Holy CRAP a Giant Stingray. Photograph courtesy Zeb Hogan - Fish experts believe the giant stingray, such as this one in Cambodias Mekong River, is the largest freshwater species on Earth. This specimen measured more than 13 feet meters) long.
Sea Butterfly (Limacina helicina) by sierraclub: This lentil-size Arctic snail has a translucent shell & wings evolved from its foot to keep it afloat as it drifts along the ocean currents & to trap plankton.
Atolla is a deep sea jelly fish which can be up to across and looks more like a flower than an animal. When touched or disturbed it produces bright, rapidly-flashing circles of blue bioluminescent light that scientists think may confuse would-be hunters.