Hydra
Bilateral symmetry ? have a right and left half that are mirror images of each other
Seen in more advanced animals
Cephalization ? have concentration of sensory structures and nerves and brain region
In head area
Type of Gut
Gut ? is a tubular or saclike region in the body in which food is digested, then absorbed into the internal environment
Saclike guts ? have one opening for taking in food and expelling residues
Tubelike (complete) digestive system ? has an opening at two ends called mouth
And anus
Different parts of system have specialized functions such as preparing, digesting
And storing materials
Types of Body Cavities
May be of three types: coelom, pseudocoel, acoelomate
Acoelomate- tissues fill in region between gut and body wall
No coelom
pseudocoel ?body cavity with no peritoneal lining
Example:
Coelom ? area between gut and body wall with unique tissue lining called ___________
Lining encloses organs and helps hold them in place
Advantage: favors increase in size and activity by
Segmentation
repeating series of body units that may or may not be similar to one another
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All are Kingdom Animalia.
Phylum Porifera
Ex.
Body plan
Germ layers:
Symmetry:
Cephalization:
Gut:
Coelom:
Segmentation:
Endoskeleton: skeleton on inside of body
may be composed of spicules, tough fibers or both
Fibers made of spongin which is a protein
Spicules are sharp and made of calcium carbonate or silica
Skeleton reason sponges have been successful
Sessile
Other characteristics: filter feeder
Water flow through sponge functions to:
Ostium
Central cavity - spongocoel
osculum
collar cells ? line central cavity, have flagella that beat to set up current
trap food for sponge, sponges like to eat
Reproduction
May be sexual or asexual
Sexual-produce both eggs and sperm in same sponge
Sperm released into water through osculum
Sperm enter ostia of neighboring sponge
Eggs retained and fertilized in spongocoel
Zygote leaves through osculum= swimming larvae
Larvae swim away
Larvae go to new location, attach to substratum, develop into adult sponge
Asexual-fragmentation
Part breaks away from parent and grows to new sponge
Phylum Cnidaria
Have cnidocytes or stinging cells
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