Diploblastic - Animals that exhibit both ectoderm and endoderm in the embryo
(Corals, jellyfish)
Triploblastic - Animals that have intervening Mesoderm layer (bilaterians)
Bilaterians - All Multicellular animals other than sponges and cnidarians
Exhibit bilateral symmetry and cephalization
Cephalization - Organization of senses and locomotion toward head region
, Larva - Sexually immature and anatomically distinct from the adult, undergoes
metamorphosis
Juvenile - Resembles an adult, but not sexually mature
Cambrian explosion - 535-525 million years ago, marks earliest fossil appearance of
many animal major groups
Hox Genes - Control the development of body form (Hox Gene "__" can tell to form an
arm)
Protosome - Cell proliferation by spiral cleavage
Coelom forms within the middle tissue germ layer
Initial opening of gut becomes the mouth
Deuterostome - Cell proliferation by radial cleavage
Coelom forms from outpocket of the middle tissue germ layer
Initial opening of gut becomes the anus
Coelom - Body cavity surrounding the gut
Sessile - Do not exhibit locomotion
(Sponges)
Collar Cells - Flagella bearing cells that create water currents that move through the
body of the sponge
Spicules - Tiny calcium/silica structures
Sponges (Phylum:Porifera) - Hermaphrodites (release sperm into environment)
Jellyfish, Anemones, Corals
(Phylum: Cnidaria) - Have radial symmetry
Possess two specialized cell layers (tissues) and nerve cells
Two Body Forms: Sessile polyp and free swimming medusa
Nematocysts - Held under pressure (140 atmospheres) These are the microscopic
venomous spines on the tentacle
Lophotrochozoa - Animals that share horse-shoe shaped feeding structure called a
lophophore and a Ciliated larva called trocophore
Flatworms (Phylum: Platyhelminthes) - Lack circulatory, respiratory, and skeletal
systems
Coelom is absent and gut incomplete
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