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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
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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 • 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 • 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
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
Noteworthy Shark Species Great White Shark Tiger Shark Whale Shark Bull Shark
Rays & Skates Southern Stingray Manta Ray Skates
Class Osteichthes • 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 • Allows water to be drawn over gills by fins • Have Swim bladder • Gas content can be manipulated allowing for changes in bouyancy
Class Amphibia • 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
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 • 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
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
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 Komodo Dragon Eastern Fence Lizard Anole Leopard Gecko
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 Alligator Gavail Caiman
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
Beak Types • Absence of some organs • Females usually have 1 ovary • Absence of teeth lighten head • Replaced by gizzard in abdomen & beak • Beak made of keratin • 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
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 • 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 • Endothermic • Maintain body temperature internally • 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