Intertidal Zones
The Intertidal Zones, also known as the littoral zone, is the area between the marks left by the high-tide and the low-tide. Many people think it as the place where land, water, and air meets. It is alternately covered by water and exposed to air during each tidal cycle. This area is very rich in nutrients and oxygen, and it is the home of many types of animals. The picture below shows a clearer explanation of what the Intertidal Zone is.
A Tough Environment
The intertidal zone is pretty much inhabitable. It is washed by the tides everyday, so the organisms there must adapt to large changes daily. The moisture, temperature and salinity largely change everyday, so we can easily assume that organisms there do not have an easy life.
The moisture changes at high tide and low tide. During high tides, the land is covered in water, and so organisms must be able to live underwater. During low tides, the land is dry, and organisms there must be able to survive dryness as well.
The temperature's change is also large everyday. The temperature is cool to cold during high tides, yet can vary from freezing to very hot during low tides.
The salinity of the area changes from time to time, depending on the weather. During hot days, the sun evaporates the water so quickly that the salt that stays down, makes the beach very salty. However during rainy days, the water washes away all the salt and the beach is almost salt less. During conditions when the beach is too salty or not salty enough, some organisms can be in serious danger.
Low tides sometimes form tide pools, places where they remain wet,but they don't last very long. The salinity of tide pools can be as salty as the salinity of ocean waters to much less salty. Organisms must adapt to these changes also. Some organisms, such as sculpin and blennies, live in tide pools. The movie below is basically a summary for all the writing above (suggested to people who hates reading):). Ignore the beginning, it is somewhat random, but the reste is pretty cool.
The Spray Zone, also known as the Upper Littoral, the Supralittoral Fringe, the Splash Zone, or the Barnacle Belt, is most of the time a dry area, but is sprayed with ocean or salty waters during high tides. But it can also be flooded during storms and spring tides. Organisms that live in this area include the barnacles, isopods, lichens, lice, limpets, periwinkles, and whelks. Animals who live here are mostly land animals that can survive with some salt water.
The high tide zone, also known as the Upper Mid-littoral Zone and the high intertidal zone, is an area only flooded during high tides (probably where its name comes from). Organisms living in this area includes anemones, barnacles, brittle stars, chitons, crabs, green algae, isopods, limpets, mussels, sea stars, snails, whelks and some marine plants.
Middle Tide & Low Tide Zone
The middle tide zone, also known as the Lower Mid-littoral Zone, is an turbulent area that gets covered and uncovered twice a day with ocean water. Organisms living there include anemones, barnacles, chitons, crabs, green algae, isopods, limpets, mussels, sea lettuce, sea palms, sea stars snails, sponges and whelks.
The Low tide Zone also known as, Lower Littoral Zone, is always underwater, except during low tides. Organisms in this area are not as adapted to huge changes as the organisms in the zones above it. Organisms around the area includes abalone, anemones, brown seaweed, chitons, crabs, green algae, hydroids, isopods, limpets, mussels, nudibranchs, sculpin, sea cucumber, sea lettuce, sea palms, sea stars, sea urchins, shrimp, snails, sponges, surf grass, tube worms, and whelks.
Notice that as we go nearer to the water, more types of organisms exists there. This is because water is an essential element to all living things.
Predators
Organisms living at intertidal zones not only have to adapt to the dangerous changes everyday, but they also need to take shelter from predators. When it is high tide, they are mostly preyed by fish. When it is low tide, their fear turns toward land animals and humans.