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California Fish and Game regulations (1979) have set limits on the amount of moon snails taken, and none can be taken north of the Golden Gate Bridge (in San Francisco). The small crab, Opisthopus transversus, is sometimes found as a commensal of the snail, and hermit crabs are known to inhabit the empty shells. (Morris, et al, 1983)
US Federal List: no special status
CITES: no special status
Even though moon snails feed on clams, there has been no impact on littleneck clam farming. (B. Hartwick, personal communication)
They are eaten by humans and other animals. (Morris, et al, 1983)
The moon snail's method of obtaining food is varied. They feed mostly on clams, mussels, or other mollusks. Moon snails usually clamp the foot around clam shells and proceed with drilling a hole with their radula, which is a long, ribbon-like tongue containing thousands of teeth (denticles) that project from the mouth opening. It is suspected that the foot smothers its victims to make their job easier. Studies indicate there is an enzyme secretion of carbonic anhydrase that has a softening effect on mollusk shells to aid in drilling. Food is extracted by sucking the foot over the hole, or by sucking through the siphon of a clam. Young snails feed on diatoms, and on green seaweed called Ulva, at 10-12 m depth for five to six months. Afterwards, they begin to hunt animal prey in the substratum. They do not venture into shallower water until their shell lengths reach about 30 mm. (Morris, et al, 1983; Buchbaum & Milne, 1962; Shaefer, 1997; Ricketts & Calvin, 1962; Anonymous, 2000)
Lewis's Moon Snail, Euspira lewisii, ocupies the Pacific Ocean coast, from Vancouver Island (British Columbia) to Isla San Geronimo (Baha California, Mexico).
Biogeographic Regions: nearctic (Native ); pacific ocean (Native )
Moon snails are inhabitants of soft sand or mud along the Pacific coast in protected bays, low intertidal areas, in the substratum off the coast to a depth of about 150 m. More snails are at the surface at night than during the day. They are found at the surface after heavy rains, but remain buried in cold weather. (Morris, et al, 1983)
Aquatic Biomes: coastal
Shell size up to 130 mm in diameter, or approximately 5 inches, although though usually 4 inches or less due to picking. A fully expanded animal is several times larger than its shell, which almost completely covers the body. Shell shape is globe-like, with shallow groove at the shoulder of whorls; columella with a calcereous callus reaching to edge of deep umbilicus. Shell color is yellowish with thin brown periostracum; the horny door (operculum) common to snails is dark brown. The snails plough forward with a foot just below the surface of the sand. When extended, the foot can measure over 12 inches in diameter. It is heavily ciliated, has mucus glands, and is very effective for moving over a shifting bottom. The mucus foot can fold into a grasping organ to hold prey. The foot also can be drawn inside the shell by an aquiferous system, but the snail cannot stay inside the shell for long periods of time because it cannot breathe. Life expectancy of this snail is estimated to be several years. (Morris et al., 1983; Ricketts & Calvin, 1962; Anonymous, 2000; J. Kirkhart, personal communication)
Average mass: 435 g.
Other Physical Features: ectothermic ; bilateral symmetry
Males are smaller than females and their shells are slightly thicker. They begin to mate when they reach a shell length of 55 mm. Eggs are laid in a broad, rubbery "sand collar" about 15 cm diameter which forms around the shell and foot. This collar holds a layer of eggs (eggs are 250 micrometers in diameter) which is then deposited by ocean waves on the beach. The mucus collar is coated by layers of sand held together by the mucus. Moon snails lay eggs in shallow water in spring and summer, and eggs hatch in midsummer. A half-million or so larvae swim around inside the sand collar for several weeks until being released by disintegration of the collar. Young snails feed on diatoms, and on green seaweed called Ulva, at 10-12 m depth for five to six months. Afterwards, they begin to hunt animal prey in the substratum. They do not venture into shallower water until their shell lengths reach about 30 mm. (Morris, et al, 1983; Buchbaum & Milne, 1962; Shaefer, 1997)
Die Lewis-Mondschnecke oder Lewis-Nabelschnecke (Lunatia lewisii) ist eine Schnecke aus der Familie der Mondschnecken, die an der Pazifikküste Nordamerikas lebt. Mit bis zu 13 cm Gehäusedurchmesser ist sie die größte Art der Familie.
Das kugelige Schneckenhaus von Lunatia lewisii, das bei ausgewachsenen Schnecken bis zu 13 cm Durchmesser erreicht, hat einen tiefen Nabel, an dessen Kante von der Columella her ein Callus reicht. Nach oben zur Naht hin verläuft eine flache Rinne. Die Grundfarbe ist gelb, das dünne Periostracum braun. Es gibt deutlich sichtbare Zuwachsstreifen und keine weitere Gehäusezeichnung. Das dunkelbraune Operculum ist hornig.
Beim Kriechen ist das Schneckenhaus fast vollständig vom Mantel bedeckt. Das aktive Tier kann seinen Fuß auf das vierfache Volumen des Gehäuses ausdehnen. Hierbei hilft ihm das für Mondschnecken kennzeichnende Sinussystem, das bei dieser Art 40 bis 80 mit Schließmuskeln versehene Poren aufweist. Bindegewebe entlang der Sinus verhindert Kontakt des einströmenden Meerwassers mit Nerven, Muskelgewebe oder Blut. Bei Störung wird das Wasser in Sekundenschnelle ausgestoßen, so dass sich die verkleinerte Schnecke vollständig ins Haus zurückziehen und dieses mit dem Operculum verschließen kann.
Die Lewis-Mondschnecke tritt an der Pazifikküste Nordamerikas von British Columbia (Kanada) bis zur Isla San Jerónimo (Baja California, Mexiko) auf.
Lunatia lewisii lebt in geschützten Buchten, unteren Bereichen der Gezeitenzone und unterhalb in Tiefen von bis zu 150 Metern auf sandigem oder schlammigem Untergrund. Bei Nacht sind mehr Schnecken aktiv als bei Tag. Sie kommen nach starkem Regen zum Vorschein und bleiben bei kaltem Wetter im Sand vergraben.
Es gibt etwa gleich viele männliche und weibliche Jungschnecken, doch die Männchen sterben früher. Männchen sind eher kleiner und haben dickwandigere Gehäuse. Unter den Schnecken mit 10 cm Gehäuselänge sind bereits 90 % Weibchen. Ab einer Gehäuselänge von etwa 5,5 cm beginnen die Schnecken sich zu paaren. Die kragenförmigen, aus Sand und Gallerte gebildeten Gelege sind etwa 2 mm dick und haben an der Basis einen Durchmesser von etwa 20 cm, am oberen Rand dagegen nur rund 7,5 cm. Die Eikapseln sind rund 200 bis 250 μm groß und enthalten jeweils ein Ei. Es gibt keine Nähreier. Die schlüpfenden Veliger-Larven haben eine Gehäuselänge von etwa 180 μm. Anfangs schwimmen sie noch in den Hohlräumen der Gallertmasse, bis diese auseinanderfällt. Sodann durchlaufen sie bis zu ihrer Metamorphose zur fertigen Schnecke eine sehr kurze pelagische Phase.[1] Nach Beobachtungen vor Nanaimo (Vancouver Island) fressen frisch metamorphosierte Schnecken in 10 bis 12 m Tiefe auf Wasserpflanzen wachsende Diatomeen und später auch Seetang. In einem Alter von 5 bis 6 Monaten bei 5 bis 6 mm Schalenlänge gehen sie dazu über, im Sandboden kleine Muscheln zu jagen. Bei 3 cm Gehäuselänge suchen sie auch flacheres Wasser auf. Die Schnecken werden mehrere Jahre alt.
Wie bei anderen Mondschnecken bilden Muscheln eine bevorzugte Beute von Lunatia lewisii. In Nanaimo (Vancouver Island) bilden die Arten Protothaca staminea und Clinocardium nuttallii den Großteil der Nahrung, in Bodega Bay (Kalifornien) ist es Macoma nasuta. Die Beute wird gesucht, indem die Schnecke mit ihrem Propodium den Sand in Zickzackbewegungen durchpflügt. Unverletzte Muscheln werden aus 15 cm Entfernung wahrgenommen, Fleisch ohne umhüllende Schale aus 2 Metern. Das Opfer wird mit dem Fuß umfasst und sodann unter Säureeinwirkung mit der Radula ein Loch in die Schale gebohrt. An der unteren Lippe der Proboscis befindet sich eine Drüse (ABO, accessory boring organ), deren saures Sekret den Kalk auflöst. Raspeln mit der Radula und Säureeinwirkung wechseln sich ab, bis das Loch gebohrt ist. Dieser Vorgang kann mehrere Stunden dauern und findet eingegraben im Sand statt. Nach einer Mahlzeit verbleibt die Schnecke bis zu 24 Stunden im Sand, bis sie davonkriecht. Im Labor fressen Lewis-Mondschnecken alle vier Tage eine große Muschel. Durch Mondschnecken gebohrte Löcher sind auf einer Seite breiter als auf der anderen.
Die Lewis-Mondschnecke oder Lewis-Nabelschnecke (Lunatia lewisii) ist eine Schnecke aus der Familie der Mondschnecken, die an der Pazifikküste Nordamerikas lebt. Mit bis zu 13 cm Gehäusedurchmesser ist sie die größte Art der Familie.
Neverita lewisii (previously known as Polinices lewisii, Lunatia lewisii, Euspira lewisii), common name Lewis's moon snail, is a species of large operculated sea snail. It is a predatory marine gastropod in the family Naticidae, the moon snails.[1] Traditionally, this species was assigned to either the genus Lunatia, the genus Polinices or the genus Euspira. Recently, it was assigned to the genus Neverita based on molecular data.[1][2]
This is the largest species in the family.
Neverita lewisii lives in the Eastern Pacific, from British Columbia to northern Baja California, Mexico.
This snail is found intertidally and at depths of up to 180 metres (590 ft), usually ploughing through the substrate looking for prey.
The shell of this species can grow to 14 centimetres (5.5 in) across, the largest of the moon snails. It has an extremely large foot, which when the snail is active, is extended up over the shell and mantle cavity. Part of the propodium contains a black-tipped siphon which leads water into the mantle cavity. The cephalic tentacles, located on its head, are usually visible above the propodium.
When the animal retracts its soft parts into the shell, a lot of water is expelled, thus it is possible to close the shell with its tight-fitting operculum.
Neverita lewisii feeds mainly on bivalve molluscs by drilling a hole in the shell with its radula and feeding on the organism's soft flesh.
Like other moon snails, this species lays its eggs in a "sand collar". The eggs may number in the thousands and hatch into microscopic larvae which feed on plankton until they undergo torsion and metamorphose into the adult stage.
Neverita lewisii (previously known as Polinices lewisii, Lunatia lewisii, Euspira lewisii), common name Lewis's moon snail, is a species of large operculated sea snail. It is a predatory marine gastropod in the family Naticidae, the moon snails. Traditionally, this species was assigned to either the genus Lunatia, the genus Polinices or the genus Euspira. Recently, it was assigned to the genus Neverita based on molecular data.
This is the largest species in the family.
Neverita lewisii is een slakkensoort uit de familie van de Naticidae.[1] De wetenschappelijke naam van de soort is voor het eerst geldig gepubliceerd in 1847 door Gould.
Bronnen, noten en/of referenties
Neverita lewisii (denominada, em inglês, Lewis' moon snail[2][3][4][5] ou Western moon snail)[2] é uma espécie predadora de molusco gastrópode marinho do leste do oceano Pacífico, na América do Norte;[2][3][5] pertencente à família Naticidae da ordem Littorinimorpha. Foi classificada por Augustus Addison Gould com o nome Natica lewisii, em 1847, no texto "Descriptions of the following Shells, from the collection of the Exploring Expedition"; publicado nos Proceedings of the Boston Society of Natural History, 2; páginas 237-239.[1] Os malacologistas S. Peter Dance e R. Tucker Abbott (1982) citam esta espécie como "o maior Naticidae extante";[3] no passado, e até o século XXI, também acrescentada aos gêneros Euspira, Lunatia ou Polinices.[1]
Concha pesada, rotunda e sólida, de coloração castanha, alaranjada, amarelada a cinzenta, frequentemente manchada e coberta de perifíton; de acabamento fosco e grosseiro, com visíveis linhas de crescimento e ápice castanho escuro; dotada de espiral baixa e com até 16.6 centímetros de comprimento, quando desenvolvida. Por baixo é visível um umbílico profundo, com uma pequena parte coberta, próximo à sua columela e ao seu lábio externo, que é pouco engrossado; com abertura, próxima, dotada de um opérculo, córneo e castanho, que fecha totalmente a abertura semicircular, sem canal sifonal, da sua concha.[2][4][6][7]
A espécie vive em substrato arenoso, onde se enterra, e que vai da zona entremarés até uma profundidade de 50 metros;[3][4][5][8] entre pradarias de ervas marinhas. Esses grandes caramujos formam características fitas de areia, cimentadas com muco e onde se encontram seus ovos.[6][9]
Neverita lewisii ocorre no Pacífico Oriental, entre a Colúmbia Britânica, no Canadá, até a península da Baixa Califórnia, no México;[2][5] com sua localidade-tipo em Puget Sound, Washington, noroeste dos Estados Unidos.[10]
A etimologia de lewisii está contida num trecho da descrição original da espécie (página 239), onde há o relato de que "espécimes foram trazidos da desembocadura do rio Columbia por Lewis e Clark", uma dupla de exploradores que lideraram a primeira grande expedição exploratória do continente norte-americano, rumo ao oeste, sendo o epíteto específico uma homenagem a Meriwether Lewis.[11]
Neverita lewisii (denominada, em inglês, Lewis' moon snail ou Western moon snail) é uma espécie predadora de molusco gastrópode marinho do leste do oceano Pacífico, na América do Norte; pertencente à família Naticidae da ordem Littorinimorpha. Foi classificada por Augustus Addison Gould com o nome Natica lewisii, em 1847, no texto "Descriptions of the following Shells, from the collection of the Exploring Expedition"; publicado nos Proceedings of the Boston Society of Natural History, 2; páginas 237-239. Os malacologistas S. Peter Dance e R. Tucker Abbott (1982) citam esta espécie como "o maior Naticidae extante"; no passado, e até o século XXI, também acrescentada aos gêneros Euspira, Lunatia ou Polinices.
