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