Chapter 34
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Transcript of Chapter 34
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.
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.