1 Phylum Hemichordata • Three body regions • Deuterostome • Gill slits • Open circulatory system • Dorsal and ventral nerve cord 2 3 Chordates 4 Phylum Chordata 5 Phylum Chordata • Notochord • Gill slits in pharyngeal pouches • Dorsal hollow nerve cord • Post-anal tail • Deuterostome 6 Notochord • Flexible, rod-like structure. • Extends length of body on dorsal side. • Axis for muscle attachment & support. • Has a sheath of connective tissue. 7 Dorsal Nerve Cord • Tubular. • Anterior end enlarges to form brain. 8 Slits and Pouches • Opening from pharynx to outside. • Can form middle ear cavity, tonsils, Eustachian tube. 9 Tail • Evolved for propulsion in water. • In humans- becomes the coccyx bone at end of spine. 10 Evolutionary Adaptations of Chordates • From filter feeding ancestors to active predators – Mobility – Oxygen capture – Digestion – Circulation – Nervous system 11 Skeletal Changes • Skeleton becomes stronger to work with bigger muscles • Allows more rapid movement 12 Oxygen Capture • Gill slit and muscular pharynx will move more water over gills – More oxygen is extracted from water 13 Circulation • Stronger heart to circulate blood faster 14 Digestion • Digest more food – Muscularized gut – Digestive glands • Liver • Pancreas 15 Nervous System • More complex for better: – Motor control of body to capture food – Sensory detection of the animals environment – Integration centers (brain) 16 Brain With Three Parts Hindbrain Midbrain Forebrain 17 Chordate Subphyla • Phylum Chordata • Subphylum Urochordata • Subphylum Cephalochordata • Subphylum Vertebrata 18 Subphylum Urochordata • Ex: Sea squirts • Gill slits (pharyngeal slits) • Notochord – Only in larva 19 Sea Squirts 20 21 Subphylum Cephalochordata • Ex: Amphioxus • Notochord length of body • Dorsal hollow nerve cord • Gill slits • Segmented muscles 22 Amphioxus 23 Amphioxus 24 The End (sort of) 25 The Vertebrates 26 Subphylum Vertebrata • Vertebrae replace notochord during embryonic development • Largest group of Chordates. Many species. 27 Fig. 48.8 28 Superclass Agnatha • No jaws • No paired appendages • Notochord as adult • Type of fish. 29 Class Chondrichthyes • Cartilage skeleton • Notochord • No opercula • No swim bladder • Type of fish. 30 Class Osteichthyes • Boney fish • Many varieties 31 Tetrapods • Animals with 4 limbs – Amphibians – Reptiles – Birds – Mammals • Evolved from fish 32 Adaptations to live on land • Gills are usually lost • Lungs function • Breathe through skin • Secrete mucus – Prevent dehydration – Aids in respiration 33 Class Amphibia • Land and water • Skin with mucous secretions • No scales, feathers or hair • Heart with 3 chambers • Exothermic 34 Class Reptilia • Scales • Amniotic egg • Exothermic • Three chambered heart – Alligators have 4 • Claws 35 Class Aves • Feathers • No teeth • Scales on legs • Bones with air spaces • Endothermic • Four chambered heart 36 Class Mammalia • Hair • Mammary glands • Sweat glands • Movable eyelids • Three ear bones • Muscular diaphragm • Endothermic • Four chambered heart 37 Now its your turn… • Group Vertebrate projects. 38.