From the surface, the sea can look like one homogeneous single habitat. In fact, the ocean has a huge diversity of habitats. There are many different types of marine habitats that serve as homes for different types of organisms.
A few examples of marine habitats:
Sometimes scientists talk about habitats in terms of the layer of water that they lie in:
They also talk about how far habitats are from the shore:
Many factors affect what a marine habitat is like. The major abiotic, or non-living factors, that affect marine habitats are:
These factors are affected by three things:
Generally, if you stay at the same depth, as you get further from shore:
But, as you get further from shore, because the distance to the sea floor increases and it makes things darker, it’s harder for plants that live on the sea floor to grow.
Currents are interesting because they can mix up the water. Currents and tides mean that marine habitats are always changing and they often don’t have clear boundaries.
Perhaps the most important type of currents to marine diversity are the ‘upwelling currents’. These bring cooler, nutrient-rich waters to the surface near the coast. This means that not only can the plants get lots of light and carbon dioxide in a fairly warm environment, but they can also get lots of nutrients. Most marine life lives in coastal habitats, because the conditions tend to be more favourable than the open ocean.
There are also many organisms that rely on currents to move them through the water. For instance, plankton are the many different types of very small organisms (animals, algae, bacteria, etc.) that drift along with the current.
Science / Geography | Ages 7-11
Our Ocean Planet is a comprehensive introductory unit on the oceans for primary school. It covers marine topics across both the UK and globally, developing ocean literacy. The twelve lessons are aligned to the Key Stage 2 science and geography programmes of study.