Dive deep with aquatic wildlife trivia on whales, dolphins, sharks, octopuses, coral reefs, and the bizarre creatures of the deep sea. From echolocating giants to eight-armed escape artists and glowing life in the midnight zone, the ocean hides the planet's strangest wonders. Take the plunge and see if your marine knowledge can handle the pressure.

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These tiny marine animals with tentacles are the primary builders of coral reefs, secreting calcium carbonate to form hard skeletons.
This is the scientific study of cephalopods such as squid, octopus, and cuttlefish.
This massive filter-feeder holds the record as the largest fish in the ocean, reaching lengths of up to 40 feet.
This massive marine mammal holds the title as the largest animal to ever exist on Earth.
This colorful single-celled algae lives inside coral tissue, providing up to 90% of the coral's energy through photosynthesis.
Squid, octopus, and nautilus all belong to this class of mollusks, named for the "feet" on their heads.
Unlike bony fish, sharks and rays have skeletons made entirely of this flexible tissue.
Unlike fish, whales and dolphins breathe air through this opening on top of their heads.