Bio 112- Vertebrates

Phylum Chordata

Chordates are bilateral and are deuterostomes

Chordate common features

1. Notochord

2. Dorsal, hollow nerve chord

3. Pharyngeal gill slits

4. Post-anal tail

Notochord

A flexible rod that supports a chordate's back just below the nerve cord.

Dorsal hollow nerve chord

Nerve cord found in all chordates that forms the spinal cord and brain

-Above the notochord

Pharyngeal slits/clefts

Develop from the pharynx behind the mouth into slits that:

- water flow into mouth without it entering digestive tract

- help with suspension feeding & aquatic respiration

-Exception for tetrapods

Muscular post-anal tail

tail that extends posteriorly to anus

-help some species with locomotion/propulsion

Vertebrates

chordates with backbones

Vertebrate Characteristics

1. Spinal column develops around notochord

2. Hox genes

3. Complete nervous system

4. 2 chambered heart

Hox genes

series of genes that controls the differentiation of cells and tissues in an embryo

Class Myxini

Hagfish

1. Cartilage skull

2. Jawless

3. Teeth made from keratin

4. Bottom dwellers that produce slime

Class Petromyzontida

Lampreys

1. Most are parasitic

2. Jawless

3. Cartilage skeleton

Class Chondrichthyans

Sharks and Rays

- Cartilage skeleton

- No ears

Class Actinopterygii

ray-finned fish (commonly known fish)

-Bony rays support fins

Class Sarcopterygii

lobe-finned fish

-Rod shaped bone surround muscle in fins

-Fins used to walk on land

Actinista

Ancient lineage of aquatic lobe-fins still surviving in Indian Ocean

Dipnoi

lungfish

Tetrapods

vertebrate animals having four feet, legs or leglike appendages

-Pharyngeal clefts give rise to INNER EAR bones and glands

Class Amphibia

Salamanders, Frogs, & Caecilians

-larval aquatic

-Adult terrestrial

Order Urodela

salamanders and newts

-Undergo Pedomorphosis

Pedomorphosis

adult species retains traits that were previously only seen in juveniles

Oder Anura

frogs and toads

-Skin glands secrete distasteful or toxic compounds

Oder Apoda

Caecilians

-Legless

-nearly blind

-burrowers

Class Reptilia

1. Scales made of keratin

2. Lay shelled eggs on land and internal fertilization

3. Most are ectothermic except birds

Anapsid skull

Skull with no holes/temporal openings

-Turtles

-Amphibians

Euryapsid skull

Skull with one hole

-Extinct marine reptiles

Synapsid skull

Skull with 1 bottom hole

-mammals

Diapsid skull

Skull has pair of temporal openings

-Reptiles

-Birds

Lepidosaurs

lizards, snakes, tuataras

Archosaurs

Crocodiles, alligators and dinosaurs, including birds.

Gnathosomes

vertebrates with jaws

Gnathosome characteristics

1. Additional duplication of Hox genes

2. Enlarged forebrain

3. Start of paired appendages

Tetrapods

gnathostomes with limbs

Amniotes

tetrapods with a terrestrially adapted egg, completed the transition to land

What are the 4 membranes of an amniotic egg?

1. Amnion

2. Allantois

3. Yolk Sac

4. Chorion

Amnion

Fluid-filled membrane that protects the embryo

Allantois

Membrane used for gas exchange and waste removal

Yolk Sac

Nourishes embryo

Chorion

Encloses embryo and all internal membranes

Shell

Prevents desiccation and allows gas exchange

Mammals

amniotes that have hair and produce milk

- 4 chambered heart

Mammal characteristics

-mammary glands

-Muscular diaphragm

-Large brain

-Differentiated teeth

-Most do live-birth

Montremes

mammals that lay eggs

Marsupials

pouched mammals

-Give birth to underdeveloped juveniles

Eutherians

much more complex placental mammals

-Entire development in uterus

Cephalochordata

lancelets. "Head cords"

-Are the most basal of chordates

-Larvae has all 4 chordate characteristics

Urochordata

Chordate traits in larvae but are lost in adults

-Sessile filter feeders

-Goes through metamorphosis

Weight-reducing adaptations of Birds

1. No bladder

2. One have 1 ovary

3. Lack teeth

4. Bone wall reduced in thickness

Reduced and fused bones

Ratites

large, flightless birds

-No a keel on sternum

Carinates

Flying birds

-They have a keeled sternum for attachments of their pectoral flight muscles