Learn about marine environments
Marine Ecology Systems
Shallow Waters & Reefs
Shellfish & Crustaceans
Squid, Octopus, and Other Primitive Animals
Fish Part A Cartilaginous Fish
Fish Part B Bony Fish:
Turtles, Sea Snakes and Seabirds
Human Impact on Marine Environments & Fishing
Learn about Different Marine Environments and the things that Live there
This course helps you to an understanding of all sorts of different marine environments. Starting with shore lines; we discover how the edge of the sea supports a very diverse range of organisms. Shorelines can vary a lot too; from rocky shores to sandy beaches and tidal estuaries with and abundance of mangrove plants.
As the water deepens there are rocky and coral reefs, intertidal zones, shallow channels, deep oceans and more.
Consider the Diversity of a Rocky Shore
Rocky shores are found where the sea meets the land. A rocky shore is where the main substrata is rock. It is also where, at high tide, the shore is covered by the sea and pounding waves. At low tide this inter-tidal zone is exposed to air and the heat of the sun. The animals in this area must be capable of living in both air and water. During the dry periods they must withstand the loss of almost 70% of their body water. They must cope with freshwater rain when exposed and salty water when submerged.
There are several distinct habitats in rocky shores:
These are formed when waves, wind and rain carve rock into flat platforms. One rock platform can support many different kinds of plants and animals, because some sections are almost always under water, while other parts are usually dry.
These are usually formed when a boulder lodges in a depression in the rock and grinds a hollow as it rolls around in the waves. The depression eventually becomes deep enough to hold water during low tide. These pools provide a useful habitat for some creatures and is especially important for those creatures which must live submersed in water.
Groups of boulders are found where little wave action occurs, and the shore is relatively flat. Creatures live on a around these boulders where shade may provide small microclimates or small crevices may trap water. As well as supporting lots of unusual plants and animals, rocky shores are important fish nurseries and roosting and feeding grounds for birds.
Some species which live on rocky shores like to shelter by rocky shores, in areas where stands of seaweeds break the waves' power. Rocky shores also provide lots of food for fish.
Algal beds of this habitat are an important food source for rare and threatened species like marine turtles. At low tide, wading birds love to feed on crabs and limpets on exposed rocks.
Rocky Shore Inhabitants
There are lots of different things that can be found living on rock shores, including:
Mobile Animals (Motile)
These are mobile and move up and down with the tide. They include crabs, starfish, sea-lice, sea snails, octopus and small fish. They are usually well camouflaged for self-preservation, or brightly coloured to scare off predators. Most, such as crabs and snails, have an external shell for protection from the elements.
Fixed or Sedentary Animals (Sessile)
These are confined to one location and can be specifically adapted to that niche site. Some are confined to the high shore, while others are confined to the low tidal zone. They are usually firmly attached to rocks so that sea waves cannot wash them off. They are normally protected by strong shells which can seal up during dry periods or low tides. Eg. rock oysters, mussels, barnacles.
These organisms are made up of a fungus and a microscopic algae living together in a symbiotic relationship. They live at the top of the shore where the tide doesn’t rise.
Most plants found on rocky shores are seaweeds. Instead of roots, they have special suckers called ‘holdfasts’ which cling to rock, even in big waves. Not all seaweeds have long, floaty fronds. The fronds can be tiny, so the seaweed looks like velvet covering the rocks. Other may look like tiny cabbage leaves.
Many rocks are covered with microscopic plants, many of which are diatoms, tiny, single-celled plants with hard silica shells. These plants are the main food for many grazing animals.
Snails and limpets
Many species of these animals live on rocky shores. They eat microscopic plants, lichen or seaweed. Limpets are snails, which have a cup-shaped shell. They use a large, flat foot to tightly clamp the rock.
Barnacles attach themselves permanently to one spot on the rocky shore. Using specialised organs, they catch food as it floats by in the waves.
Also known as cunjevoi. They are filter feeders and also remain in one permanent place. They pump large amounts of water through their bodies while under water, and then filter the food out. They are also an important food source for other animals.
An anemone is a single animal with a sack-like body and tentacles around a single opening. Some are capable of moving about very slowly. In rock pools and on reefs just off shore, there are many species of anemone.