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

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

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

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

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

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

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)

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

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

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)

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

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

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

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

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

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

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

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

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

Pterobranchia