Phylum Chordata

1. Phylum Chordata Subphyla Invertebrata & Vertebrata from sea otters to sea squirts

2. 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.

3. 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

4. Subphylum Urochordata: • Tunicates & sea squirts • sessile, marine filter feeders w/ tadpole like larvae (comp, embryology) Anatomy of a Tunicate

5. Subphylum Cephalochordata • Lacelets, Amphioxus • notocord persists through adulthood

6. 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

7. 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

8. Agnatha- “jawless fishes” • Lampreys and hagfishes • Lack jaws and have permanently open rasping mouths • scavengers & predators of osteichythyes • unpaired fins • cartilaginous skeleton some

9. 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

11. 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

12. 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.

14. 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. • 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 Ray-finned fishes Lobe-finned fishes

15. 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,

16. 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).

17. 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

18. 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.

19. 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.

20. Reptilia • Dry scaly skin of keratin • ectothermic • 3 chambered heart • amniotic egg • breathe through lungs exclusively • Orders Squamata, Chelonia, Crocodilia, Tuatara Reptile Adaptations

21. How would you classify this organism? Reptile Video Quiz

22. Aves • Endothermic • 4 chambered heart • air sacs • feathers of keratin protected by oil • crop & gizzard • hollow bones • scales • amniotic egg

23. 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.

24. 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

25. 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.

26. Mammalia • Mammary glands for feeding young • hair/fur from ketarin • differentiated teeth • endothermic with 4 chambered heart • 3 Groups: monotremes, marsupials, placentals

27. 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.

28. 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.

29. 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.

30. 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.

31. 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. Test your knowledge

32. References • Explorations in Shark Diversity: • PBS Shape of Life: • Tree of Life Web • Chordate Notes • Smithsonian Marine Station Chordates