Rocky reefs are very complex habitats, creating a three-dimensional canvas on which all kinds of life can thrive. Depending upon the depth and energy (strength of waves/water currents) the seabed is exposed to, different communities are able to grow and survive. In shallower, higher energy areas thick algal beds grow including kelp forests, red algae turfs and bryozoans (colonies of tiny creatures). Animals such as corals, sponges, anemones and pink sea fans, dominate in deeper waters and on reefs characterised by boulders. Many rare species thrive along Dorset’s coast including: the trumpet anemone ( Aiptasia mutabilis ), the ross coral ( Pentapora foliacea ), the cup coral ( Caryophyllia inornatea ), the sea fan anemone ( Amphianthus dohrnii ) and pink sea fans ( Eunicella verrucosa ).

Meanwhile in Studland Bay and in the Fleet lagoon large, dense seagrass beds provide shelter, food and protection for a wide range of fish and shellfish species. The fleet is also home to a wide variety of overwintering and breeding birds including the little tern and wigeon. Just south west, off of Swanage bay are extensive Maerl beds. The individual Maerl thalli (individual plant like structures) grow incredibly slowly (0.1cm per year) and due to their irregular shape create a seabed with lots of interstitial space for other fish and invertebrates to hide. To the south of the Isle of Portland, large beds of mussels have formed a biogenic (created by animals) habitat that provides many species such as brittle stars, urchins, dog whelks and spider crabs with a reliable food source.