Nitrogenous wastes--
catabolism
anabolism==breakdown
amonia--liquid and toxic, amonotelic
uric acid--crystalline form, uricotelic
urea--liquid, not as toxic as amonia, ureotelic
Osmotic and ionic balance
isotonic, hypertonic, hypotonic
isosmotic, hyperosmotic, hyposmotic
contractile vacuoles,
flame cells
metanephridia
green gland
salt secreting glands