A sea habitat is a body of salt water, its coastline and floor, all of which are inhabited by multiple species of marine life. A sea habitat has several zones that serve as homes to different types of creatures. There are the shallow, coastal zones along the sea's border with land, deeper areas past the edge of the continental shelf, and the floor of the sea itself. Sea habitats are affected by factors such as temperature, tides, current, salinity, depth and vegetation.
The wildlife of a sea habitat can be quite diverse, because the creatures that live there have adapted to the varying conditions of the ocean. While the majority of creatures breathe through gills and cannot survive outside of water for long periods, some have adapted to living next to tidal areas where they occasionally might find themselves temporarily stranded on land or in pools of water with high salt concentrations. Other creatures generate their own light, which they use to navigate in the darkness of deep waters. Some, such as sharks, have even developed electroreception that gives them the ability to navigate and find food by sensing electrical impulses.
The temperature of a sea habitat affects how marine animals adapt to it. Even slight variations in temperature can have a profound impact on the inhabitants. To maintain proper body temperature, most cold-blooded marine animals must consume large amounts of food so they can stay active and keep their body temperature slightly above that of the water. In very cold waters, marine mammals such as whales and walruses have developed a thick layer of fat just under the surface of their skin to help them maintain their body temperature.
A sea habitat is also affected by current. Current, whether from the wind, tides or global movement, distributes food, soil and even eggs throughout the habitat. Large, underlying global currents affect the temperature of a sea habitat. Currents can also affect the migratory habits of marine life in the sea.
Light is another factor that is important to a sea habitat and the animals that live in it. Light is vital for photosynthesis in seaweed. The ability of light to penetrate the water is affected by factors including depth, waves, foam, plankton and particles in the water. Runoff, either natural or man-made, can have a severe effect on light’s ability to penetrate deep enough to allow photosynthesis by marine plants.
The sea floor is another important part of a sea habitat. The sea floor, or substrate, can consist of many types of rock and particles. These rocks and particles help determine what kind of marine animals and vegetation can survive on the substrate. For instance, seaweed cannot survive on a sandy substrate, because it needs solid rock as an anchor.