Phyla Hemicordata and Chordata

BIO 2215 Oklahoma City Community College Dennis Anderson

1

2

Phylum Hemichordata • Three body regions – Proboscis – Collar – Trunk • Deuterostome • Gill slits • Open circulatory system • Dorsal and ventral nerve cord 3

4

5

Chordates 6

Phylum Chordata 7

Phylum Chordata • Notochord • Gill slits or pharyngeal pouches • Dorsal hollow nerve cord • Postanal tail • Segmented muscles • Deuterostome 8

9

10

11

12

Evolutionary Adaptations of Chordates • From filter feeding ancestors to active predators – Mobility – Oxygen capture – Digestion – Circulation – Nervous system 13

Skeletal Changes • Skeleton becomes stronger to work with bigger muscles • Allows more rapid movement 14

Oxygen Capture • Gill slit and muscular pharynx will move more water over gills – More oxygen is extracted from water 15

Circulation • Stronger heart to circulate blood faster 16

Digestion • Digest more food – Muscularized gut – Digestive glands • Liver • Pancreas 17

Nervous System • More complex for better – Motor control of body to capture food – Sensory detection of the animals environment – Integration centers (brain) 18

Brain With Three Parts Hindbrain Midbrain Forebrain 19

Chordate Subphyla

Phylum.

Chordata

Subphylum.

Urochordata

Subphylum.

Cephalochordata

Subphylum.

Vertebrata 20

Sea Squirts 21

Subphylum Urochordata • Sea squirts • Gill slits (pharyngeal slits) • Notochord – Only in larva • Adult has tunic 22

23

24

25

Amphioxus

26

Subphylum Cephalochordata •

Amphioxus

• Notochord length of body • Dorsal hollow nerve cord • Gill slits • Segmented muscles 27

Amphioxus

28

The End

29