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Chapter 30

Chapter 30 . Section 1: The Chordates. The Chordates. What Is a Chordate ? Members of the phylum Chordata Animal that has at some stage in its life: Dorsal, hollow nerve cord Notochord Pharyngeal pouches Tail that extends beyond anus. What is a Chordate?. Chordate Anatomy. Notochord .

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Chapter 30

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  1. Chapter 30 Section 1: The Chordates

  2. The Chordates • What Is a Chordate? • Members of the phylum Chordata • Animal that has at some stage in its life: • Dorsal, hollow nerve cord • Notochord • Pharyngeal pouches • Tail that extends beyond anus

  3. What is a Chordate? Chordate Anatomy Notochord Muscle segments Hollow nerve cord Anus Tail Mouth Pharyngeal pouches

  4. What Is a Chordate? • The notochord is a long supporting rod that runs through the body just below the nerve cord. Notochord

  5. What Is a Chordate? • Pharyngeal pouches are paired structures in the throat (pharynx) region. Pharyngealpouches

  6. What Is a Chordate? • The tail can contain bone and muscle and is used for swimming by many aquatic species. Tail

  7. What Is a Chordate? • Most Chordates Are Vertebrates • About 96 percent of all chordate species are vertebrates. • Most vertebrates have a vertebral column, or backbone. • In vertebrates, the dorsal, hollow nerve cord is called the spinal cord.

  8. What Is a Chordate? • As a vertebrate embryo develops, the front end of the spinal cord grows into a brain. • The backbone is made of individual segments called vertebrae. • In addition to support, vertebrae enclose and protect the spinal cord.

  9. Phylogeny of Chordates .

  10. Chordate Evolution • Similarities in anatomy and embryological development indicate that vertebrates and nonvertebrate chordates evolved from a common ancestor.

  11. Nonvertebrate Chordates • Nonvertebrate Chordates • Two groups of nonvertebratechordates: • Tunicates • Lancelets • Soft bodies marine organisms

  12. Tunicates • Tunicates • Larval form of filter-feeding tunicates have all of the chordate characteristics Pharynx with gill slits

  13. Tunicates • Adult filter-feeding tunicates have neither a notochord nor a tail.

  14. Nonvertebrate Chordates • Lancelets are small, fishlike creatures that live on the ocean bottom. Segmented muscles

  15. Lancelets • An adult lancelet has a definite head region that contains a mouth. • As water passes through the pharynx, a sticky mucus catches food particles. • The lancelet swallows the mucus into the digestive tract. Mouth

  16. Lancelets • Lancelets use the pharynx for gas exchange. • Lancelets are thin enough to exchange gases through their body surface. • Lancelets have a closed circulatory system and do not have a true heart.

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