{"id":20396,"date":"2025-05-13T17:11:09","date_gmt":"2025-05-13T15:11:09","guid":{"rendered":"https:\/\/asleman.org\/?page_id=20396"},"modified":"2025-10-03T12:47:57","modified_gmt":"2025-10-03T10:47:57","slug":"mollusques","status":"publish","type":"page","link":"https:\/\/asleman.org\/en\/mollusques\/","title":{"rendered":"Molluscs"},"content":{"rendered":"
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Molluscs<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Here you will find information on the molluscs that can be seen in Lake Geneva.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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Photo: Marc Bernard<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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species present in Lake Geneva<\/div>\t\t\t
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quagga mussels in Lake Geneva (estimated 2024)<\/div>\t\t\t
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The molluscs of Lake Geneva<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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You can find out more about the molluscs of Lake Geneva in issue 113<\/a> of our quarterly magazine Lake Geneva region<\/a> as well as in our themed leaflets<\/a>our infographics<\/a> or in our weekly column News in 60 seconds<\/a>numbers 77<\/a>, 78<\/a> and 88<\/a>.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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Introduction <\/div><\/span>\n\t\t\t\t\t\t\t\n\t\t\t<\/path><\/svg><\/span>\n\t\t\t<\/path><\/svg><\/span>\n\t\t<\/span>\n\n\t\t\t\t\t\t<\/summary>\n\t\t\t\t
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Molluscs, whose name comes from the Latin Mollis<\/em> (soft), represent one of the phyla containing the most species. Two classes are represented in Lake Geneva: bivalves and gastropods. Initially, the body of a mollusc was divided into three parts: the head, the foot and the visceral mass. The head contains the sensory organs and the mouth. The mouth contains a sort of raspy tongue with tiny teeth for grazing. Over the course of evolution, the \"head\" of bivalves gradually disappeared. The foot is a muscle used for movement. Here too, in bivalves, the foot atrophied slightly as the species became more sedentary. Finally, the visceral mass contains the viscera. These are protected by the mantle, which is the origin of the shell.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/details>\n\t\t\t\t\t\t

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General <\/div><\/span>\n\t\t\t\t\t\t\t\n\t\t\t<\/path><\/svg><\/span>\n\t\t\t<\/path><\/svg><\/span>\n\t\t<\/span>\n\n\t\t\t\t\t\t<\/summary>\n\t\t\t\t
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Bivalves<\/strong><\/h4>

Uniquely aquatic, bivalves are commonly referred to as shellfish. Sheltered by their two shells, joined by a ligament, they feed by filtering water through their siphons. In this way, they capture micro-particles of food and plankton, as well as minerals and metals contained in the water. In Lake Geneva, the proliferation of the Quagga mussel (an invasive exotic species) may partly explain the crystalline appearance of the water. This intense filtration could eventually pose problems for other organisms in Lake Geneva that feed by filtering the water. Because of their ability to filter water, bivalves are good indicators of pollution. Heavy metals, phytosanitary products and other plastics are stored and accumulated inside the organism.<\/p>

Gastropods<\/strong><\/h4>

Gastropods are characterised by their shell, if they have one, which is typically twisted. Most species are hermaphroditic. Found both on land and in water, gastropods can be found practically everywhere. Some aquatic gastropods, such as snails, breathe through a pulmonary system. These species must therefore regularly go to the surface to collect oxygen. Herbivores, Lake Geneva gastropods feed on aquatic plants and algae.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/details>\n\t\t\t\t\t\t

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Watch out for invaders! <\/div><\/span>\n\t\t\t\t\t\t\t\n\t\t\t<\/path><\/svg><\/span>\n\t\t\t<\/path><\/svg><\/span>\n\t\t<\/span>\n\n\t\t\t\t\t\t<\/summary>\n\t\t\t\t
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Molluscs can very easily colonise new bodies of water as a result of human activity. The hypotheses of arrival of the various invasive species range from the ballast tanks of boats (for quagga and zebra mussels) to aquariums (Hydrobia of the Antipodes). It is therefore vital to protect Lake Geneva and other lakes by cleaning and drying your boat thoroughly before moving to another body of water. If you wish to dispose of an aquarium, it is advisable to take its contents to a pet shop.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/details>\n\t\t\t\t\t\t

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Emblematic species of Lake Geneva <\/div><\/span>\n\t\t\t\t\t\t\t\n\t\t\t<\/path><\/svg><\/span>\n\t\t\t<\/path><\/svg><\/span>\n\t\t<\/span>\n\n\t\t\t\t\t\t<\/summary>\n\t\t\t\t
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All the species presented below are in our book of identification cards (sold in our shop<\/a>)\u00a0<\/strong><\/p>

Gastropod<\/strong><\/h4>

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River chub <\/strong>(Ancylus fluviatilis)\u00a0<\/strong><\/em><\/h5>

The River Chickweed has a conical shell reminiscent of a yellow to dark brown Chinese hat.
This mollusc is highly sensitive to pollution, making it a good indicator of water quality.<\/p>

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Ringworm sp. <\/strong>(Lymnaeidae)<\/em><\/h5>

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Snails have a clearly visible spiral shell with the last turn being wide, paunchy and lighter in colour.
They are the hosts of Trichobilharzia sp.<\/em>a bird parasite whose larvae cause itchy skin and infections in humans (duck fleas).<\/p>

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Paludine des Alpes <\/strong>(Viviparus ater)\u00a0<\/strong><\/em><\/h5>

The Alpine Paludina has a spiral-shaped, conical, brownish-black shell with a watertight seal that enables it to close its shell hermetically and protect it from drought.<\/p>

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Planorbe sp. <\/strong>(Planorbidae)<\/em><\/h5>

The shell of planorbes is round and flattened into a spiral shape.
Many species can be observed in Lake Geneva, most of which are indigenous.<\/p>

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Hydrobia from the antipodes <\/strong>(Potamopyrgus antipodarum)\u00a0<\/strong><\/em><\/h5>

The Antipodean Hydrobia has a dark brown or grey shell with 7 to 8 curved turns.
This species is native to New Zealand, with populations of up to 20,000 individuals per square metre.<\/p>

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Bivalves<\/strong><\/h4>

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Anodont sp. <\/strong>(Unionidae)\u00a0<\/strong><\/em><\/h5>

The largest mollusc in Lake Geneva.
Quagga mussels tend to cling to it, which limits its ability to move and filter.<\/p>

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Asian Corbicula <\/strong>(Corbiculas fluminalis)\u00a0<\/strong><\/em><\/h5>

The Asian Corbule has a rounded, pale yellow or brown shell. The growth lines are clearly marked.
This mollusc can be eaten like a clam.<\/p>

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Zebra mussel and Quagga mussel <\/strong>(Dreissena polymorpha and Dreissena bugensis)\u00a0<\/strong><\/em><\/h5>
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The Zebra Mussel has a zebra-covered shell and a flat base, while the Quagga Mussel has brownish and whitish zebra stripes and a rounded base.
These mussels arrived from Eastern Europe on boats, either clinging to the hulls or carrying their larvae in the water inside the boats.<\/p>

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Although they are not indigenous, they have allowed the return of a bird, the scaup, which particularly appreciates them.<\/p>

Be careful, they're very sharp!<\/p>

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Media gallery<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\tNative bivalve colonised by the quagga mussel. \n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\n\t\t\t\t\t
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\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\tQuagga mussels photographed in Lake Geneva\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\n\t\t\t\t\t
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\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\tCrayfish on a bed of quagga mussels\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>","protected":false},"excerpt":{"rendered":"

Mollusques Vous trouverez ici des informations sur les mollusques que l\u2019on peut observer dans le L\u00e9man. Photo : Marc Bernard esp\u00e8ces pr\u00e9sentes dans le L\u00e9man 0 de Moules quagga dans le L\u00e9man (estimation 2024) 0 t Les mollusques du L\u00e9man Vous trouverez d\u2019autres informations sur les mollusques du L\u00e9man dans le num\u00e9ro 113 de notre […]<\/p>\n","protected":false},"author":4,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"elementor_header_footer","meta":{"_acf_changed":false,"_seopress_robots_primary_cat":"","_seopress_titles_title":"","_seopress_titles_desc":"","_seopress_robots_index":"","footnotes":""},"class_list":["post-20396","page","type-page","status-publish","hentry"],"acf":[],"ase":null,"_links":{"self":[{"href":"https:\/\/asleman.org\/en\/wp-json\/wp\/v2\/pages\/20396","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/asleman.org\/en\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/asleman.org\/en\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/asleman.org\/en\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/asleman.org\/en\/wp-json\/wp\/v2\/comments?post=20396"}],"version-history":[{"count":31,"href":"https:\/\/asleman.org\/en\/wp-json\/wp\/v2\/pages\/20396\/revisions"}],"predecessor-version":[{"id":21351,"href":"https:\/\/asleman.org\/en\/wp-json\/wp\/v2\/pages\/20396\/revisions\/21351"}],"wp:attachment":[{"href":"https:\/\/asleman.org\/en\/wp-json\/wp\/v2\/media?parent=20396"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}