chapter 34 phylum hemichordata- acorn worms
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Chapter 34 Phylum Hemichordata- Acorn Worms. Have three body regions: proboscis, collar, and trunk Have both a ventral and dorsal nerve cord anterior portion of dorsal is hollow Have pharyngeal gill slits Have ciliated larvae identical to echinoderms Have a hydrostatic skeleton - PowerPoint PPT PresentationTRANSCRIPT
Chapter 34 Phylum Hemichordata- Acorn Worms
• Have three body regions: proboscis, collar, and trunk
• Have both a ventral and dorsal nerve cord anterior portion of dorsal is hollow
• Have pharyngeal gill slits
• Have ciliated larvae identical to echinoderms
• Have a hydrostatic skeleton
• Filter-feeders using their pharyngeal slits
Hemichordata
Hemichordata
Hemichordata
Hemichordata
Hemichordata
Chapter 34 Vertebrate Evolution and Diversity
Characteristics of Chordata
1. Notochord
2. Dorsal hollow nerve cord
3. Pharyngeal Slits
4. Muscular Postanal Tail
Notochord: This is a longitudinal, flexible rod of cartilage that is located between the gut and the dorsal nerve cord. The notochord can last into adulthood, but in most cases it is replaced by the vertebral column. The spongy material in between the vertebral bones is all that is left of the notochord.
Notochord
Dorsal, Hollow Nerve Cord: This is a tube that is formed from a plate of ectoderm that is rolled up into a tube. It is located dorsal to the notochord, it lies above the gut and beneath a single, hollow nerve cord. Due to its hollow structure the dorsal nerve cord is considered very unique. It will develop into the chordate's central nervous system.
Pharyngeal Gill Slits: These structures are openings of the upper digestive tube. During the embryonic stage these slits connect the outside to the pharynx. Early chordates used them to filter feeding. Over time the slits became modified to function in gas exchange.
Anus Tail
Muscular Post anal Tail: Most chordates have a tail extending beyond the anus. In many aquatic species the tail is equipped with skeletal and muscular tissue for movement.
Subphylum Urochordata
Subphylum Urochordata-sea squirtstunicates; cellulose in outer covering
Subphylum Urochordata
Subphylum Urochordata
Subphylum Urochordata
Subphylum Subphylum CephalochordataCephalochordata lanceletslancelets
Subphylum Cephalochordata lancelets
• Most like early chordates (but chordates did not descend from them)
• Marine filter feeders
• Feeble swimmers
• Muscles segments develop from blocks of mesoderm called somites that are arranged around each side of the notochord.
Subphylum Cephalochordata lancelets
Subphylum Cephalochordata lancelets
Subphylum Subphylum Cephalochordata Cephalochordata lanceletslancelets
Fossils of early Fossils of early vertebratesvertebrates
Subphylum Vertebrata
• Notochord develops into a cartilaginous or boney vertebral column that surrounds and protects the spinal cord
• Have a cranium or skull that surrounds and protects the brain
• Have a advanced closed circulatory system
• Cephalization increases dramatically
Embryonic formation of the neural crest
Class Myxini-Jawless fish-Hagfish-All marine No limbs or appendages; Cartilaginous skeleton; no vertebrae
Class Myxini-Jawless fish-Hagfish
Class Myxini-Jawless fish-Hagfish
Class Myxini-Jawless fish-Hagfish
Class Myxini-Jawless fish-
Hagfish
Class Cephalaspidomorphi-lamprey-Jawless fish; Cartilaginous skeleton; No limbs or appendages; notochord has dorsal extensions that partially enclose the nerve cord “vertebrae”
Class Cephalaspidomorphi-lamprey
Class Cephalaspidomorphi-
lamprey
Class Cephalaspidomorphi-lamprey
Class Cephalaspidomorphi-lamprey
Class Cephalaspidomorphi-lamprey
Evolution of the Vertebrate Jaw
Ostracoderms- armored but no jaws; some were active and had paired fins
Ostracoderms
Placoderms-first jaws
• Skeletal rods called gill arches of the most anterior pharyngeal gill slits became the jaw
Placoderms
Placoderms
Chondricthyes sharks and rays• Completely cartilaginous skeleton;• Strong powerful swimmers• Must swim constantly to produce water flow over gills
due to no operculum • Lateral line system that
detects sound waves• Oviparous• Ovoviviparous• Viviparous• Cloaca
Chondricthyes sharks and rays
Chondricthyes sharks and rays
Chondricthyes sharks and rays
Osteichthyes-bony fish• Operculum-bony covering over gill arches pulls
water into mouth and over the gills
• Swim bladder- gives buoyancy regulates level in water; evolved from crude lungs
• Bony fish evolved in freshwater first and developed crude lungs to supplement gills for gas exchange; then when they returned to salt water, the opening to the lungs closed and they evolved into swim bladders
• Two chambered heart
Ray-finned fishes
Ray-finned fishes
Ray-finned fishes
Lobed-finned fishes
Lobed-finned or lobed finnedfishes; Coelacanths
Lobed-finned fishes
Lobed-finned fishes
Lobed-finned fishes
Osteichthyes-bony fish
Osteichthyes-bony fish
Amphibians
• Three chambered heart-
• External fertilization
• Embryo and larvae forms must have water
• Epidermis is permeable to water
• No claws on toes
Amphibians
Amphibians-salamander
Amphibians-tree frog
Young tadpole
Tadpole to frog
Amniote egg
Reptiles
• Amniote egg-
• Scales composed of keratin-also protein in hair and feathers
• Three chambered with partial septum in ventricle
• Internal fertilization-
• Modern reptiles are ectotherms but many dinosaurs were endotherms
Reptiles
Care of eggs and young
Reptiles
ReptilesReptiles
Reptiles
Reptiles
Reptiles
Reptiles
Reptiles
Aves-birds
• Evolved from dinosaurs (reptiles)
• Modifications for flight-
• Internal fertilization with amniote egg
• Four-chambered heart
• Elastic air sacs connected to lungs for increased respiration and dissipation of heat
Archaeopteryx
Archaeopteryx
Flightless dinosaur with protofeathers
Caudipteryx flightless but with true feathers
Aves
Aves-Birds
Aves-Birds
Mammalian Characteristics
• Hair- composed of keratin
• Endothermic
• Mammary glands
• Four-chambered heart
• Diaphragm
• Internal fertilization
• Differentiated teeth
Monotremes
Monotremes
Monotremes
Monotremes-echidnas
MonotremesMonotremes-echidnas
Monotremes-echidnas
Monotremes-echidnas
Marsupials
Marsupials
Marsupials
Marsupials
Prosimians-lemurs
HominoidHominid
Primates
New world monkeys Old world monkeys prehensile tail lack prehensile tail nostrils open to the sides nostrils open downward all arboreal some ground dwelling
Apes-Hominoids Not hominidsGibbon Orangutan
Gorilla
Chimpanzee
Apes-Bonobo
Hominids-bipedal-upright stance
Lucy-Australopithecus
afarensis early hominid
Turkana boy1.7 million years old
between homo habilis and homo
erectus