Chapter 34Chapter 34

VertebratesVertebrates

VertebratesVertebrates

These are a subphylum of the phylum Chordata.

They are deuterostomes

These are a subphylum of the phylum Chordata.

They are deuterostomes

ChordatesChordates

Bilaterally symmetrical.They are deuterostomes.Have a notochord.

Bilaterally symmetrical.They are deuterostomes.Have a notochord.

Derived Characters of Chordates

Derived Characters of Chordates

4 key characters of chordates:1. A notochord2. A dorsal, hollow nerve cord3. Pharyngeal slits or clefts4. A muscular, post-anal tail

4 key characters of chordates:1. A notochord2. A dorsal, hollow nerve cord3. Pharyngeal slits or clefts4. A muscular, post-anal tail

1. Notochord1. Notochord

A longitudinal, flexible rod between the digestive tube and the nerve cord.

It is fluid filled and provides support for the animal.

A longitudinal, flexible rod between the digestive tube and the nerve cord.

It is fluid filled and provides support for the animal.

1. Notochord1. Notochord

Larvae and adults that retain it: The muscles can

work against it. In animals that

develop a skeleton, the remnants of the notochord are disks.

Larvae and adults that retain it: The muscles can

work against it. In animals that

develop a skeleton, the remnants of the notochord are disks.

2. Dorsal Hollow Nerve Cord

2. Dorsal Hollow Nerve Cord

Develops from a plate of ectoderm.

It rolls into a tube dorsal to the notochord.

Dorsal hollow nerve cords are unique to chordates.

The nerve cord develops into a CNS.

Develops from a plate of ectoderm.

It rolls into a tube dorsal to the notochord.

Dorsal hollow nerve cords are unique to chordates.

The nerve cord develops into a CNS.

3. Pharyngeal Slits or Clefts

3. Pharyngeal Slits or Clefts

The region just posterior to the mouth is the pharynx.

All chordates have a series of pouches separated by grooves that allow water to pass in and out without having to go through the entire digestive tube.

The region just posterior to the mouth is the pharynx.

All chordates have a series of pouches separated by grooves that allow water to pass in and out without having to go through the entire digestive tube.

3. Pharyngeal Slits or Clefts

3. Pharyngeal Slits or Clefts

Invertebrate Chordates:Suspension feeding devices

Non-terrestrialVertebrate Chordates:

Slits and support structures become gills for gas exchange

Terrestrial (tetrapods)Vertebrate Chordates:

Clefts don't become slitsThey develop into important parts of the inner ear, head and neck

Functions:

Invertebrate Chordates:Suspension feeding devices

Non-terrestrialVertebrate Chordates:

Slits and support structures become gills for gas exchange

Terrestrial (tetrapods)Vertebrate Chordates:

Clefts don't become slitsThey develop into important parts of the inner ear, head and neck

Functions:

4. Muscular, Post-Anal Tail4. Muscular, Post-Anal Tail

Many species of chordates lose their tail during embryonic development.

For aquatic animals that retain it, it provides a propelling force for the animal.

Many species of chordates lose their tail during embryonic development.

For aquatic animals that retain it, it provides a propelling force for the animal.

CraniatesCraniates

Craniates are cordates with a head.

They have two clusters of Hox genes.

They have a neural crest.

Craniates are cordates with a head.

They have two clusters of Hox genes.

They have a neural crest.

Neural CrestNeural Crest

These are the cells that appear as the neural tube closes.

These cells get dispersed throughout the body.

They give rise to many structures:Teeth, bones and cartilage of the

skull, the dermis of the face, neurons, sensory organs

These are the cells that appear as the neural tube closes.

These cells get dispersed throughout the body.

They give rise to many structures:Teeth, bones and cartilage of the

skull, the dermis of the face, neurons, sensory organs

CraniatesCraniates

In aquatic craniates, the pharyngeal clefts evolved into gill slits.

In terrestrial craniates, the slits develop into important parts of the inner ear and neck.

In aquatic craniates, the pharyngeal clefts evolved into gill slits.

In terrestrial craniates, the slits develop into important parts of the inner ear and neck.

VertebratesVertebrates

Dlx gene duplication gave rise to increased nervous system complexity, more extensive skull and a backbone with vertebrae.

The vertebrae enclosed the spinal cord.

Dorsal, ventral, and anal fins stiffened with fin rays enhanced swimming.

Dlx gene duplication gave rise to increased nervous system complexity, more extensive skull and a backbone with vertebrae.

The vertebrae enclosed the spinal cord.

Dorsal, ventral, and anal fins stiffened with fin rays enhanced swimming.

GnathostomesGnathostomes

Vertebrates with jaws.Vertebrates with jaws.

Derived CharactersDerived Characters

JawsDuplication of Hox genes:Gave rise to larger brains,

enhancing smell and vision.Aquatic gnathostomes have a

lateral line.

JawsDuplication of Hox genes:Gave rise to larger brains,

enhancing smell and vision.Aquatic gnathostomes have a

lateral line.

TetrapodsTetrapods

Animals with four feet derived from the lobe fins.

Made the move to land.Their body changed to allow for

walking.

Animals with four feet derived from the lobe fins.

Made the move to land.Their body changed to allow for

walking.

AmniotesAmniotes

Tetrapods (mammals and reptiles, including birds) with adaptations for land.

Amniotic egg.Contains extraembryonic

membranes that protect the embryo.

Function in gas exchange, waste storage, and nutrient exchange.

Tetrapods (mammals and reptiles, including birds) with adaptations for land.

Amniotic egg.Contains extraembryonic

membranes that protect the embryo.

Function in gas exchange, waste storage, and nutrient exchange.

The AmnionThe Amnion

Bathes the embryo and acts as a shock absorber.

Eggs contain either a calcareous shell or a leathery shell to protect against dehydration.

Expanded habitat choices.

Bathes the embryo and acts as a shock absorber.

Eggs contain either a calcareous shell or a leathery shell to protect against dehydration.

Expanded habitat choices.

AmniotesAmniotes

Also acquired less permeable skin, a ribcage to ventilate the lungs, and a more upright or elevated stance.

Also acquired less permeable skin, a ribcage to ventilate the lungs, and a more upright or elevated stance.

Derived Characters of Mammals

Derived Characters of Mammals

Mammary glandsBody hairLive youngEndothermicDifferentiation of teeth

Mammary glandsBody hairLive youngEndothermicDifferentiation of teeth

MonotremesMonotremes

Platypus, ant eaters.Found only in Australia and New

Guinea.Lay eggs that hatch.The mom secrets milk from a gland

in the belly.No nipples, the hatchlings suck

milk from the mother’s fur.

Platypus, ant eaters.Found only in Australia and New

Guinea.Lay eggs that hatch.The mom secrets milk from a gland

in the belly.No nipples, the hatchlings suck

milk from the mother’s fur.

MarsupialsMarsupials

Opossum, kangaroos, and koalas.High metabolic rate, nipples, live

young.Embryo partially develops in the

uterus.When born, it completes its

development in the mother’s pouch.

Opossum, kangaroos, and koalas.High metabolic rate, nipples, live

young.Embryo partially develops in the

uterus.When born, it completes its

development in the mother’s pouch.

EutheriansEutherians

These are the placental mammals.High metabolic rate, nipples, live

young.Longer period of gestation.Embryonic development is

completed within the uterus.

These are the placental mammals.High metabolic rate, nipples, live

young.Longer period of gestation.Embryonic development is

completed within the uterus.