Life underwater: The seabed

Depending on the depth, the seabed harbours certain types of flora and fauna.

Rocky seabeds

A rocky seabed is a firm foundation for protecting life and providing something for it to cling to, and is teeming with life.

Whether the waters are calm or turbulent, dark or light, every living creature has a place where it can live. In fact, it is because of the strength of the foundations that fixed life forms (sea anemones, sponges, etc.) as well as moving animals can proliferate: some find refuge in the rocks while others feed on the fixed organisms.

The different types of rock formation explains why there is such extraordinary diversity in the forms of life.

Fields and seagrass

Underwater seagrass is composed of vast fields of aquatic plants that withstand the pounding of the waves and current, but do not stand up so well against pollution and other forms of human intervention.

Underwater fields are an essential part of the ecosystem, providing a home and a source of food for many species.

Their long and flexible leaves decrease the force of the waves, and so prevent coastal erosion. They also provide a shelter in which many living creatures can reproduce (crabs, sea urchins, starfish as well as numerous molluscs and shellfish). Every autumn, the dead leaves accumulate on the beaches preventing the sand from being blown away during the winter storms.

The destruction of the seagrass must therefore be considered a major threat to the environment.

Sandy seabeds

At first glance, one would think that there is no life at all on flat and monotonous sandy seabeds... and yet! Even if the animal and plant life is not flourishing, some surprising species have adapted in various ways to this particular environment.

The animal life stays hidden and camouflaged, making it difficult to observe. Rays, soles, crabs, and plenty of others, have all learnt to blend in with their surroundings that are constantly in movement as the seabed is swept by the ebb and flow of the waves.

The open ocean

We rarely dive in the open ocean for comfort and safety reasons, and because the lack of markers is extremely disorientating.

Tossed around by the currents, another set of life forms develops in these dark blue surroundings. Invertebrates (strangely shaped plankton, jellyfish, squid...) avoid being spotted because they are transparent. Here you will also find ocean fish, sunfish, sea bass, mullet, tuna, sea bream…

Far from the coast, the deep blue is also the kingdom of giants: dolphins, whales, sharks…

Coral reefs

Coral reefs are found in all intertropical areas. Three following conditions must be present in order for them to develop: water temperature over 20°C, lots of light and clear water. Because of the many brightly coloured fish that live in these waters, there is an ever-changing spectacle for the diver. It is also, without doubt, the most delicately balanced environment of them all. Even weak levels of pollution, temperatures that are too high by just one or two degrees for more than one week or currents that are too strong for more than a few days have a negative impact on the corals.