Beneath the waters of Chichester Harbour there are slippers, spiders and peacocks (limpets, crabs and worms), dahlias, carrots and gooseberries (anemones, sponges and sea squirts)!
Underwater, the Harbour is crowded with life. Pontoon pilings and mooring chains are covered in a wealth of colourful seaweeds and animals, and reefs of native oysters provide a home for bright red sea squirts, hydroids and sponges. The worms, crustaceans and molluscs that provide food for Harbour birds also sustain a rich food chain below the waves. The shallow waters teem with plankton and are an important nursery area for young fish.
The mud of the Harbour floor is quite inhospitable, but pebbles and shells provide a hard surface for marine plants and animals to anchor to. There is a very unusual plant that manages to survive in the mud. Eelgrass (Zostera) is not seaweed, but a flowering plant. The patches, or 'beds', are unique in Sussex, and significant nationally, and provide a sheltered nursery for juvenile fish, crabs and other species.
In the muddy seabed, most life is anchored in, burrowed in or crawling around within the sediment. Worms do well here; including the Peacock worms that hide their bodies in tubes made from mud and mucus. Sea squirts are living sieves that form encrusting colonies on pebbles and cobbles, sucking water in, filtering the edible bits and ejecting the water. In shallower areas you will find sponges growing on boulders. Apart from minute single-celled organisms (like amoebas), sponges are the simplest members of the animal kingdom.
Dahlia, Daisy and Snakelocks anemones are common throughout the Harbour. All anemones have stinging cells for defence and capturing prey. They are carnivorous, feeding on small marine animals such as shrimp, prawns and even small fish.
Slipper limpets were accidentally introduced in the late 19th Century, and completely alter the seabed habitat, providing hard surfaces to plants and animals to attach to.
Alien-looking cuttlefish are abundant in the summer months, hunting and nesting among the weeds and eelgrass.
Crabs, like the Spider, Hermit and Shore crabs, are like armour-wearing underwater insects. The Hermit crab does not have it's own armour, so it borrows discarded mollusc shells instead. As the crab grows it needs to find a new home and will carry out a thorough inspection before moving in.
The sheltered Harbour supports large and diverse populations of fish (over 40 species altogether). Several commercial species use the Harbour as a nursery area, including Bass, Bream, Mullet, Sole and Plaice. You can also find colourful Corkwing wrasse. Pipefish are found among algal cover in sheltered areas, and like their close relatives the Seahorse, it is the male who gives birth to the young.
The Harbour also has its share of large predators, including Harbour Seals, and Smoothounds, which belong to the Hound Shark family.
Subtidal Video (YouTube)
Great British Marine Animals by Paul Naylor
Sussex Marine Life by Robert Irving