Chapter #33- Poriferans + Cnidarians

Invertebrates- 95% of species

animals that lack a backbone

Sponges

sedentary animals from the phylum Porifera

Sponges are suspension feeders that

capture food particles suspended in the water that passes through their body

Choanocytes

flagellated collar cells that generate a water current through the sponge and ingest suspended food

Spongocoel

cavity that water is drawn in through pores

Osculum

opening that water goes out of in a spongocoel

Have a radial body plan

Cnidarians

Gastrovascular cavity

body plan of a cnidarian that is a sac with a central digestive compartment

Two variations on the body plan

sessile polyp (W), motile medusa (M)

Chidocytes

cells that function in defense and capture prey

Nematocysts

specialized organelles within cnidocytes that eject a stinging thread

2 subphyla of Cnidaria

Medusozoa and Anthozoa

3 groups of Medusozoa

hydrozoa, scyphozoa, cubozoa

Portuguese-man-of-war

most well known hydrozoa

Scyphozoans

Jellies exist in the medusa form as the prevalent life cycle form

Cubozoans include

box jellies and sea wasps who can be very toxic and exist in medusa form

How is sea wasps venom deadly

makes cells permeable to potassium ions which can result in cardiovascular collapse

Anthozoa includes

corals and sea anemones, they occur as polyps W