I work on plants and animals that live in the intertidal, so I like this question. Most of the organisms that live in the intertidal are more comfortable in the water than out of it, since they have evolve from marine ancestors. So at, many of them feed during high tide when they are covered by water. I study mussels, which feed underwater by pumping water through their body. They strain tiny singled celled plants and bacteria out of the water for food. There is actually plenty of food in the water for them, its just so small you and I cannot see it without a microscope. We call the tiny animals those that mussels eat for food plankton, and we call the way mussels eat filter-feeding .

Another intertidal animal, whelk (a kind of snail), eats mussels. It drills a tiny hole in the mussel shell with tiny sharp teeth. After it makes the hole it can eat the mussels insides by slurping it up like a straw. There a wide number of ways that intertidal animals eat, and plenty of things in the water for food. As for temperature, the intertidal animals here around UCSB live in water that ranges from about 50-66 Fahrenheit. They are very tolerant of a wide range of temperatures, especially since they can get very hot and cold at low tide, when they are out of the water. If the water gets too hot or cold, the animals and plants in the intertidal can die or stop growing and breeding. You might notice that in El Nino years , the large kelp stands off the coast die off. This is from the very warm waters that occur during El Nino. I study how intertidal animals respond to heat. When they get too hot, some of the important chemicals in their body start to break down. The animals then start to make repair chemicals, called heat shock proteins to fix the damage. This helps them to withstand hot conditions. We can produce the same chemicals to repair damage in our own bodies.