VERTEBRATES
Ch. 25 & 26
Life
Birds
 Mammals

What are vertebrates?
Animals with a backbone
 Examples: fishes, frogs, turtles, snakes,
birds, alligators, mammals, etc.

Vetebra comes from the
Latin word vertere,
meaning “to turn”
Phylum Chordata

Chordates are named for an embryonic
structure
– The notochord is a flexible rod that extends through
much of the length of the body
 Most chordates are vertebrates, but
 There are two groups of invertebrates
that are chordates (tunicates &
lancelets)
Vertebrates are Chordates

Vertebrates are animals with a skull and a backbone
– An endoskeleton
In vertebrates, only remnants of the notochord remain
 Example: the cartilage discs in your
backbone

Most vertebrates have paired limbs

What is the importance of:
Skull?
Backbone?
Other important features

Hinged Jaws
– Importance?
Vertebrates

Hagfish and lampreys
 Do not have hinged jaws or paired limbs
Vertebrates

Fishes
– Have hinged jaws
– aquatic
Tetrapods:
Amphibians, reptiles, birds, mammals
 Tetrapods (“four footed”) have 2 sets of
paired limbs

 This allowed them to??

Snakes are tetrapods!
 They evolved to become legless
Activities
1) Finish grasshopper dissection & turn in.
 2) pHSuccessnet.com

– Ch. 25 webquest
– Activity 25.1
FISHES
The 1st jawed vertebrates.

2 Categories:

Cartilaginous fishes – Chondrichthyes
 Skeletons are flexible and made entirely of cartilage
 Sharks and rays

Bony fishes
 Skeletons contain bone hardened by calcium
deposits
Bony Fishes
Stiff skeleton made of calcium
 Gills to extract O2 from water

– Operculum- flap that covers the gills
- pumps water over the gills

Lateral line system
Bony Fishes

Stiff scales made of bone

The outer mucus allows fish to glide more
easily through the water

Most are carnivores
 Some feed upon plankton or algae (seaweed)
Bony Fishes

Air Sac
– “swim bladder” makes fish more buoyant
– Also aids in hearing by transmitting vibrations

Heart ---> 2 Chambers
 The ventricle (1) pumps blood to the gills
 The atrium (2) receives blood returning from the body
2 Chamber Heart

One way circuit

Very basic

Much slower than
land vertebrates
Video

Life Science: Fish and Amphibians
Review
1) What is the major difference between
cartilaginous and bony fishes?
 2) Describe the function of the lateral line
system.
 3) List the general characteristics of bony
fishes.
 4) List and contrast the 3 classes of bony
fishes.

Perch Dissection
Perch Dissection
The First Tetrapods

Amphibians are
descendants of four limbed
ancestors that were fully
aquatic 400 mya
– Limbs and legs evolved in
fishes– moved to land (50
million years)

Leg-like limbs allowed for
movement through dense
marine vegetation
The First Tetrapods

Acanthostega have gill structures, but
amphibian-like limbs
Amphibians

Amphibios= “living a double life” in Greek

Many live in their larval stage in water and adult
stage on land
 Eggs do not have shells so are easily dried out
 Water is often necessary for laying eggs

Adults generally:
 Have Lungs
 Have moist skin without
scales
Stage of Development

Tadpoles --> the larvae of amphibians
 Legless aquatic plant-eaters with:
 Gills, lateral line system, long tail

Metamorphosis into adult form leads to:




Lungs in place of gills
Eardrums
No lateral line system
4 legs
***Some amphibians do not have a terrestrial
stage, some amphibians do not have an aquatic
stage
Other characteristics

Moist skin often assists lungs with gas
exchange
 May also contain poison glands

Amphibians have a 3-chambered heart
 Remember fish have 2 chambered heart

Allows for 2 pathways of
blood flow
 One to the lungs and
skin for gas exchange
 One to the other tissues
 Advantage??

The Atria collect blood
returning to heart

Ventricle pumps blood out
Amphibian Diversity

about 8% of vertebrates

Frogs
– insect eaters
– Toads are terrestrial frogs

Salamanders
– insect eaters

Caecilians
 Legless & blind; burrow in soil
Video

Life Science: Fish and Amphibians
General Characteristics of
Amphibians?
1)
 2)
 3)
 4)
 5)


What if they were forced to live on land
and have no access to water?
AMNIOTES

Amniotes- reptiles, birds, mammals

General Characteristics:
– Live on land (do not need water)
– Amniotic egg
– Internal fertilization
– Water-tight skin
Amniotic Egg
Waterproof egg with a shell
 Amnion- protects embryo from drying out

Water-tight Skin

Enriched with keratin
– Prevents dehydration
Reptiles- scales
 Birds- feathers
 Mammals- nails, hair, horns

Reptiles
Reptile Characteristics
Water-tight, scaly skin that molts
 Lungs
 Lay eggs
 Cold-blooded
(ectotherms)

Komodo Dragon Hunting a Water
Buffalo

http://dsc.discovery.com/tv/life/episodes.h
tml
BIRDS
Ancestor- dinosaur
 Endothermic amniotes
 Adaptations for flight:

– Wing shape
– Feathers (also for insulation)
– Several weight-reducing features
Review of Frog Dissection
Where is the tympanic membrane?
 How can you tell a male from a female?
 What is the cloaca?
 What is the purpose of the fat bodies?
 What are 3 differences between reptiles
and amphibians?

Wing Shape

Airfoil-shaped wings
Air-sac System
Function with lungs for respiration
 Helps supply high level of O2 that
supports a high metabolism.
 Also reduces density of bird

Weight-Reducing Features
Air-sacs
 Honey-combed bones
 Absence of some internal organs

Circulatory System
Efficient oxygen delivery
 4-chambered heart

– Adaptation for active, endothermic lifestyle
MAMMALS

Mesozoic era- evolved from mammal-like
reptiles, therapsids
Mammal Characteristics
Endothermic
 Mammary glands- milk
 Hair- insulation
 Lungs with diaphragm
 4-chambered heart
 Internal fertilization

Mammal Diversity

Monotremes- lay eggs, cloaca
Mammal Diversity

Marsupials- “pouched mammals”
Mammal Diversity

Placental Mammals- Embryo completes
development within the uterus; placenta
forms & feeds embryo