Chapter 33

The Ancestors Protists: Choanoflagellates

The Ancestors Colonies of choanoflagellates

The Ancestors Colonies of choanoflagellates

Porifera – The Sponges

Sessile filter feeder Grouped based on “skeleton” type. Can form gemmules for protection.

Porifera – The Sponges Asymmetrical No tissue layers.

Porifera – The Sponges Sexual reproduction - hermaphrodites Can grow whole new sponges if cut in pieces

Cnidaria Examples: jellyfish, anemones, hydra and coral

Cnidaria Named for cnidocytes

Cnidaria Diploblastic Two body forms: polyp & medusa Grouped based on amount of life spent as polyp or medusa

Cnidaria Reproduces asexually by budding.

Cnidaria

Platyhelminthes - Flatworms Examples: planaria, liver flukes, tapeworms

Platyhelminthes - Flatworms Most are parasitic

Platyhelminthes - Flatworms Bilateral symmetry Simplest phylum with a head Simple organ systems Reproduce sexually and asexually

Platyhelminthes - Flatworms Acoelomates Triploblastic

Rotifera Named for feeding rotors Pseudocoelomates Have an anus! Images from

Rotifera Usually reproduces by parthenogenesis

Nematoda – Roundworms Found in most aquatic habitats, soil, and in plant and animal tissues

Nematoda – Roundworms Many are parasitic – hookworms, roundworms, pin worms, heartworms, etc.

Nematoda – Roundworms Pseudocoelomates Simple organs

Annelida – Segmented Worms Examples: earthworms, fireworms, leeches

Annelida – Segmented Worms “Little rings” –repeating segments, some specialized Coelomates Setae Parapodia

Annelida – Segmented Worms Fairly complex anatomy

Mollusca Largest classes: Gastropods Bivalves Cephalopods

Mollusca Muscular foot

Mollusca Head

Mollusca Visceral mass

Arthropoda “Jointed foot”

Arthropoda Most successful animal phyla – 67% of all species!

Arthropoda Four main groups: Cheliceriforms Myriapods Hexapods Crustaceans

Arthropoda Exoskeleton - ecdysis

Arthropoda Open circulatory system

Arthropoda Tracheal tubes Spiracles vs. book lungs

Arthropoda Malpighian tubules

Echinodermata “Spiny skin”

Echinodermata Radial symmetry

Echinodermata Water vascular system Tube feet

Echinodermata No head or brain Simple anatomy Deuterostomes Endoskeleton