Molluscs` Role in Nature

1. Molluscs` Role inNature Annelie Ehlvest Tartu Environmental Education Center www.teec.ee

2. How many different molluscs live in Estonia? On the land: about 80 species of snails In freshwater: about 40 species of snails and 20 species of bivalves In the Baltic around Estonia 8 species of bivalves and 20 species of snails

3. “Molluscdiversity” on land and in freshwater in neighbourhood: In Finland: 128 species of snails and 30 species of bivalves In Latvia: 129 species of snails and 30 species of bivalves In Sweden: 437 species of snails (110 of these are landsnails and slugs) and 32 species of bivalves

4. How long do they live? The freshwater pearlmussel: 150 years River mussels Unio sp.: 40 – 90 years Anadonta sp.: 30 years The blue mussel Mytilus edulis: 10 years Small landsnails and slugs: 1- 2 years Big landsnails: 6 – 10 years

5. What do landsnails eat? Different parts of flowering plants: • leaves • flowers • fruits • underground storage organs

6. What else do landsnails eat? • mushrooms – both mycelium and fruiting body • alga • lichens • ferns • mosses

7. What else do landsnails eat? • carrions: copse snail Arianta arbustorum can eat also dead snails • the largest European land snail black keel back slugLimax cinereo-niger may attac otherones then in captivety • no real carnivorous snails in our country

8. What else do landsnails eat? • muldering plants, also dead wood (can decompose cellulose and partly ligneous) • carton and paper (cellulose!)

9. What do watersnails eat? • alga • flowering plants • dead plants and animals • frog-spawn

10. What bivalves eat? bivalves filter small organic parts from water: • phytoplankton • zooplankton • detritus, floating organic material

11. What else do bivalves eat? • glochidial larval stages of uniocean musselsUnio sp. live for some weeks on host fishesgills and skin, eating their tissues • freshwater pearlmussel Margaritifera margaritifera does the same for several months

12. Who eat landsnails? Several beetles: • carrion beetle Phosphuga atrata(1) • carabids (2) • fireflies, both larva and adults eat only snails (3) 2 1 3 ♂ juv.

13. Who else eat landsnails? • true bugs,Heteroptera • brown centipedes,Lithobius forficatus • red bugs • some fly larva develop in the snails eggs, also eating jung snails

14. Who else eat landsnails? Lot of birds: • thrushes • small songbirds • hens and ducks

15. Who else eat landsnails? • toads and other amphibians • mole • hedgehog • shrew • northern birch mouse • jellow-necked mouse • rat

16. Who else eat landsnails? • squirrel • stoat • fox • mink • badger • wild boar

17. EGGS Who else are interested of landsnails? • mould on snaileggs • green-banded broodsac- a parasitic flatworm (or "helminth") that uses landsnails as an intermediate host

18. Who eat molluscs in river, lake and pond? • fishes: roach, crucian carp, tench, eel ec • mammals: muskrat,otter, mink

19. Who eat molluscs in the Baltic Sea? • fishes: sea-scorpion, flounder, god, turbot, viviparous blenny • common starfish • chinese mitten crab

20. Who else eat molluscs in the water? • waterbirds: • eider • steller's eider • merganser • mallard • swan

21. Molluscs role on land? • Food for many animals • Consumers of plants and mushrooms • Sorse of calcium for birds, especially in nesting time • Decomposers of dead plants • Intermediate hosts for parasitic flatworms

22. Molluscs role in fresh water? • Food for many animals • Consumers of plants • Filtering plancton and detritus • Parasites on fishes • Intermediate hosts for parasitic flatworms • Part of plancton in larva stage (zebra mussel) • Empty shells are bildingmaterial for caddisflies(Limnephilus flavicornis)

23. Molluscs role in Baltic Sea? • Food for many animals • Consumers of plants • Filtering plancton and detritus, cleaning water • Empty shells are used by hermit crabs as “homes”

24. Text: Anneli Ehlvest Pictures: Epp Margna Photos: Anneli Ehlvest, Tarmo Niitla