The Shore Thing Project

The Shore Thing Project www.marlin.ac.uk/shore_thing

ROCKY SHORE ECOLOGY

Tides • Tides are caused by the gravitational pull of the moon and sun • There are generally two tidal cycles in 24 hrs • The rise and fall of the tide varies depending on whether it is a neap or spring tide • Tidal range varies around the UK coast.

The Rocky Shore Environment • All species specially adapted • Marine and terrestrial • Exposure high • Changing conditions • Different zones on the shore • Location important for identification

Environmental Variations Feeding time Exposure Light Temperature variation Salinity variation Upper shore Desiccation Lower shore

‘Splash’ Zone • Extremely exposed • Salt spray • Conditions extremely variable • Dominated by lichens • Rarely submerged

Upper shore • Very exposed • Conditions very variable • Diversity low dominated by channelled wrack and small periwinkles • Submerged for short periods • Exposed for long periods

Middle shore • Moderately exposed • Conditions moderately variable • Dominated by fucoids, barnacles, molluscs and gastropods • Species depends on exposure • Submerged and exposed every tide

Lower Shore • Less exposed • Conditions relatively stable • High diversity of specially adapted marine species • Dominated by kelps, red algae, sea squirts and sponges • Submerged most of the time, only exposed on low spring tides

Rocky Shore Identification Major groups/phylum of species are: • Algae (seaweeds) • Lichens • Marine Invertebrates (animals without backbones) • Porifera (sponges) • Cnidaria (anemones/jellyfish/hydroids) • Crustacea (crabs/barnacles) • Mollusca (top shells/limpets) • Echinoderms (sea urchins/starfish) • Marine Chordates (animals with backbones) • Tunicates (sea squirts) • Fish

Marine Algae • Brown – Wracks and Kelps • Green • Red – includes encrusting algae • Flowering plants such as seagrass

Lichens • Fungus and algae living together in symbiosis • Often an encrusting layer on rocks • Found in the splash zone

Marine Invertebrates (animals without backbones) • Porifera - Sponges • Attached to surfaces • Very simple animals, covered with pores • Rounded or branched forms • Often need microscope to identify them

Cnidaria - Anemones, corals, hydroids and jellyfish • ‘Mouth’ surrounded by tentacles • Attached and free swimming forms • Sometimes forming large colonies

Crustacea - Crabs, lobsters, shrimps etc. • Segmented body covered in hard plates • Divided into three segments • Jointed limbs • Adapted to live in every marine environment

Mollusca - Snails, bivalves, chitons, limpets, sea slugs etc. • Largest most diverse group • Gastropods have large muscular foot • Bivalves body surrounded by two shells held together with a hinge

Echinoderms - Starfish, sea urchins, sea cucumbers and brittlestars • Tube-feet, internal skeleton of bony plates • Often external skeletons

Marine Chordates (animals with backbones) • Tunicates – Star of ascidian and sea squirts • Larval stage has a backbone • Two openings body covered in ‘tunic’ of jelly • Colonies sometimes confused with sponges

Fish – Shanny, blenny, rockling, clingfish etc. • Divided into two main groups, elasmobranchs (sharks, rays etc) and teleosts (bony fish) • Elasmobranchs have a skeleton of cartilage • Teleosts skeleton is bony

Key Features 1 2 3 4

Species No. 1 Cone shaped shell, up to 2.5 cm high Tooth on inside of mouth opening Shell grey-green Shiny ‘mother of pearl’ inside shell opening H Osilinus lineatus

Species No. 2 Bushy brown seaweed Covered in what looks like small leaves and tiny round floats Very dense, feels coarse and wiry May form long lengths (like a washing line) D Sargassum muticum

Species No. 3 Prominent midrib Pairs of almost spherical gas bladders Dark olive brown Up to 1 m long F Fucus Vesiculosus

Species No. 4 Small round hole on underside of the shell Dull greenish in colour with reddish-purple broad diagonal stripes Small top shell 1.6 cm high. 2.2 cm across C Gibbula umbilicalis

The Shore Thing Project