What is the pelagic zone?

The open water column away from the ocean floor and coastlines The ocean floor and the water immediately above it Coastal waters within 12 miles of shore The top 10 meters of any ocean water

What are coral reefs made of?

The calcium carbonate skeletons secreted by tiny animals called coral polyps Compressed layers of ocean sediment and sand Rocky underwater cliffs eroded by waves Colonies of algae that harden over time

What symbiotic relationship makes tropical coral reefs possible?

Coral polyps host photosynthetic algae called zooxanthellae that provide the coral with nutrients Corals filter-feed on bacteria and get all energy from ocean currents Corals produce their own food through chemosynthesis Corals rely entirely on dead organic matter falling from above

Why are coral reefs called the 'rainforests of the sea'?

They cover less than 1% of the ocean but support about 25% of all marine species They produce the same amount of oxygen as tropical rainforests They are found in tropical regions, just like rainforests They have similar weather patterns to rainforests because of high rainfall

What do kelp forests have in common with tropical coral reefs?

Both are highly biodiverse habitats that provide structure and shelter for a wide variety of marine species Both are found in warm tropical water only Both are built by animals secreting calcium carbonate Both require the same water temperature and clarity to survive

In which ocean zone does most photosynthesis occur?

The sunlit (epipelagic) zone, from the surface to about 200 meters The abyssal plain, where most nutrients accumulate Hydrothermal vent zones, where chemicals fuel growth The midnight zone, where the pressure is highest

Sea otters play a 'keystone species' role in kelp forests by:

Controlling sea urchin populations, which prevents urchins from overgrazing and destroying kelp Producing nutrients that fertilize kelp growth through their waste Competing with fish for food, which benefits kelp Maintaining water temperature to keep kelp warm

Where do most coral reefs form, and why?

In warm, clear, shallow tropical waters between 30°N and 30°S latitude, where sunlight is abundant In cold polar water where nutrient levels are highest In deep ocean trenches where they are protected from storms Equally throughout all ocean depths and regions

What is the Great Barrier Reef and why is it significant?

The world's largest coral reef system, stretching over 2,300 km along Australia's northeast coast A large underwater mountain range in the Pacific Ocean A deep ocean trench near Australia The world's largest kelp forest, found off southern Australia

What is the Sargasso Sea, and what makes it unique?

A region of the North Atlantic defined by ocean currents, not land boundaries, famous for floating Sargassum seaweed A tropical sea between Africa and South America with no significant life A name for the deep water area above the Mariana Trench The shallowest sea in the world, located in the Mediterranean