LECTURE 5 BIODIVERSITY OF ON AND IN SEDIMENTARY SHORES

Slide no. 1 Title Slide. 2 Introductory. See manual pages 15-17, 19, 25 et seq. 3 Organisms that can be seen at the surface. 4 Mussels Mytilus edulis (, ) tend not to form large colonies on substrata that are less permanent than solid rock. 5 Close-up of mussel with associates caught up in its byssus. 6 A cockle Cerastoderma edule (Mollusca, bivalvia) half buried in fne sand. 7 Cockle: feeding/respiration currents. 8 Often all that is visible is dead remains. 9 Shell of blunt gaper Mya truncata (Mollusca, bivalvia). 10 Shell of razor clam Ensis arcuatus (Mollusca, bivalvia). 11 trails. 12 Trail of common periwinkle Littorina littorea (Mollusca, gastropoda). 13 Flat periwinkles making trails in sand Littorina obtusata & L. mariae (Mollusca, gastropoda). 14-16 Trail of a small whelk ?????? (Mollusca, gastropoda). 17-21 Trail leading to buried Philine aperta (Mollusca, gastropoda). 22 Burrowing bivalve, the tellin Angulus tenuis (Mollusca, bivalvia), a siphon feeder that 'hoovers' particles on the sand surface from below. 23 Introductory. 24 A variety of surface signs of animals beneath. 25 Concentration of lugworm anal casts and respiration vents. 26-28 How to dig for a lugworm. 29 Freshly dug lugworm Arenicola marina . Chaetae clearly visible. 30 How to dig for the sea potato. 31 Sea potato ventilation vent, open at surface. 32 Sand section with sea potato in situ . Respiration shaft marked with arrow. Very long tube feet maintain this shaft. Anal spines and tube feet form a cavity for faeces and tube feet at front facilitate feeding and slow forward burrowing by loosening the thixotropic sand. Manual p. 16. 33 Sea potato or heart urchin Echinocardium cordatum . 34 Sea potato burrowing. 35-36 Surface tufts of expertly constructed sand-grain tubes of sand mason worm. 37 Sand mason worm tube, excavated (mostly), worm having escaped by almost instantaneous burrowing, gripping sides of tube interior with numerous minute 38-39 Plaice Pleuronectes platessa on sand surface and burrowed. 40 Masked crab Coristes cassivelaunus (dead), a burrowing crab with long, hairy antennae with which it maintains contact with surface water and oxygen supply. 41 Lists of genera found in particulate shores. 42 The thin tellin Angulus tenuis (syn. Tellina tenuis ) is a particle feeder, the longer of its two siphons emerging, when under water, to 'hoover' food from the sand surface.

43 Three more common molluscs found buried in sand: the elliptical trough shell Spisula elliptica , banded venus fasciata and a small example of the comon cockle Cerastoderma edule . 44 A petri dish containing a few examples of the smaller sand-dwelling animals, identified and sorted for counting: worms Nephtys caeca and Phyllodoce maculata , and the amphipod crustacean Bathyporeia elegans . 45 Close-up of a watch glass containing the above two worms. 46 Nephtys caeca freshly removed from sand by digging. 47 Phyllodoce maculata on the surface, making use of a thin post-tide water film, left by the retreating tide. On this occasion there were thousands of Phyllodoce on the surface. 48-50 Three examples of minute crustaceans extracted from sand by sieving. 48 A cumacean, Diastylis rugosa . 49 The shrimp Crangon crangon . 50 In patches or zones, a very numerous amphipod Bathyporeia elegans . 51 A list of animal phyla and genera found in water film in the pores between sand grains, the interstitial meiofauna. Manual p. 25. 52 Finale.