Phylum Chordata

Types of invertebrate chordates

lack a back bone

1. lancelets - cephalochordata

2. tunicates - urochordata

types of vertebrate chordates

have bony vertebral column

1. fish

2. amphibians

3. reptiles

4. birds

5. mammals

Key features that appear at some stage of chordate development

• a notochord: point of muscle attachment

• a dorsal hollow nerve chord

• pharyngeal slits: associated w respiration

• a pot-anal tail

What is a notochord?

a flexible, rod-shaped structure found in the embryonic state of all chordates and the adult state of some chordates

Where is the notochord located?

• it is located between the digestive tube and the nerve chord

• is not found in the postnatal stage of vertebrates; replaced by vertebral column (spine)

What is the function of a notochord?

provides skeletal support through the length of the body

Characteristics of fish

• vertebral column

• jaws and paired appendages

• internal gills

• single-loop blood circulation - 2 chambered heart

What is the craniata?

a bony, cartilaginous structure surrounding the brain, jaw, and facial bones

What are chondrichthyes?

clade of cartelagenous fish

ex: sharks, skates, rays chimeras

• jawed fishes that possess paired fins and a skeleton made of cartilage

Traits of clade osteichthyes?

• bony skeleton

• use gills to breathe

• swim bladder

• lateral line system - detect vibrations in water

• covered in scales

• operculum

What is a swim bladder?

a gas filled organ that helps to control the buoyancy of the fish

What are the 2 major groups of body fishes?

1. class actinopterygii: ray-finned fishes

2. class sarcopterygii: lobe-finned fishes

Traits of class actinopterygii

• parallel bony rays support and stiffen each fin

• there are no muscles within the fins

Traits of class sarcopterygii

have paired fins - consist of long fleshy muscular lob, supported by central core of bones with fully articulated joints