Myxini – hagfishesMyxini – hagfishes• Cephalaspidomorphi - Cephalaspidomorphi -

lampreyslampreys• OstracodermiOstracodermi

These three vertebrate These three vertebrate classes lack jaws. They classes lack jaws. They cannot close their mouth.cannot close their mouth.

Such animals are called Such animals are called AgnathansAgnathans..

The third subyphylum, called Vertebrata, is The third subyphylum, called Vertebrata, is divided into 10 classes, 2 of which are extinct.divided into 10 classes, 2 of which are extinct.

• Myxini – hagfishesMyxini – hagfishes• Cephalaspidomorphi - Cephalaspidomorphi -

lampreyslampreys• OstracodermiOstracodermi

These three vertebrate These three vertebrate classes lack jaws. They classes lack jaws. They cannot close their mouth.cannot close their mouth.

Such animals are called Such animals are called AgnathansAgnathans..

A – withoutA – without

The third subyphylum, called Vertebrata, is The third subyphylum, called Vertebrata, is divided into 10 classes, 2 of which are extinct.divided into 10 classes, 2 of which are extinct.

• Myxini – hagfishesMyxini – hagfishes• Cephalaspidomorphi - Cephalaspidomorphi -

lampreyslampreys• OstracodermiOstracodermi

These three vertebrate These three vertebrate classes lack jaws. They classes lack jaws. They cannot close their mouth.cannot close their mouth.

Such animals are called Such animals are called AgnathansAgnathans..

A – withoutA – withoutgnath - jawgnath - jaw

The remaining seven classes (one of which is extinct) have jaws.

The remaining seven classes (one of which is extinct) have jaws. Vertebrates with jaws are called gnathostomes.

The remaining seven classes (one of which is extinct) have jaws. Vertebrates with jaws are called gnathostomes.

Gnath – jaws

The remaining seven classes (one of which is extinct) have jaws. Vertebrates with jaws are called gnathostomes.

Gnath – jaws

Stome – hole (referring to the mouth)

The remaining seven classes (one of which is extinct) have jaws. Vertebrates with jaws are called gnathostomes.

Gnath – jaws

Stome – hole (referring to the mouth)

Literally a mouth with jaws.

Gill slit

Gill cleft

If you think about this, it means that If you think about this, it means that you are closely related to tunicates you are closely related to tunicates and amphioxus as a spider is to an and amphioxus as a spider is to an insect.insect.