20 Items: Having a diet consisting of other animals. • The ability of cnidarians to regrow lost body parts. • Stinging organelles within cnidocytes, injecting toxins into prey. • The union of egg and sperm outside the body, common in many cnidarians. • Symmetry around a central point, a characteristic feature of cnidarians. • ...

30 Items: a place to dispose of waste\ • When fertile land becomes a desert • loss of resources though soil erosion • a species that is non native to an area • radioactive waste from nuclear reactors • travel and appreciation of nature areas • power obtained by harnessing of the wind • The uncontrolled expansion of urban areas • the decrease in the ph levels in the ocean • ...