Chordates and Vertebrates

The Agnatha – Jawless Fish

HomeworkRead p 146- 147

1. 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

Ven

tral

Post

erio

r

Dors

al

Ante

rior

8%0%

92%

0%

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 ChordatesFilter 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“ BUTCephalochordates 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

Ben

thic

Infa

una

Ses

sile

Dem

ersa

l

23%

8%

62%

8%

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

3 5 4 2

15%

8%

23%

54%

1. 3

2. 5

3. 4

4. 2

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