| A | B |
|---|
| oral surface | where the mouth is |
| aboral surface | the opposite side of the mouth |
| polyp | cnidarian that has a sac-like attached state (sessile) |
| medusa | cnidarian that has a bill-like stage |
| mesoglea | large, thick, jelly-like portion of the cnidarian |
| cnidocil | short trigger at the narrow edge of the chidocyte |
| namatocysts | stinging cells that contain poison arrows connected to threads |
| cnidocytes | stinging cells found on the cnidarians' tentacles |
| ectoderm | external cell layer |
| endoderm | internal cell later that lines the gut |
| zooplankton | drifting microscopic animals |
| phytoplankton | drifting microscopic plants |
| gastrovascular cavity | a digestive chamber with one opening |
| nerve net | a loosely organized network of nerve cells that allow cnidarians to detect stimuli |
| statocysts | groups of sensory cells that help determine the direction other organisms |
| ocelli | eyespots made of cells that detect light |
| hydrostatic skeleton | layers of muscles that enable the cnidarian to move |
| jet propulsion | method by which medusas move |
| basal disc | the adhesive foot of a hydra |
| septa | thin partitions of anthozoans that provide extra surface area used for digestion of larger prey |
