The Shore Thing Project
www.marlin.ac.uk/shore_thing
ROCKY SHORE
ECOLOGY
Tides
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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
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All species specially adapted
Marine and terrestrial
Exposure high
Changing conditions
Different zones on the shore
Location important for
identification
Environmental Variations
Upper shore
Lower shore
‘Splash’ Zone
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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
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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)
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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
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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
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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
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Cone shaped shell, up to 2.5 cm high
Bushy brown seaweed
Tooth on inside of mouth opening
Covered in what looks like small
leaves and tiny round floats
Shell grey-green
Very dense, feels coarse and wiry
Shiny ‘mother of pearl’ inside shell
opening
May form long lengths (like a washing
line)
Prominent midrib
Large round hole on underside of the
shell
Pairs of almost spherical gas
bladders
Dark olive brown
Up to 1 m long
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Dull greenish in colour with reddishpurple broad diagonal stripes
Small top shell 1.6 am high. 2.2 cm
across
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Species No. 1
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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
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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