The Coelomates

1. The Coelomates Protostomes Deuterostomes Blastopore  mouth Determinate development Embryo develops via spiral cleavage Blastopore  anus Indeterminate development Embryo develops via radial cleavage

2. Phylum Chaetognatha “hairy jaw” - Arrow Worms • planktonic predators • teeth and chitinous spines • lack vascular, respiratory, excretory systems • thin cuticle

3. Phylum Xenoturbellida “strange bristled ones” • simple body plan • no organs and no vascular, respiratory, excretory, reproductive systems

4. Clade Ambulacraria Phylum Hemichordata Phylum Echinodermata • deuterstomes • three-part coelom (tripartite) • similar larval forms • specialized metanephridia (axial complex)

5. The Echinoderms “spiny skin” • exclusively marine, mainly free-living • endoskeleton of calcareous plates (ossicles) • radial symmetry • water vascular system • tube feet

6. Body Structure Pentamerous symmetry Body differentiated into oral and aboral surfaces

7. Class Asteroidea “sea stars” • flattened star-like form with 5 or more arms radiating from central disc • active carnivores with well developed gut which extends into arms (gastric caeca)

8. Internal Anatomy (pyloric ceca) pyloric and cardiac stomachs polian vesicles

9. Cross Section of Arm (pyloric cecum) may also have pedicellariae

11. Class Ophiuroidea “brittle stars” • long, slender, flexible arms sharply marked off from central disc • ambulacral grooves covered by ossicles • simple sac-like gut (no anus)

13. Class Echinoidea “sea urchins, sand dollars, heart urchins” • plate-like ossicles form rigid, interlocking test • ambulacra modified into ambulacral plates with pores for tube feet

14. ambulacra modified into ambulacral plates with pores for tube feet • extremely extensible tube feet • numerous pedicellariae

15. Feeding Behavior • food rasped from rocks and crushed into fine particles with Aristotle’s lantern • biting mouthparts = 5 large triangular plates, each with a sharp tooth

17. Class Holothuroidea “sea cucumbers” • body elongated along oral-aboral axis • tube feet poorly developed (or absent) • oral tube feet may be modified into feathery tentacles used to capture food • anus opens into a large cloaca, which branches off into 2 sets of internal tubes = respiratory trees

18. Sea Cucumber Body Structure • flexible body wall • ossicles reduced to small plates & spicules • burrow via peristaltic action of body

21. Class Crinoidea “sea lilies, feather stars” The most ancient & most primitive of the echinoderms Suspension feeders - capture particles in mucus secreted by tube feet

22. Echinodermata Development Auricularia (holothuroids) Bipinnaria (asteroids) Echinopluteus (echinoids) Ophiopluteus (ophiuroids) Gastrula Larva Doliolaria (crinoids)

23. Phylum Hemichordata “halfway to chordate” have two of the five chordate characteristics pharyngeal gill slits dorsal, hollow nerve cord lack a notochord, postanal tail, endostyle/thyroid

24. Enteropneusta Acorn Worms • burrow into soft sediments using proboscis • deposit feeders or suspension feeders • may be quite large (up to 2.5 m) trunk collar proboscis

25. Pterobranchia