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

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

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

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

6. Body differentiated into oral and aboral surfaces
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. pyloric and cardiac stomachs
Internal Anatomy
(pyloric ceca)
pyloric and cardiac stomachs
polian vesicles

9. may also have pedicellariae
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 plate-like ossicles form rigid, interlocking test
“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. biting mouthparts = 5 large triangular plates, each with a sharp tooth
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 body elongated along oral-aboral axis
“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 The most ancient & most primitive of the echinoderms
“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 have two of the five chordate characteristics
“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