Transcript Animal Kingdom Vertebrates Vertebrate History   Overview: Half a Billion Years of Backbones By the end of the Cambrian period, some 540 million years ago –  An.

Animal Kingdom
Vertebrates
Vertebrate History
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Overview: Half a Billion Years of Backbones
By the end of the Cambrian period, some 540
million years ago
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An astonishing variety of animals inhabited Earth’s
oceans
One of these types of animals
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Gave rise to vertebrates, one of the most successful
groups of animals
What’s with the Name?
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The animals called vertebrates
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Get their name from vertebrae, the series of
bones that make up the backbone
Vertebrate Diversity
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There are approximately 52,000 species of
vertebrates
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Which include the largest organisms ever to live
on the Earth
Vertebrates have
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Vertebrae enclosing a spinal cord
An elaborate skull
Fin rays, in aquatic forms
Fish: The First Vertebrates
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The earliest fossils are
from 500 million years
ago.
Highly evolved/adapted
for living in water
environments.
Water Presents Unique Challenges
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How to move around
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How to get air
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How to float
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How to sense what is around me
Movement
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Fish Shape- Fish are streamlined to
minimize resistance.
Fish Skin- It is slimy, covered with mucous
secretions to reduce friction
Fish Paddles- The fins of fish allow for
movement.
Gas Exchange
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Water has 2.5% the free oxygen as air.
Gills- Need to be very efficient at gas
exchange.
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They are composed of lots of tiny folds called
lamellae.
Capillary beds move in opposite direction to water
flow allowing for countercurrent exchange of
oxygen.
Gas Exchange (Cont.)
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Water needs to be constantly moved over the
gills.
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Ram Ventilation- Adaptation of swimming with
mouth open.
Operculum- A gill covering that can pump in
water.
How to float
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Floating/Sinking is
dependent on density.
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Float=Less dense than water
Sink=More dense than water
4 Methods for floating
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Low density oils
Low density bones
Fins
Pneumatic sacs- lungs or
swim bladder that can be filled
with air.
Sensory Functions
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Fish have eyes, nose, and ears
Additionally……
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Lateral line system- collection of sensory nerves
that run in a line along the sides of fish.
Can sense currents or predator/prey movements.
Electroreception-Detection of electrical fields
from nerves and muscles of the other organisms.
Class Agnatha
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(a- = not, without;
gnatho = jaw)
The lampreys.
Don’t have jaws,
often parasitic
The most primitive
form of fish with a
true vertebrate
Lamprey
Two Classes of Jawed Fish
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Class Osteichthyes “Bony Fish”
Class Chondrichthyes “Cartilage Fish”
Two different responses to selection
pressures.
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Each have advantages and disadvantages.
Class Chondrichthyes “Cartilage Fish”
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(chondro = cartilage; ichthys = fish)
Sharks and rays
They have a cartilage
skeleton, not bone.
Their backbone extends into their caudal fin
Class Osteichthyes “Bony Fish”
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(osteo = bone)
Bony fish.
24,000 Species
Operculum
Swim bladder or lungs
90% of members
fertilize externally.
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Lots of eggs
Class Chondrichthyes Cont.
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Advanced Electroreception
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They also fertilize
internally.
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Produce fewer eggs, less
young tend to die.
Lack operculum, lungs,
and swim bladder
Class Amphibia
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(amphibia = living a
double life)
They were the first
land
vertebrates.
Most either go back
and forth from land to
water or undergo
metamorphosis.
Amphibian History
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Early fossils of now extinct amphibian
ancestors date back 400 million years.
Modern amphibians represent 3,000 species
on all continents except antartica.
There are three Orders
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Caudata
Anura
Gymnophiona
Order Caudata
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Salamanders and newts
Possess a tail throughout life, little leg
development, most have internal fertilization,
live in forest floors and caves constant
moisture and temperature.
Larvae similar to adult but smaller with
external gills and a tail fin.
Order Gymnophiona
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Caecilians
(Rare)160 Species in tropical regions
Worm-like burrowers that feed on
invertebrates in the soil.
Retractile tentacles between their eyes and
nostrils may give sense of smell.
Skin covers eyes (probably blind)
Internal fertilization
Order Anura
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4,000 species of frogs and toads
Can live in most aquatic
environments
Adults highly developed hind limbs;
no tails
Larval stages (tadpoles) have tails,
no limbs, and are omnivores.
Primarily external fertilization
Frog and toad-less scientific “toad”
normally means dry and warty skin
and are more terrestrial than “frogs”.
Skin
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Skin is crucial for gas exchange 30-90%.
(cutaneous respiration)
Buccal pump-when mouth and pharynx
muscles push air into lungs.
Skin also used to regulate temperature
(exothermic)
Skin also regulates water (osmoregulation)
Nervous System
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Amphibians have highly
developed eyes.
Used for catching prey.
Nicitating membrane used
for keeping eye clean and
refracting light.
Anura has developed
hearing for sensing prey
and mating calls.
Population Decline
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Amphibian populations declining around the
world.
Larval stages highly sensitive to environment
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pH changes (acid rain)
UV light (depleted ozone)
Habitat destruction (human overpopulation)
Class Reptilia
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(reptili = creeping)
Dinosaurs (dino = terrible ),
snakes, turtles, crocodiles,
and lizards.
Reptiles have scales and are
dry to the touch.
Reptiles are exothermic
(exo = out, outside), they
maintain body temperature
through external means such
as sunning on a rock or
seeking shade.
Class Reptilia(Cont.)
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Dry skin with epidermal scales
Skull with one surface point touching
vertebrate
Respiration via Lungs
Internal Fertilization
True amniotic egg-not only resistant to
drying, but hard leathery shell and yolk for
nutrients.
Water conserving Kidneys
Reptile Diversity and Lineage
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There are 17 Orders of Reptiles, however
only 4 still contain living members.
Some of the now extinct lineages have given
rise to Dinosaurs, Birds, and even Mammals.
The evolutionary advancements of reptiles
allowed future species to be independent of
water environments and live exclusively on
land.
Classification of Living Reptiles
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Class Reptilia
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Order Testudines
Order Crocodylia
Order Sphenodontida
Order Squamata
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Suborder Sauria-The Lizards
Suborder Serpentes-The Snakes
Suborder Amphisbaenia-Worm Lizards
Order Testudines (Turtles)
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There are approximately 300 species
They are characterized by bony shell, limbs
that join the ribs, and keratinized beak
instead of teeth.
Lay eggs, but don’t protect or provide
parental care
Long time to Mature (Up to 8 years)
Long life span (For some 100+ years)
Order Crocodylia (Crocodiles)
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21 species that were derived from
archosaurs (like dinosaurs).
Unique skull openings in front of
eye, triangular eye sockets,
laterally compressed teeth.
Swallow prey whole
Lay eggs but display parental care
and nesting.
Order Sphenodontida (Tuataras)
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Two surviving species.
Look like lizards but are far
different, have characteristics of
200 million year old fossils.
There teeth characteristics and
structure are different from
reptiles.
Asymmetrical organisms do not
develop complex communication,
sensory or motor functions.
Live in remote islands off of New
Zealand
Order Squamata
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By far the
most diverse
and numerous
Orders of
Reptiles.
Divided into 3
Suborders
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Lizards
Snakes
Worm Lizards
Suborder Sauria (The Lizards)
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4500 Species of Lizards
Have 2 pairs of Legs
Very Diverse
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3 cm to 3 m in length
Some lay eggs, some
don’t
Camoflauge
Long Tongues
2 are venomous
Suborder Serpentes (The Snakes)
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2900 Species (Most not dangerous 300
ven.)
How many people die each year of snake
bites?
More than 200 vertebrate and ribs for
flexibility
Upper and lower jaws open independently
Eye differences between lizards and
snakes
Thin elongated body has resulted in loss of
lung and kidney (1 of them)
Suborder Amphisbaenia-Worm
Lizards
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135 Species
They are limbless burrowers
Distinguished from all other vertebrates by
the presence of 1 tooth in upper jaw
Can move forward or backward in burrows
and feed on small insects.
Also lay eggs.
Reptile Adaptations
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Reptiles are the first
vertebrates to live
exlusively on land.
Many adaptations to
not only survive, but
flourish
Reptilia-Dry skin with
scales, lungs,
specialized kidneys,
internal fertilization
and amniotic eggs.
External and Locomotion
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Skin has no respiratory function.
All reptiles shed the outer layer of their skin
periodically, called ecdysis.
Bones have higher density (more ossification)
Ribs and vertebrate are more numerous and flexible
allowing for movement.
Autotomy-Tail loss that allows lizards to escape from
a predator’s grasp. Later regenerated.
Nutrition and Digestion
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Most reptiles carnivores; few turtles are omni or
herbivores.
Lizards have sticky far reaching tongues for catching
prey. Chamelion tongue exceeds body length.
Jaw in snakes are loosely attached and can open
independently of each other. Great for swallowing
prey
Venom is secreted from modified salivary glands
called fangs. It contains mixture of neurotoxins
(respiratory paralysis) and hemotoxins (destroys
blood vessels).
Circulation, Gas Exchange and
Temperature Regulation
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Bigger and longer bodies means the need for
higher blood pressure to provide blood to all
parts.
Can migrate together in hibernaculums.
Many reptiles can control blood flow.
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Oxygen conservation
Temperature regulation
Nervous System
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Highly developed nervous system allows for special adaptations
that fit each species role.
Pit Organs-Heat sensitive organs that can detect hidden warm
blooded prey.
Parietal Eye-Found in some reptiles (tuataras) and is a
photoreceptor for detecting light.
Sea Turtles-Can detect magnetic field and return to breeding
grounds that are 3,000 km away and 15 years old.
Jacobson or vomeronasal organ-Organs that provide a highly
advanced sense of smell. Work in conjunction with the forked
tongue of squamates.
Excretion and Water Regulation
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Reptiles have metanephric kidneys. They are
specialized to reduce water loss. (More blood
filtering units called nephrons)
In fact, uric acid is secreted in paste like form as
waste.
When available reptiles store large quantiites of
water under skin and in bladder.
Many lizards have salt glands under eyes to secrete
salt.
Reproduction
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Internal fertilization
True amniotic egg-Resistant to dessication and has
a hard shell with yolk.
Sperm storage-Some female reptiles can store
sperm for 4-6 years until conditions are good for
offspring.
Parthenogenesis-Very special kind of reproduction in
which one parent produces genetically identical
offspring. Six species of lizards one of snakes. No
males found in population.
Class Aves
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(avi = a bird) is the birds.
Key characteristic of birds = feathers.
Birds’ bones are light weight for flight.
Birds are
endothermic
(endo = within,
inner) they control
their body temperature from within.
Class Aves (The Birds)
What makes something a bird?
Bill; No teeth
Light and Hollow Bones
Endothermy
Appendages modified as feathered wings
Flexible Neck
8500-10,000 Species (27 Orders)
Birds: Reptiles By Another Name?
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Lots of similarities between reptiles and birds
Structural: Single point of articulation
between skull and vertebrae, one ear ossicle,
lower jaw, and other skeletal similarities.
Physiological: Nucleated rbcs, similar liver
and kidney functions.
Behavioral: Nesting and care for young
(Crocodylia)
So Where Did Birds Come From?
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Ancient Archosaurs-lineage shared by
dinosaurs and crocodiles.
Looks like more closely related to dinosaurs.
Fossil evidence points to dinos—dozens of
fossils were found bearing feathers.
Theropods specifically; these were bipedal
dinos like T-Rex.
Archaeopteryx: Ancient Bird????
Illustration from the fossils found of this ancient bird/reptile. It was
initally called the link between reptiles and birds, but this is very
controversial. Fossils date back to 150 million years. Picture on
page 343 of book.
Bird Feathers: What are they good
for?
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Today: Flight Originally: Not Flight
Early fossils with feather had too dense of bones and
wrong shapes for flight.
They were probably used for:
Insulation/Temperature Regulation
Water repellency
Courtship
Camoflauge
Balancing Devices
Bird Feathers
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Flight: Provide lift and insulation
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Courtship, Waterproofing, balance, etc.
2 Broad Types of feathers:
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(High temperature necessary for high metabolic rate)
Pennaceous Feathers
Plumulaceous Feathers
Preening of feathers is essential-keeps them clean,
rub oil for waterproofing, and “zip” back together for
flight.
Feathers molt as well.
Skeleton and Muscle
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Head is modified to function as “hands”
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Skull meets backbone at one point and neck is very flexible.
Teeth have been replaced by a bill.
Bones themselves are lightweight with tiny hollows
throughout.
Flight muscles can contract quickly and fatigue slowly
because of lots of mitochondria that make ATP
Interestingly, domestic chickens are bred together for
more “white meat” muscle which is good to eat, but poor
for flight because of low mitochondria and vascularization.
Bird Nutrition
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Bird’s have crazy high metabolisms and
need to eat a lot!
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Hummingbird wings 80 bps
Robin’s Heart rate 600 bpm
Bill and tongue are highly adapted for their
niche (role):
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Eagle for tearing prey
Woodpecker for tapping into trees
Humminbird tongue unrolls to get into flower
Bird Digestion
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Many birds have a crop,
which is a storage pouch
in the esophagus. Allows
them to digest in safety or
store to feed young.
Stomach has two parts:
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Proventriculus (glandular
stomach)-secretes
digestve enzymes.
Ventriculus (gizzard)muscular wall to crush
seeds.
Circulation and Gas Exchange
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Heart: Relatively large for size, rapid heart
rate, and unlike reptiles complete separation
of oxygenated and non-oxygenated blood.
Respiratory System: Most advanced of all
tetrapods
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2 Cycle inhale/exhale, which maximizes oxygen
intake.
Explains how birds fly at high altitudes.
Thermoregulation
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Maintain a body temperature of 38-45
Celsius. (100-113 F)
Feet of a bird have no feathers and poor
blood supply. They can drop to near
freezing.
During flight large amounts of heat are
generated. Birds will “pant” and open
mouths to allow for evaporative heat loss.
Sensory Functions
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Vision is important to birds
Have a unique double focusing mechanism.
Can change the curvature of their lens and
cornea to allow for maximal focus on prey
during flight.
Have nicitating membrane
Poor sense of smell
Similar hearing to human
Excretion
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Birds need to conserve water, much like
reptiles.
Secrete Uric Acid
Store and reabsorb water in bladder
Have salt glands for salt secretion
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This can allow sea birds to drink salt water.
Bird Mating
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Bird reproduction is complex, it involves establishing
territory, finding mate, constructing nests, incubating
eggs, and feeding young.
All birds are oviparous
Birds only chase off others of the same species
during territory establishment, threats are frequent,
but fights rare.
A clear territory ensures safe nesting, food supply
and better chance of offspring survival.
Bird Mating Behaviors
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Most birds are monogamous for a breeding season
and some for life. However, polygynous and
polyandrous occurs depending on species.
Monogamy-Having one mate.
Polygynous-Having more than one female.
Polyandrous-Having more than one male.
Each has its own advantages and disadvantages.
Which gives most young? Which gives best chance
of survival?
Bird Nesting
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Nesting behavior is species specific.
Eggs need to be incubated for 10-80 days.
Collection of eggs and young for a bird is called a
clutch.
Lifespan in captivity is 20 years and on average in
wild most birds live 1 to 2 years.
Offspring come in two forms:
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Altricial-Entirely dependent on parents.
Precocial-Young are alert and lively at hatching. Normally
covered in feathers.
Migration and Navigation
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Birds will migrate long distances in order to avoid
environmental extremes.
Non-stop fliers will store 50% of their body weight in
fat.
Normally involves north and south movement.
Migration occurs due to species specific physological
cues and environmental cues.
Most common cue is period of daylight.
They navigate based on visual, auditory and
sometimes magnetic cues.
Class Mammalia
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(mamma, mammil =
teat, nipple)
Mammals.
Key characteristics =
presence of fur/hair and
mammary glands, which
produce milk for young.
Most mammals bear
live young
When/How Did Mammals Arise?
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The Tertiary period about 70 million years ago.
This coincided with the reptile extinctions
(dinosaurs).
Dinosaurs being gone “opened the door” to lots of
niches….food and habitat sources not being used.
May have initially been nocturnal to avoid potential
large reptile predators.
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Living at night would have made endothermy very
important.
Class Mammalia
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Mammary Glands
Hair
Most have live birth
Diaphragm
Well developed ear
Heterodont
Four Chambered Heart
Well developed cerebral
cortex
Sweat and scent glands
Endothermy
3 Main Infraclasses
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Monotremes-They are oviparous and have a cloaca. Ex. Duck
Billed Platypus
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Cloaca-Common opening for digestion, reproduction and
excretion.
6 Species found only in Australia and New Guinea
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Metatheria-Viviparous with a primitive placenta. Young are
born early and carried in a pouch. (Marsupials)
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Eutheria-Complex placenta; young are well developed before
birth. (Placentals)
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By far the most numerous and diverse group.
All the Orders we are about to talk about fall under this “Infraclass”
How Well Adapted Are Mammals?
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Mammals are naturally
found on every continent
except Antartica.
This means we have
mammals that can live in
the cold, heat, dry, wet,
forest, and plains.
We have limbs that with
claws, hooves, wings, or
flippers.
Mammalian Skin, A Hairy Situation
Hair is a derivative of the epidermis and is
unique to mammals.
 An animals coat is called pelage.
 Hair is used for temperature regulation,
sensory perception,
and camoflauge.
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External Adaptations (Cont.)
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Claws are present in mammals.
They are used for motion or defense.
They have evolved for each species
purpose: hooves and nails
Lechien’s Feet (that’s why he wears those big shoes!)
Glands, a Stinky Situation
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Scent/Musk Glands-Found around the face, butt and
feet. Secrete pheromones involved in defense, sex,
and territorial behaviors.
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Do Humans have pheromones?
Sebaceous glands-Secrete oil for hair waterproofing
and lubrication.
Sudoriferous glands-Sweat glands for temperature
regulation.
Mammary glands-Function in female to provide
young with food and antibodies.
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Advanced form of parental care.
Mammalian Skull and Teeth
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Scientists can tell mammal skulls from reptiles from the jaw
bone.
In reptiles the jaw joins with two small bones at the rear, but for
mammals they are gone and it joins in just one spot.
Mammals have up to 4 kinds of teeth
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Incisors: In front for gnawing.
Canines: Tearing
Premolars: Chewing
Molars: Used for grinding
The number of each kind of teeth can help classify a mammal.
Ex. Human 2,1,2,3 Beaver 1,0,1,3
If you knew an animal was 1, 0, 2, 5 what do you probably
know about that animal? Or 3, 3, 1, 0?
Digestion
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Each mammal species has uniquely
adapted digestion for its diet.
Herbivores: Eat lots of cellulose,
which is not normally digestable to our
bodies.
They have a cecum: A specialized
pouch that stores bacteria that break
down the cellulose.
Cow, deer, and sheep have 4
stomachs each at different stages of
fermentation.
Circulation and Gas Exchange
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Like birds we have a 4 chambered heart that
separates oxygenated and non oxy. blood.
The best advancement for mammals is the
exchange of air, nutrients, and waste to/from fetus
through the placenta.
Fetal and maternal blood vessels are intimately
close, but no mixing occurs.
Unlike reptiles or birds, the diaphragm separates
chest and abdominal cavity and is a muscle that
contracts for mammal breathing
Endothermy
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Most mammals live in
environments that require both
heating and cooling.
Heating
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Shivering: Involuntary muscle
contractions.
Cell Metabolism: Breakdown of
food.
Cooling
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Sweating: Evaporative cooling on
skin.
Blood flow: Blood can be directed to
surface.
Nervous System
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Highly evolved senses and brain
3 Middle ear ossicles
Vision-Controlled by Rods(light, no color)
and Cones (color)
Most mammals have poor color vision and
lots more rods than cones.
How does this support the idea that early
mammals were nocturnal?
Excretion and Territory
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Mammals have
metanephric kidneys,
but secrete urea (more
watery than reptile uric
acid)
Lots of mammals use
urine to mark territory,
access sexual
readiness, and even
fitness of individuals.
Behavior
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Behavior is important for mammal survival.
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Grooming-Reinforces social bonds and prevents
disease.
Sounds-Can warn of predators or invoke breeding
Bristling of fur-Serve as warning.
Reproductive Cycles & Strategies
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Most mammals have a set time in which their eggs are
mature and ready for fertilization.
This reproductive cycle is called the estrus cycle.
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Monestrus-A single time of year. Ex. Bears
Diestrus-Twice a year. Ex. Domestic Dog
Polyestrus-Many times. Ex. Rats every 4 days
Two strategies
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Delayed fertilization-Storing sperm and waiting to fertilize.
Embryonic dispause-Fertilization has occurred but embryo
development is temporarily paused.
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Why are these two strategies a good thing for some mammals?
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