Cnidarians

Cnidarians phylum

Cnidaria

what animals

corals, sea anemones, Jelly fish

where do they grow

mostly on tropical islands in saltwater and freshwater lakes & streams

what sizes

ranges from tiny animals no bigger than a pinhead to giants w/ tentacles several meters long

what are they called

often called Ctenophora, or Coelenterata

what do they eat

All carnivorous

nick name

flowers of the animal kingdom

digestive tract

saclike digestive tract

Body structure

ectoderm, endoderm, mesoglea

Ectoderm

outer layer, has cells that aid in capturing food and secrete mucus

Endoderm

has cells that produce the digestive enzymes and break up food particles

mesoglea

the jelly like material between the ectoderm and endoderm

gastrovascular cavity

central cavity and often called coelenteron

Two main forms of Cnidarians

polyp and medusa

Polyp body shape

hollow cylinder or bag that opens/closes at the top

polyp characteristics

tentacles form a ring around a small mouth at the top, mouth leads to a central body cavity, sessile

polyp mesoglea

very thin

examples of polyps

corals, sea anemones

medusa body shape

like umbrella

medusa characteristics

mouth and tentacles hanging down, mouth leads upward into gastrovascular cavity, motile

medusa mesoglea

thick

examples of medusa

jellyfish, man of war

Body symmetry of cnidarians

radial symmetry

what parts for food capture

cnidocytes and nematocysts

cnidocytes

stinging cells

nematocysts

long, coiled, tubular harpoon like structure found in each cnidocyte cell

high body resistance leads to

survive sting

low body resistance leads to

deadly/allergic reaction

why do people pee on sting

because venom is made of protein, destroyed by another protein: urine has high protein content or urea