• Spiralians- grow by adding additional mass to body. most live in water and propel themselves using cilia
• Ecdysozoans- grow by molting

• sponges
• kingdom porifera
• are not bilaterally symmetrical and have no tissues
• have choanocytes(special flagellated cells whose beating drives water through body cavity)
• can reproduce sexually and asexually

Eumetzoa vs. Parazoa

Parazoa lack tissues

Eumetzoa have tissues

• coelomates
• go through ecdysis (molting)
• are segmented animals with an external skeleton and jointed appendages that undergo metamorphosis
• are most sucessful in animal phyla in terms of diversity
• include insects,spiders, crustaceans, centipedes

• roundworms
• go through ecdysis (molting)
• inhabit marine, freshwater, and terresterial environments
• many are parastitic in plants or animals

• are coelomates with horseshoe shaped crown of ciliated tentacles around mouth called a lophophore (used for filter feeding)
• lophophorates are sessile (anchored in place)

Cnidarians:

two body forms-->

Polyps

Medusae

• Cnidarians are marine,body have tissues, though not evolved organs, they are carnivores and capture their prey with tentacles that ring mouth
• Polyps-body opening acts as mouth and anus, most build chitinous calcium carbonate) external or internal skeleton. attach to substance are not free-living
• Medusae- free living and umbrella shaped, tentacles surround mouth. Ex: Jellyfish

Nematocyst

• type of Cnidarian that has a small but powerful "harpoon"
• Each nematocyst has a coiled threadlike tubule that may be barbed, the tubule entwines or spears prey and may deliver a toxin
• to propel harpoon it uses water pressure and tubule everts (turns inside out)
• causes stinging sensation to prey so nematocyst sometimes called "stinging nettle"

Rotifera

• rotifers are bilaterally symmetrical, unsegmented, pseudocoelomates
• they are unlike nematodes and are classified in spiralian Platyzoa
• have complex bodies with three cell layers. gut passes from mouth to anus
• called "wheel animals" because the cilia when beating together resembles movement of wheel