Transcript Phylum Chordata - Biology Junction

Phylum Chordata
•Charactertistics of Chordates
•All chordates possess a notochord.
•Long felxable rod between gut & nerve cord
•Runs most of length of animal
•Possess a dorsal, hollow, nerve cord
•Possess pharangeal slits
•Muscular post-anal tail
Urochordates
• Subphylum Urochordata
• Commonly called
turnicates
• Sessile marine animals
as adults - Motile as larva
• Larva possess a clear
notochord which is less
evident in adults
• Filter feed through use of
siphon
Subphylum Cephalochordata
• Commonly known as
lancets
• Have all features of
the ideal chordate
• Bury selves in sand,
and filter-feed through
mouth
Phylum Chordata: The
Vertebrates
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Subphylum Vertebrata
Seven extant classes
First 3 commonly called fishes
Remaining 4 called tetrapods (4 feet)
All possess some form of segmented
vertebra
Class Agnatha
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Commonly known as Jawless Fish
Include hagfish & Lampreys
Lack paired appendages
Lack bony skeleton
Lack jaws
– Usually have circular sucking mouthparts
• Lampreys parasitize other fish
Lampreys
Hagfish
Class Chondrichthyes
• Include sharks & skates, & rays
• Very successful class
• Called cartilagenous fishes because skeleton is
cartilage not bone
• Approx. 750 species
• Have paired appendages
• Many have acute senses
• Sharks have a lateral-line system
• Allows shark to detect water pressure changes
Sharks
Noteworthy Shark Species
Great White Shark
Tiger Shark
Whale Shark
Bull Shark
Rays & Skates
Southern Stingray
Manta Ray
Skates
Class Osteichthes
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Called Bony fish
Most diverse of all fish
Have skeleton made of bone
Have Cycloid Scales
Have paired fins
Allowed evolution of 4 limbed amphibians (tetrapods)
Possess scales for protection
Have bony flap called operculum
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Allows water to be drawn over gills by fins
Have Swim bladder
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Gas content can be manipulated allowing for changes in bouyancy
Bluefish
Class Amphibia
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First vertebrates to inhabit land
Most are 4 limbed (tetrapods)
Include frogs, salamanders & caecilians
Have 3 chambered heart
Have more complicated gas exchange
organs (often a combination of lungs, gills
and skin)
Order Urodela
(Salamanders & Newts)
• Urodela ("tailed ones" - Salamanders)
• More dependent on water
• Many species possess gills as adults
Class Apoda
("tail-less ones" - Frogs & toads)
• Have more developed
lungs than salamanders
– Lack a diaphragm & must
“swallow” air
• Most diverse and
common of amphibians.
• Toads are the first
amphibians to evolve
keratinized skin.
– This waterproofs the skin
preventing water loss
• Toads must still return to
water to lay eggs.
Common North American Frogs
North American Toad
Green Frog
Bullfrog
Poison Arrow Frog
Leopard Frog
Peepers
Caecilia ("legless ones")
Reproduction
• Lack internal
fertilization & amniotic
eggs
• Reproduction must occur
in H2O
• Most species undergo
metamorphosis
– Larval stage (tadpole) is
usually an aquatic
herbavore
– Lacks legs, respiration is
through gills
– Develops into tetrapod
adult (usually carnivorous)
Class Reptilia
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Includes lizards, snakes, turtles, and crocodilians
Over 7000 species
Possess several advanced features over amphibians
Most adaptations towards independence from H2O
Possess scales containing keratin
Keratin is a waterproofing protein which prevents water
loss in an organism
• Possess an amniotic egg.
– Prevents water loss of embryo. Allows for eggs to be laid on dry
land
• Combined with internal fertilization, allows reptiles to
reproduce independently of water
• Reptiles are "cold blooded" or ectotherms
– Cannot internally regulate body temperatures
– Reptiles can regulate body temperatures behaviorally (eg.
Basking or swimming)
– Nutritional requirements are lower than warm blooded animals
The Amniotic Egg
Modern Reptiles
• Order Chelonia (Turtles
& Tortoises)
– Inhabit aquatic and
terrestrial environment.
– Are herbavores,
carnivores, and omnivores
– Characterized by
possessing a hard dorsal
shell
– Made from bone,
extensions of backbone
and rib cage
Common North American Turtles
Order Squamata
• Order Squamata (Lizards & Snakes)
• Most numerous & diverse of the reptiles
• Most relatively small Although monitors
and their relatives can grow to 6' in length
• Herbivores, carnivores & omnivores
• Most able to exhibit some form of
hibernation
Noteworthy Lizards
Eastern Fence Lizard
Leopard Gecko
Komodo Dragon
Anole
North American Snakes
Order Crocodilia
(Crocodiles, Alligators, & Caimans)
• Largest extant reptiles can grow to over 15’ and weigh over a
ton
• Primarily aquatic they are true reptiles
• Inhabit warm, tropical climates
• Order most closely related to the dinosaurs
Crocodilians
Crocodile
Caiman
Alligator
Gavail
Class Aves
(The Birds)
• Evolved from dinosaurs during
Mezozoic era.
• Aminotic eggs and scales on
legs reminants of reptilian
origins
• Almost all adaptations of these
animals are made for flight.
• Presence of feathers
– Made of keratin
– Can be used for insulation and
flight
• Forelimbs developed into
wings
• Honeycombed, light bone
structure
Feathers
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Beak Types
Absence of some organs
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Females usually have 1 ovary
Absence of teeth lighten head
Replaced by gizzard in abdomen & beak
Beak made of keratin
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Proven very adaptable structure, having a variety of shapes for differing diets
Reproduction
•Reproduction is through hardened amniotic eggs
•Since birds are endothermic, these must be kept warm by
parents
•This behavior called brooding
Birds Feet
Modern Birds
• Over 8600 species & 20
orders of birds
• Classified into 2 general
groups
• Flightless species
including ostrich, emus, &
kiwis are known as
ratites
• Lack sternal keel on
breastbone
• Lack strong breast
muscles needed for flight
Ostrich: A ratite
Modern birds contd.
• Other species capable of
supporting flight called
carinates
• 60% are "perching birds"
called passeriforms
• Possess a sternal keel
on breastbone
• Support strong breast
muscles required for flight
The sparrow: A passeriform carinate
Class mammalia
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Approx. 4500 species of mammals
Evolved from mammal-like reptiles called therapsids in the triassic
period
Diversified greatly following the extinction of dinosaurs
Mammilian Characteristics
– Have Hair
• Made of keratin
• Aids in maintaining body temperature
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Endothermic
– Maintain body temperature internally
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Have efficient respiratory system including a diaphragm
Efficient circulatory system with a 4-chambered heart
Most possess placentas and give birth to live young
Have mammary glands to produce milk for offspring
All show parental care of offspring
Have largest brains of all vertebrates
Have differentiated teeth
– Unlike earlier vertebrates, several different teeth can exist in mammal jaws
– Eg. The molars & incisors in the human jaw
General Types of Mammals
• Monotremes
– Early branch from
reptilian line
– Include platypuses &
echidnas (spiny
anteaters)
– Only group to lay eggs
(reptilian in structure)
– Have mammary
glands to feed young
Duck Billed Platypus
Echidna
Marsupials
• Include opossums, kangaroos & koalas
• Mostly found in Australia & New Zealand
– Were isolated in these landmasses when the
continents separated and did not evolve li the same
way placental mammals did
• Do not develop placentas
• Give birth to young very early
• Fetuses complete development in pouch called
marsupium
• Mammary glands found in pouch nourish young
until development is complete
Examples of marsupials
Koala
Opossum
Kangaroo
Placental Mammals
• Complete embryonic development in uterus
• Joined to parent by organ called placenta
– Only "disposable" mammal organ
– Discarded following birth
– Exchanges gasses, nutrients & waste between mother and fetus
Common North American Mammals 1
Common North American Mammals 2