Download Kingdom Animalia Phylum Chordata

Kingdom Animalia
Phylum Chordata
The vertebrates and their relatives
Figure 23.02
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)
Characteristics of Chordates
Phylum Chordata
Subphylum
Urochordata
tunicates
Subphylum
Cephalochordata
lancets
Subphylum
Vertebrata
Agnathans
Fish
Sharks
tetrapods
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
5,200 species
Vertebrate Higher
Classification

Superclass Agnatha - without jaws



Class Myxini – hagfishes
Class Cephalaspidomorphi – lampreys
Superclass Gnathostomata – with jaws







Class Chondrichthyes – sharks, rays, chimaeras
Class Actinopterygii – ray-finned fishes
Class Sarcopterygii – lobe-fin fishes
Class Amphibia – frogs, salamanders
Class Reptilia – snakes, lizards, crocodiles
Class Aves - birds
Class Mammalia - mammals
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
Possible evolution of 1st fish
1st fish
lancelet
Proto-vertebrate
Tunicate larvae
Adult tunicate
Early Chordate ancestor may have given rise to 1st vertebrate
Pikaia
Burgess Shale Fauna
Cambrian
540-500 mya
Groups of Extant Fishes
• Class Cephalospidomorphi – lamprey
• Class Myxini – hagfishes
• Class Chondrichthyes – cartilaginous
fishes
• Class Osteichthyes – bony fishes
Agnatha (jawless fishes)
• Lack: paired fins, scales,
& well developed
vertebrae
• Hagfish (slime eels)
– Mucus for protection
– Feed on decaying flesh
• Lampreys
– Parasitic
– Anadromous
• Marine adults, breed in
freshwater
– Vampire fish
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,
catfish, Larghemouth 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
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 two chambered heart and closed circulation
Body Systems of Fishes
• Fish digestive systems are similar to that
of humans
• Excretory system is slightly different
• Ammonia is excreted by diffusion of water
through gills and by use of kidneys
Body Systems of Fishes
**How does the action of peeing differ in a
marine environment vs fresh water?
I got to go pee!!!
Osmoconformers
vs.
Osmoregulators
What is the difference?
Osmotic Challenges
• Osmoregulation- regulates solute
concentrations and balances the gain
and loss of water
• Osmoconformers, consisting only of some
marine animals, are isoosmotic with their
surroundings and do not regulate their
osmolarity
• Osmoregulators expend energy to control
water uptake and loss in a hyperosmotic or
hypoosmotic environment
Hagfishes
• Osmoconformers
• Only vertebrate that is isotonic to seawater much like marine invertebrates
Osmoregulators
• Aquatic vertebrates - gills are chief organs of
excretion/osmoregulation
• Kidneys first evolved as osmoregulatory organs in
fishes to remove water (freshwater) or conserve
water (marine)
Do I
drink
water
?
Do I
drink
water
?
Describe
my pee.
Describe my pee.
Figure 44.3
(a) Osmoregulation in a marine fish
Gain of water
and salt ions
from food
Gain of water
and salt ions
from drinking
seawater
Excretion
of salt ions
from gills
Osmotic water
loss through gills
and other parts
of body surface
Excretion of salt ions and
small amounts of water in
scanty urine from kidneys
(b) Osmoregulation in a freshwater fish
Gain of water
and some ions
in food
Key
Water
Salt
Uptake of
salt ions
by gills
Osmotic water
gain through
gills and other
parts of body
surface
Excretion of salt ions and
large amounts of water in
dilute urine from kidneys
Body Systems of Fishes
**How does the action of peeing differ in a
marine environment vs fresh water?
– Salt water fish lose water and thus conserve
bodily fluids by having concentrated urine
– Fresh water fish gain water and to have dilute
urine
– Fish that move from fresh to salt water alter
their kidney function to adapt to tonicity!
Fish Senses
• Fish exhibit
cephalization (brain)
• 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?
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