Tides are a powerful force of nature, created by the Moon's gravitational pull.
Along the world's coastlines, tides have a profound affect on marine life, creating opportunities for both predators and prey.
Intertidal coastal habitat:
Exposed to the air at low tide
Underwater at high tide
As the tide recedes, hidden ecosystems are revealed. This is the intertidal or littoral zone.
In Northern Australia, low tide reveals damp sand and mud, packed with microscopic life.
This is an opportunity for bubbler crabs to rise from their burrows and sift the sand for a meal.
But while some come out at low tide, others must hide.
In Alaska as low tide approaches, clams bury themselves underground for protection against grizzly bears.
Rocky shores don't offer such protection.
Low tide in western Canada, and these mussels and barnacles are fully exposed to the hot Sun. They must wait for high tide's protection, while nearby raccoons hunt crab.
In New Zealand, rock arches create gentle tides, where stingrays gather to rest and breed.
In Patagonia, southern sea lion pups use tidal pools to learn how to swim.
But high tide brings orca, or killer whales lurking in the waves.
The intertidal zone is an ever-changing environment, challenging predators and prey to adapt to survive in these diverse but ruthless ocean habitats.