Presentation on theme: "Molluscs` Role in Nature Annelie Ehlvest Tartu Environmental Education Center www.teec.ee."— Presentation transcript:
Molluscs` Role in Nature Annelie Ehlvest Tartu Environmental Education Center
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
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
How long do they live? Big landsnails: 6 – 10 years The freshwater pearlmussel : 150 years River mussels Unio sp.: 40 – 90 years Anadonta sp.: 30 years Small landsnails and slugs: 1- 2 years The blue mussel Mytilus edulis: 10 years
What do landsnails eat? Different parts of flowering plants: leaves flowers fruits underground storage organs
What else do landsnails eat? mushrooms – both mycelium and fruiting body alga lichens ferns mosses
What else do landsnails eat? carrions: copse snail Arianta arbustorum can eat also dead snails the largest European land snail black keel back slug Limax cinereo-niger may attac otherones then in captivety no real carnivorous snails in our country
What else do landsnails eat? muldering plants, also dead wood (can decompose cellulose and partly ligneous) carton and paper (cellulose!)
What do watersnails eat? alga flowering plants dead plants and animals frog-spawn
What bivalves eat? bivalves filter small organic parts from water: phytoplankton zooplankton detritus, floating organic material
glochidial larval stages of uniocean mussels Unio sp. live for some weeks on host fishes gills and skin, eating their tissues freshwater pearlmussel Margaritifera margaritifera does the same for several months What else do bivalves eat?
Who eat landsnails? Several beetles: carrion beetle Phosphuga atrata (1) carabids (2) fireflies, both larva and adults eat only snails (3) juv.
true bugs, Heteroptera brown centipedes, Lithobius forficatus red bugs some fly larva develop in the snails eggs, also eating jung snails Who else eat landsnails?
Lot of birds: thrushes small songbirds hens and ducks
Who else eat landsnails? toads and other amphibians mole hedgehog shrew northern birch mouse jellow-necked mouse rat
squirrel stoat fox mink badger wild boar Who else eat landsnails?
mould on snaileggs green-banded broodsac- a parasitic flatworm (or "helminth") that uses landsnails as an intermediate host Who else are interested of landsnails? EGGS
Who eat molluscs in river, lake and pond? fishes: roach, crucian carp, tench, eel ec mammals: muskrat,otter, mink
Who eat molluscs in the Baltic Sea? fishes: sea- scorpion, flounder, god, turbot, viviparous blenny common starfish chinese mitten crab
Who else eat molluscs in the water? waterbirds: eider steller's eider merganser mallard swan
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
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)
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