Why is the intertidal zone so harsh?

Answer 1

The intertidal zone is a difficult place to live because you get flooded once or twice a day and then left high and dry.

Also, the tidal zone is exactly where waves beat on the shore. Even the calmest places will be raked by storm waves. Winter storms can actually grind floating ice against the rocks and strip them clean of shellfish and seaweed.

The creatures that live here must be able to survive in salt water, in fresh water (rain), and in dry air. Part of the day they're protected by a layer of water, then they're exposed to burning sun and heat, or freezing cold, snow and ice. And, of course, the oxygen levels in air and water are very different.

In the meantime, whether they're plants or animals, they must manage to make a living, sometimes in water, sometimes in air. And in the dry and in the wet, try not to get eaten.

Answer 2

Creatures have to adapt tp harsh conditions that are constantly changing

winter makes pools icy; Summer makes water hot, oxygen evaporates.

water can be too salty or not salty enough.