Chordates and Vertebrates The Agnatha – Jawless Fish

Homework Read p How long ago did the first vertebrate fish appear in the oceans? 2. What are four basic characteristics of vertebrates? 3. What are the most primitive type of fish living today? Give an example. 4. How do hagfish feed? 5. What Kingdom and class are bony fish grouped in?

Phylum Chordata 4 Distinguishing characteristics –Hollow, dorsal nerve cord –Pharyngeal gill slits –Stiffening notochord –Post anal tail –BODY ADVANCES –Dorsal Nerve Cord –Backbone or Notochord

Chordate Characteristics

The nerve cord is found on the ________ side of the organism 1.Ventral 2.Posterior 3.Dorsal 4.Anterior

3 Subphyla of Chordates Urochordates – tunicates Cephalochordates – lancelets Vertebrates – fish, amphibians, reptiles, birds, mammals

Urochordates- Tunicates AKA “Sea Squirts” These are the ONLY sessile Chordates Filter feeders which pump and filter water to feed tunicates have a larva that is free-swimming and exhibits all chordate characteristics : a notochord, a dorsal nerve cord, pharyngeal slits, post-anal tail.

Lancelet Laterally compressed filter feeders. Cephalochordates They Possess -Dorsal Nerve cord -Notocord - pharyngeal slits or "gill slits“ BUT Cephalochordates lack features found in most or all true vertebrates: the brain is very small and poorly developed, sense organs are also poorly developed, and there are no true vertebrae

Subphylum Vertebrata Members have all the major characteristics of the phylum plus… have a vertebral column (backbone or spine) –made up of vertebra –protects nerve cord (spinal cord)

Sea Squirts are 1.Benthic 2.Infauna 3.Sessile 4.Demersal

5 classes of Vertebrates: Birds Fish Reptiles Amphibians Mammals

Vertebrates are built for an active lifestyle Bilateral symmetry Endoskeleton – axial and appendicular Extreme cephalization Complex organ systems

Organ systems are more complex because vertebrates are bigger, more active Respiratory – gills or lungs Circulatory – closed; 2,3 or 4 chambered heart (fish, reptiles, mammals respectively) Digestive – accessory organs for digestion of more varied diets

There are _____ classes of Vertebrates

2 big vertebrate groups Superclass Gnathostomata I –3 classes of fish Superclass Gnathostomata II –All the tetrapods Amphibians Reptiles Birds Mammals

3 fish classes Agnatha – jawless fishes Chondrichthyes – cartilaginous fishes Osteichthyes – bony fishes

Protochordate Overview