Transcript Kingdom Animalia Phylum Chordata

Kingdom Animalia
Phylum Chordata
The vertebrates and their relatives
Phylum Chordata
• Characteristics of a chordate
– A dorsal hollow nerve cord (spinal cord in
vertebrates)
– A notochord (most vertebrates only have a
notochord during development – becomes the
backbone in vertebrates)
– Pharyngeal Pouches (develop into gills in fish
and amphibians)
– Muscular Tail (disappears in humans)
Subphylum Urochordata
• Tunicates (also known as “sea squirts”)
– Look similar to other chordates during
development, but completely different as
adults
Subphylum Cephalochordata
• Lancelets: live in the ocean with their body buried in
sand
– Have a definite mouth and no jaws
– Long pharynx with up to 100 gill slits
– Breathe through their body surface
– Have a simple digestive system, heart, and closed
circulation
– Use paired muscles to move
Subphylum Vertebrata
• 99% of chordates are vertebrates
– Fish
– Amphibian
– Reptiles
– Birds
– Mammals
24,000 species
4,000 species
6,000 species
10,000 species
4,500 species
Fishes
• Aquatic vertebrates characterized by:
– Fins (Movement)
– Scales (Protection)
– Gills (Breathing)
• There are fish with exceptions!
– Can you name any?
Fish Evolution
• Fish were the first vertebrate to evolve
• Evolved about 540 mya
– Were jawless and covered in armored plates
• Devonian Period = Age of the Fishes
– Fish developed both jaws and fins at this time
Body Systems of Fishes
• Fish feed in a variety of ways including parasites,
carnivores, herbivores, etc.
• Most fish breathe using gills
– Gills are feathery filaments containing a network of capillaries to
increase surface area for CO2 and O2 exchange
• Fish have closed circulation
Body Systems of Fishes
• Fish digestive systems are similar to that
of humans
• Ammonia is excreted by diffusion of water
through gills and by use of kidneys
– Salt water fish conserve bodily fluids by
having concentrated urine
– Fresh water fish have dilute urine
– Fish that move from fresh to salt water alter
their kidney function to adapt to tonicity!
Fish Senses
• Fish exhibit
cephalization
• Many fish have
Chemoreceptors for
an extraordinary
sense of taste and
smell
• Lateral Line System –
allows fish to sense
movement and
vibration
Fish Senses
• Swim Bladder – adjust buoyancy
– How does pulling a fish from 40 feet of water
affect the size of its swim bladder?
Fish Reproduction
• Oviparous – egg laying; includes both
internal (some sharks) and external (most
fishes) fertilization
• Ovoviviparous – eggs develop inside
mother’s body and are nourished by egg
yolk; young are born alive
• Viviparous – the mother’s body nourishes
the developing young which are born alive
Groups of Fishes
• Class Cephalospidomorphi – lamprey
• Class Myxini – hagfishes
• Class Chondrichthyes – cartilaginous
fishes
• Class Osteichthyes – bony fishes
Lamprey and Hagfishes
• Are jawless fishes
– Have mouths of soft tissue and no true teeth
• Have no bones
• Are the only vertebrates that do not have
vertebral columns as adults
Lamprey
• Are filter feeders as larvae and parasites
that suck blood and tissues of fish as
adults
Hagfishes
• Feed on dead and dying fish using a
toothed tongue to scrape a hole in the
fishes side
• Secrete large amounts of slime
• Have 6 hearts and an open circulatory
system
Cartilaginous Fishes
• Includes sharks, rays, skates, sawfishes,
and chimaeras
• “Chondros” = Greek word for cartilage
• A typical shark has 3000 teeth arranged in
6 to 20 rows
• Not all are carnivores, the largest sharks
are filter feeders
• Some have flat teeth for crushing mollusks
and crustaceans
Bony Fishes
• Skeletons are made of calcified bone
• Includes fish we are most familiar with:
Sunfish, Muskellunge, Northern Pike,
Walleye, Smallmouth Bass, etc.
Fish Ecology
• Some fish can live in both salt water and
fresh water
– Anadromous Fishes – spend most of their
life in the ocean but move to fresh water to
breed
– Catadramous Fishes – spend most of their
life in fresh water but move to the ocean to
breed
Class Amphibia
• Amphibians gave rise to all other land
vertebrates
• Amphibian means “double life”
– As larvae they are typically aquatic filter
feeders or herbivores breathing through gills
– As adults most species are terrestrial
carnivores that breathe through their moist
skin and have lungs
Adaptations to Life on Land
• As the amphibians developed in the late
Devonian Period 360 mya they needed to
adapt to terrestrial life
– Keep from drying out
– Breathe using lungs, not gills
– Bones in limbs allow movement
– Ribs to support and protect internal organs
• Amphibians dominated the Carboniferous
Period 345 to 285 mya
Amphibian Body Systems
• Amphibians have a well developed
digestive system similar to that of humans
• As most amphibians develop lungs as
adults, some are lung-less and only
breathe through their skin
• They have closed circulation and a 3
chambered heart with a double loop
system similar to that of a human
• Ammonia is disposed of in urine through
the use of kidneys
Amphibian Reproduction
• Most amphibians lay their eggs in water;
fertilization is external
• Some salamanders fertilize internally
Amphibian Reproduction
• In most cases of external fertilization, the
male will attach itself to the female. Eggs
and sperm are released simultaneously
and encapsulated in a jelly that attaches to
aquatic plants.
• The jelly nourishes the developing
embryos
• Tadpoles hatch and metamorphose into
adults
Amphibian Reproduction
• Most amphibians
abandon their eggs
once they lay them.
• Some care for both
eggs and young
• Some incubate their
eggs in unusual
places: in their mouth,
on their back, or in
their stomach
Amphibian Senses
• Amphibians have a well developed brain
and spinal cord similar to that of a fish
• Eye’s are protected by a nictitating
membrane
• A tympanic membrane, or eardrum, is
located on either side of the head
• Many have a lateral line system similar to
that of a fish
Groups of Amphibians
• Order Urodela: Salamanders and Newts
• Order Anura: Frogs and Toads
• Order Apoda: Caecilians
Salamanders and Newts
• Have long bodies and tails
• Both adults and larvae are carnivores
• Most adults are terrestrial and live in damp
forests
• Some salamanders, such as mud puppies,
keep their gills and live in water all their
lives
Frogs and Toads
• Have the ability to jump
• Frogs have longer legs and can jump
farther than toads
• Frogs are closely tied to water; toads are
more terrestrial
Caecilians
• Least known of the amphibians
• Are legless and burrow in moist soil or
sediment
• Feed on small invertebrates such as
termites
• Some have scales
Amphibian Ecology
• Most are a great meal for birds and
reptiles
• Some have toxins to poison predators
• Some have bright colors to warn of their
toxins
• Some mimic the bright colors of others
and are harmless
Amphibian Ecology
• Amphibian populations are declining
worldwide due to several factors:
– Global Warming
– Decreasing Habitat
– Depletion of the Ozone
– Water Pollution
– Introduced Aquatic Predators
– Fungal Infections
– Increasing human population!
Class Reptilia
• Land vertebrates with a well developed
skull, a backbone and tail, and four limbs
– Exemptions: snakes have no legs, and turtles
have a shell formed of fused vertebrae?
• Can a turtle lose its shell?
Reptile Evolution
• The oldest reptile fossils date back to the
early Carboniferous Period some 350
million years ago
• Dinosaurs of the Triassic and Jurassic
Period ruled the earth until 65 million years
ago
Reptile Body Systems
• Reptiles are ectotherms – rely on
interactions with the environment to
control their body temperature
• Reptiles have well developed lungs, four
chambered hearts, and a well developed
brain and spinal cord
• Reptiles’ legs are rotated farther under
their body than amphibians allowing them
to carry weight and walk on land more
efficiently
Reptile Reproduction
• Internal Fertilization – males have a penis
to place sperm in the female’s cloaca
• Most are oviparous
– Turtles leave their nests unattended while
alligators protect their nest
• Some snakes are ovoviviparous
Reptilian Eggs
• Reptiles have amniotic eggs – named after
one of the four membranes around the
developing embryo
– Amnion: produces watery environment
around embryo
– Yolk Sac: contains nutrient rich yolk that
feeds embryo
– Chorion: allows gas exchange
– Allantois: stores waste
Groups of Reptiles
• Order Squamata: lizards and snakes
• Order Crocodilia: alligators, crocodiles,
caimans, and gavials
• Order Chelonia: turtles, tortoises,
terrapins
• Order Rhynchocephalia - tuataras
Lizards and Snakes
• Most lizards have legs, clawed toes,
external ears, and movable eyelids
• Some lizards do not have legs and look
more like a snake
Alligators, Crocodiles, and their
Relatives
• Long broad snout and
squat appearance
• Fierce carnivores
• Very protective of their
nests
• Alligators and Caimans
live only in fresh water
and almost exclusively in
North and South America
• Crocodiles live in both
fresh and salt water and
are native to Africa, India,
and Southeast Asia
Turtles, Tortoises, and Terrapins
• Turtles – live in or
near water
• Tortoises – are
terrestrial
• Terrapins – live in
brackish water
– Carapace: Dorsal side
of Shell
– Plastron: Ventral side
of Shell
Tuataras
• Tuataras are the only living member of the
Order Rhynchocephalia
• Beak headed reptiles that live on a few
small islands off the coast of New Zealand
• Differ from lizards as they lack external
ears and retain primitive scales
• They have a legendary “third eye” which is
part of a complex organs on top of the
brain – the function is unknown
Ecology of Reptiles
• Many are in danger due to loss of habitat
• Humans also hunt them for food, pets, and
their skins (for bags and boots)
• Many conservation efforts are underway,
but more are needed worldwide
Class Aves
• Characteristics of
most birds
– Maintain a constant
internal body
temperature
– Covered in feathers
– Have two legs for
walking and perching
– Front limbs are wings
– Most are adapted for
flight
Feathers
• Used for flight and warmth; several types
– Contour Feathers: provide the lifting force and
balance needed for flight
– Down Feathers: trap air close to the body and keep
the bird warm
– Powder Down: found on ducks and other birds that
live on or in water; release a fine powder that repels
water
Evolution of Birds
• Oldest known fossil is Archaeopteryx
which lived during the Jurassic Period 150
mya.
– Had teeth in its beak, a jointed tail, and toes
and claws on its wings
• Birds are very closely related to dinosaurs,
but scientists disagree on whether birds
evolved from dinosaurs – or- birds and
dinosaurs evolved from one common
ancestor
Body Systems of Birds
• Endotherms: can generate their own body
heat; warm-blooded
• Smaller birds must eat more in relation to
its size due to Surface Area to Volume
Ratio
Feeding habits of Birds
• They lack teeth and therefore do not chew
• Beaks are adapted to the types of food
they eat
• Bird Digestion
– Crop: enlargement of the esophagus used to
store food
– Gizzard: has muscular walls and small bits of
gravel used to grind food
Respiration
• Birds have very efficient
lungs that provide oxygen
rich blood during both
inhalation and exhalation
• Inhaled air enters
posterior and anterior air
sacs it then travels
through the lungs and is
exhaled
• Therefore the air flows
into the air sacs and out
of the lungs in one single
direction, always
providing oxygen rich air
Circulation and Excretion
• Two loop circulatory system, similar to that of
humans
• Ammonia is removed by the kidneys, converted
to high concentration uric acid and defecated
(bird droppings); similar to reptiles
Senses of Birds
• The brains of birds are very well
developed
– Birds can see color very well
– Birds can hear very well
– Smell or taste are not well developed
Bones and Muscles
• Most birds can fly. Others are adapted for
swimming and running
• Bones are light, strong, and adapted for
flight; many bones are fused to provide a
study base for flight adaptations
Bird Reproduction
• Both male and female reproductive tracts
open into the cloaca
• The sex organs, internal in both sexes,
increase in size during mating season
• Birds rub their cloacas together during
mating to transfer sperm
Eggs and Incubation
• Eggs are amniotic but unlike reptile eggs
have a hard outer shell
• Eggs must be incubated by the parents
since they are endotherms
• Young must be cared for after hatching
Groups of Birds
• There are nearly 30 different orders of
birds
• 60% of all birds worldwide are perching
birds
• Show many examples!
Ecology of Birds
• Birds are very ecologically important
– Hummingbirds are involved in pollination
– Some birds eat seeds without digesting them
and therefore spread the seeds
– Many birds keep insect populations in check
• Many birds migrate by guidance of stars,
Earth’s landmarks, and Earth’s magnetic
field
• Birds are good indicators of environmental
health; bird numbers dwindled with the use
of DDT
Class Mammalia
• Characteristics of mammals
– Endotherms
– Have mammary glands and nurse young
– Have hair
Evolution of Mammals
• The earliest mammals evolved about the
same time as the early dinosaurs but
remained in the shadows until the giant
reptiles disappeared
• First ancestors of mammals appeared
during the Permian Period about 290 to
250 mya
• First true mammals appeared during the
Jurassic Period 210 mya
Mammal Evolution
• When the continents
split about 60 mya,
three groups of
mammals were
isolated from one
another.
Staying Warm
• Animals have hair to help
insulate their bodies.
• They also have
subcutaneous fat to keep
them warm and many have
sweat glands to cool them
off.
• Smaller mammals have
higher metabolism than
larger ones in order to
create enough body heat to
keep warm.
• Mammals eat about 10
times as much food as a
reptile in order to stay
warm.
Comparison of Vertebrate
Forelimbs
• When comparing the bones and bone
structures of all vertebrates - birds,
amphibians, reptiles, and mammals – you
can see many of the same bones with very
similar functions
• Refer to Figure 32-7 in the text (Page 826)
Mammal Reproduction
• Internal Fertilization occurs in mammals
• Mammals are divided into three groups
based on methods of development and
birth
– Oviparous: egg-laying mammals are called
monotremes
– Viviparous: includes both placental mammals
and marsupials
Caring for Young
• All newborn mammals feed on their
mother’s milk
• Some newborns are helpless at birth and
must be cared for
• Others are able to see and walk within
minutes after birth
Monotremes
• Monotremes are the egg
laying mammals
• They share two notable
characteristics with reptiles
– Both the reproductive and
urinary systems open into
a cloaca
– “Monotreme” means
single opening
• Only three species of
monotremes exist today: they
are found in Australia and
New Guinea
– Duckbill Platypus and two
species of Spiny
Anteaters
Laying eggs and caring for young
• Monotremes lay eggs that are incubated
outside the body
• They hatch into young animals in about 10
days
• The young are nourished by their mother’s
milk that they lick from pores on the
mother's abdomen
Marsupials
• Marsupials give birth to live young that
complete their development in an external
pouch
• Examples include kangaroos, wombats,
koalas, and Tasmanian devils
• A short time after internal fertilization a
small embryo leaves the mother’s body,
crawls across the fur, and enters the
marsupium (pouch) where it attaches to a
nipple to nurse
Placental Mammals
• Placental Mammals are those that are
most familiar to us.
• Placenta – organ in placental mammals
through which nutrients, oxygen, carbon
dioxide, and wastes are exchanged
between embryo and mother
• Gestation – the time it takes from
conception to birth in mammals (can vary
from 2 weeks to 2 years depending on the
mammal)
Orders of Mammals
• There are 12 orders of placental mammals
• They are classified based on several
criteria including
– Feeding
– Teeth and Jaw Structure
– Foot Structure
– Brain Development