Transcript Phylum Chordata - Dr. Annette M. Parrott

Phylum Chordata
Subphyla Invertebrata & Vertebrata
from sea otters to sea squirts
Chordates
 pharyngeal slits - a series of openings that connect the inside of
the throat to the outside of the "neck". These often, but not always,
become the gills.
 dorsal nerve cord - a bundle of nerve fibers which runs down the
"back". It connects the brain with the lateral muscles and other
organs.
 notochord - cartilaginous rod running underneath, and supporting,
the nerve cord.
 post-anal tail - an extension of the body past the anal opening.
Invertebrate Chordates
 Urochordata: marine
sessile animals that feed
by filtering food particles
from seawater taken in
through their gill slits.
 Cephalochordata: a
dorsal nerve cord,
notochord and gill slits
Subphylum Urochordata:
 Tunicates & sea
squirts
 sessile, marine filter
feeders w/ tadpole like
larvae (comp,
embryology)
Anatomy of a Tunicate
Subphylum Cephalochordata
 Lacelets, Amphioxus
 notocord persists
through adulthood
Subphylum Vertebrata
 vertebral column. hollow bones
protecting nerve cord replace
notocord
 distinct head with skull and brain
 3 classes of fishes:
– Agnatha, chondrichthyes,
osteichthyes
 4 classes of tetrapods
 The Kingdom of Animalia,
Vertebrates: Common Types and
Their Unique Characteristics
Fishes (Ichthyes)
 Aquatic or marine
 respire with gills
 2 chambered single
looped circulatory
system
 plural can be fish or
fishes depending on
species
Fish Adaptations
Agnatha- “jawless fishes”
 Lampreys and
hagfishes
 Lack jaws and have
permanently open
rasping mouths
 scavengers &
predators of
osteichythyes
 unpaired fins
 cartilaginous
skeleton some
Class Agnatha
 "w/o jaws"
lampreys
and hagfishes
lampreys=anti-coagulant
 eel like, scaleless slimy
skin, hagfish eats inside out
 lack paired fins
 mostly cartilage skeleton
 no well developed vertebral
column
 notochord=major support
structure
 jaws form from gill arches
Chondricthyes- "cartilaginous fish."
 Sharks, skates, rays,
Members of the
Chondrichthyes all lack true
bone and have a skeleton
made of cartilage (the
flexible material you can feel
in your nose and ears). Only
their teeth, and sometimes
their vertebrae, are calcified
so they rarely fossilize
 Must swim to pass water
through spiracles, no swim
bladder
 Don’t seem to get cancer
Class Chondrichthyes
 Cartilaginous fishes, which




have flexible endoskeletons
made of cartilage rather than
bone.
Sharks have streamlined
bodies, but it sinks if it stops
swimming
Shark teeth evolved from the
jagged scales that cover the
abrasive skin.
A spiral valve within the
shark intestine increases
surface area.
The lateral line system runs
along the length of each flank
o the shark; sensitive to
changes in the surrounding
water pressure.
Osteichthyes- “bony fishes”
 Skeleton more or less bony,
vertebrae numerous;
 Skin with mucous glands and
embedded dermal scales;
 Fins median and paired with
rays of cartilage or bone. Mouth
with many teeth (some
toothless); jaws present.
Ray-finned fishes
 Respiration by gills supported
by bony gill arches and covered
by a common operculum.
 Swim bladder often present.
 Most species are oviparous and
fertilization is external.
 Catfish, Air Breathing
Catfish
Lobe-finned fishes
Class Osteichthyes
 Bony fishes: include ray-finned,




lobe-finned, and lunged.
Operculum- draws water into the
mouth through the pharynx and out
between the gills; allows bony fish to
breath while stationary.
Swim bladder- an air sac that helps
control the buoyancy of the fish
Most species are oviparous, which
means they lay eggs that hatch
outside of the mother’s body,
although some have internal
fertilization.
Lateral Line,
More Bony Fishes
 Ray-finned fishes- fins are
supported by long flexible rays,
modified for maneuvering,
defense; live in fresh water and salt
water.
 Lobe-finned fishes- have muscular
pectoral and pelvic fins supported
by extensions of the bony skeleton.
 Lungfishes- use their gills as the
main organs for gas exchange, but
when ponds shrink during the dry
season, lungfish can burrow in the
mud and aestivate (wait in a state
of torpor).
Amphibian
“two lives”
 tetrapods
 respire through skin, lungs







and gills
metamorphosis
Orders Gymnophiona
(apopoda), Anura, Urodela
3 chambered heart
external fertilization &
development
ectothermic
environmental sentinels
Adaptable Amphibians
Orders of Amphibians
 Order Anura- “tail-less one.”
Includes frogs. Exhibit color
patterns that camouflage and
the skin glands secrete
distasteful or poisonous
mucus.
 Order Urodela- “tailed
ones.” Salamanders. Retain
their tails as adults.
 Order Apoda- “legless ones.”
Caecilians which burrow in
the soil.
 All amphibians go through a
complete metamorphosis.
The link from water to land
 As animals evolved, there was a





movement from an all water
habitat to an on land habitat.
However, there had to be a link
between these two.
Amphibians are attached both to
the water and to the land.
They have moist skin through
which gas respires.
They have lungs as adults and gills
as larva.
Their bodies adapted to prevention
of predation and acquisition of
food.
Reptilia
 Dry scaly skin of
keratin
 ectothermic
 3 chambered heart
 amniotic egg
 breathe through lungs
exclusively
 Orders Squamata,
Chelonia, Crocodilia,
Tuatara
Reptile Adaptations
How would you classify this organism?
Reptile Video Quiz
Aves
 Endothermic
 4 chambered heart
 air sacs
 feathers of keratin
protected by oil
 crop & gizzard
 hollow bones
 scales
 amniotic egg
Class Aves
 Common characteristics:
 Light skeleton made of hollow bones;




some organs are also absent to allow for
a lighter body.
The beak is made of keratin, and has
proven to be very adaptable to different
diets during avian evolution.
Birds are endothermic; they use their
own metabolic heat to maintain a warm,
constant body temperature.
Feathers aid in flying and insulation.
Exhibit highly proficient lungs with the
adaptation of air sacs, which function
to use 90% of the oxygen in air
compared to the 10% that we use.
Origin of Birds
 Theropods- a group of
relatively small, bipedal
carnivorous dinosaurs that most
likely gave rise to birds.
 Archaeopteryx- ancient creature
possessing characteristics of
both birds and reptiles.
Bird Adaptations
Modern Birds
 There are 28 orders of birds.
 Ratites, “flat-bottomed,” -
flightless birds including the
ostrich, kiwi, and emu.
 Flying birds have a sternal keel
supporting their large breast
muscles, which provide flight
power.
 Many birds have extensive
courtship and mating behavior.
Mammalia
 Mammary glands for
feeding young
 hair/fur from ketarin
 differentiated teeth
 endothermic with 4
chambered heart
 3 Groups: monotremes,
marsupials, placentals
Monotremes
 The platypuses and the echidnas,
or spiny anteaters, are the only
living mammals that lay eggs.
 They have hair and produce milk,
although not through nipples.
 After hatching, the baby sucks the
milk from the fur of the mother
who has specialized glands that
secret the milk.
 The egg they lay is reptilian in
structure and development.
Marsupials
 Marsupials- born very early in its
development and completes its
embryonic development while
nursing in a maternal pouch.
 This pouch is called the
marsupium.
 The fetus remains in the pouch
until it is large enough to emerge,
but stays with the mother to nurse.
 Include animals such as opossums,
kangaroos, badicoots, and koalas.
Placental mammals
 Also called eutherian mammals,
which complete their embryonic
development within the uterus,
joined to the mother by the
placenta.
 Order Carnivora- includes cats,
dogs, raccoons, skunks, and the
pinnipeds, or seals, sea lions, and
walruses.
 Order Rodentia- includes rodents
and primates. This is the largest
order of mammals.
primates
 Characteristics:
 Most have hands and feet adapted
for grasping, large brains and short
jaws.
 They also have flat nails on their
digits rather than the narrow claws
of other mammals.
 Primates have well-developed
parental care and complex social
behavior.
 Opposable thumb- relatively
mobile and separate from the
fingers in all primates. It is used for
gripping branches and precise
manipulation.
Test your knowledge
1. What are the four characteristics of
vertebrates?
__________, __________, _________,
and __________________.
2. What is the lateral line system?
____________________________
____________________________.
3. What is the function of the swim bladder
found in Osteichthyes?
_______________________________.
True or False:
4. To aestivate is to wait in a state of torpor.
______
5. Amphibians are tied to the water only
through their need to reproduce. _____
6. Birds are ectothermic. _____
7. Monotreams do not have nipples. ____

In groups of 3 or 4, discuss
the following questions:
1. What enabled amphibians to inhabit
the land?
Keep in mind gas exchange,
reproduction, support, and
locomotion.
2. Do you think that Archaeopteryx is a
link between dinosaurs and
birds? Give at least 2 reasons
why or why not.
3. Explain the differentiation of teeth
found in mammals.
Keep in mind carnivore, herbivore,
and omnivore life styles.
References
 Explorations in Shark Diversity:
 PBS Shape of Life:
 Tree of Life Web
 Chordate Notes
 Smithsonian Marine Station Chordates