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THE ROCK POOL ADVENTURE (Teachers) These pages are just a guide for you to develop further according to the age(s) of your children) You can use them and/or edit them using a Word-processor) Rockpools are exciting places to explore. Here is a guide to what you might be able to find lurking beneath the surface. When you are out on the seashore, remember that wildlife is all around you. Rockpools and rocky shores support a wealth of marine biodiversity which is accessible to everyone. Here is some more information about a few of the most common species, to start you off on your rockpooling adventure. Remember to follow the seashore code* the guide to careful rockpooling. Common (Green) Shore Crab – Carcinus maenas The Shore Crab is the commonest crab on European coasts and is not restricted to rocky shores, being found on mud and sand as well as in the brackish conditions of saltmarshes and estuaries. The shell, or carapace can be up to 8 cm long and is broader than it is long. Shore crabs can vary in colour from dark green to orange and red. Males usually have five joints to their tail and a broader abdomen, which is folded under their body, whilst females have seven joints and a more pointed abdomen. Crabs, like other crustaceans, grow by moulting and growing a new shell. At moulting time, the shell splits and the animal, in its soft coat, eases itself out. Having left the old suit it swells with water and hides under a stone until its new hard shell has grown. This can take several days. Crabs can also regenerate limbs – if a limb is lost, a new one is formed inside the shell and exposed at the next moult. If one of the front claws is lost (there is one cutting claw and one crushing claw), the claws can swap function – so crabs can be ambidextrous. They often carry a parasitic barnacle Sacculina carcini that can be seen as a smooth orange ball attached to the abdomen. The parasite not only prevents the crab from moulting, but can also turn male crabs into females! Crabs can be found year round on the Devon coast. Common Prawn – Palaemon serratus Prawns have an almost transparent body with brown lines. Blue and yellow markings may also be present and they can grow up to 11 cm long. They have a long, upward-curving toothed rostrum, 2 pairs of legs and five pairs of swimming limbs. The front pair of legs has nippers, which they use to collect food. They can swim either backwards in rapid bursts with their tail fan, or forwards using flaps under the abdomen to propel them. They are often found in pools at the edge of the sea, especially amongst seaweed in August and September on flood tides. The populations move offshore in Winter and return in Spring. Gently disturbing the water often results in them moving quickly in an escape movement. Beadlet Anemone – Actinia equina Beadlet anemones are commonly found on rocky shores in the intertidal zone, being well adapted to high temperature and dessication. They can grow up to 5 cm high and wide and can live for more than 3 years. They have up to 192 tentacles, arranged in 6 circles around the mouth. They are armed with stinging cells, to paralyse their prey, but are also quite aggressive and will use their poison on fellow anemones, to secure a favoured place on the rocks. The stinging cells are located in acrorhagi, or blue bulges, found in a circle below the tentacles. The bulges swell up and fire stinging harpoons into their prey, or the attacking anemone! In water, the tentacles can be seen, but out of water they contract and pull in their tentacles, appearing as a soft brown-red, slimy mass, attached to the rock. Common Limpet – Patella vulgata Limpets are abundant on most rocky shores with the Common Limpet being most frequently found. They are clearly identifiable by their thick conical shell, up to 6 cm long, with coarse ridges radiating from the apex. They are often greyish-white in colour, however individual species are not easily distinguishable. Limpets resist dessication by grinding their shell into the rock, until it is a perfect fit, and clamping down with their strong muscular foot until the tide comes in again. They are territorial and return to the home scar they have created by following the trail of mucus they left as they went foraging whilst the tide was in. They change sex at 4 years, becoming female, and can live up to 17 years where environmental conditions lead to slow growth. They can be found attached to the rocks all year round. Shanny / Common Blenny – Lipophrys pholis The Shanny is one of the most widespread of all British inshore fish. It can grow up to 15 cm long and live for up to 16 years! It has mottled pale brown and green skin, but these colours change depending on the environment it is in, as camouflage. Males become almost black around breeding time. The Shanny is distinguishable from other Blennies by its lack of head tentacle. It is distinguishable from Gobies as it has a continuous dorsal fin, as opposed to separate dorsal fins. It feeds on the legs of barnacles, amongst other things. It is common in rock pools and can survive low salinity and little water, by hiding under moist stones. It is less commonly found in winter as it migrates downshore and lives below the low water mark to weather winter storms. Cushion Star – Asterina gibbosa Cushion stars are up to 5 cm across, with 5 short stubby arms. They can be olive-green, brown or orange in colour. They start out as males and turn into females at about 4 years old. In contrast to other starfish, females can lay up to 1000 orange-coloured eggs in May. These hatch out after 2 – 3 weeks into tiny cushion stars. Unlike other predatory starfish they are scavengers, feeding on micro- organisms, decaying seaweed and dead invertebrates by pushing lobes of the stomach through the mouth and secreting digestive juices. They can regenerate limbs, like other starfish. They are generally found clinging to the underside of stones. Acorn Barnacles – Semibalanus balanoides, Cththamalus montagui, Cththamalus stellatus Acorn Barnacles are very common, being found on all European coasts. They can be found in their millions on rocky shores. They can grow to up to 1 cm in diameter, with a conical shape and a diamond-shaped opening made of 4 plates, two larger than the others, surrounded by 6 large grooved plates. Eggs are brooded inside the adult and released as larvae in the water. These feed on plankton, moult to a simple shelled stage, and settle on a rock, becoming the barnacles we see on the shore. Barnacles feed by extending their limbs into the water, out of the shell opening, and filtering plankton. These are just a few of the amazing creatures and their shells that you will find in your rock pool. DRAW EVERYTHING YOU SEE AND RECORD IT ON YOURR ROCKPOOL CHART – You can look them up when you get back to school. The photos and much of the above information can be found in the book 'Great British Marine Animals', Second Edition; ISBN: 09522831 5 8 and RRP £15.00. Now stocked in the DWT shop. Visit www.marinephoto.co.uk for more information. For more information about marine life and marine surveys visit www.marlin.ac.uk. ON THE NEXT PAGE ARE TWO IDEAS FOR MAKING A TOOL FOR YOUR ROCK POOL SURVEYS MAKING THE GRID The String Grid method: You will need : 4 x 1 metre 2cm dowel – thin string – 4x plastic coated terry clips You place the grid over the Rock Pool and RECORD what you see in each 10cm square – to make it easier to record you can number the squares – Eg: the anemone is in 4,4 – you can then PLOT the results on squared paper when yoo get back to school. OR The Squared Paper method. You will need: A roll of the largest gridded paper you can find When you have found a suitable pool draw the outline of this pool on to the squared paper Look into the pool and PLOT what you see the the appropriate squares Work in groups of three or four. The more groups you have will make a more complete survey of the rockpool life at BOTANY BAY ********* REMEMBER – DON’T POKE YOUR FINGERS OR ANYTHING INTO THE POOLS AS YOU DON’T WANT TO DISTURB ANY OF THE LIFE OR LOSE YOUR FINGERS!!!!! ********* Above all – have fun!!! COPY THIS CODE INTO YOUR WORKSHEET OR NOTEBOOK REMEMBER *The Seashore Code • Respect all sea life. Carefully replace all rocks where you • found them. • Poking or squeezing soft-bodied animals can be harmful to • them. • Always put creatures back in their rockpools instead of • leaving them in buckets. • Only collect empty shells. • Watch where you walk. • Please take your litter home. • Beware of cliffs and incoming tides. These notes were taken from the North Devon VMCA – http://www.devonwildlifetrust.org ROCK POOLS Part of the education ‘pack’ provided free by the BOTANY BAY KIOSK BEACH SITE - www.thebeachkioskatbotanykent..co.uk Other items include “How to Make a Simple Kite to fly on the beach” and “Let’s Survey our Beach – A Line Transect” Notes prepared by Harvey Norton.
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