Lacuna vincta (Montagu 1803)

Die Gebänderte Grübchenschnecke (Lacuna vincta) ist eine Schnecke aus der Unterfamilie der Grübchenschnecken (Ordnung Sorbeoconcha), und weist viele ähnliche Merkmale wie die Flache Grübchenschnecke auf. Der Name kommt von roten Spiralbändern auf dem Gehäuse.

Aussehen

Das Tier hat ein zartes und kegelförmiges Haus in gelb oder aber auch in rotbraun, dazu noch rote Spiralbänder, der Nabel des Gehäuses dagegen ist weiß. Dieser ist im Vergleich zu der oben schon genannten, verwandten Art, der Flachen Grübchenschnecke, wesentlich enger. Das Haus hat bis zu fünf Umgänge, die aber wenig gewölbt sind, deshalb ergibt sich auch nur eine Höhe von einem Zentimeter. Die Mündung ist weit und eiförmig, sie hat in etwa die Hälfte der Höhe des Gehäuses.

Vorkommen

Auf flächigen Algen, ganz besonders auf Laminarien an geschützt gelegenen Küsten findet man diese Art. Die Schnecken tummeln sich an den Gewässerrändern des Atlantiks und seiner Seitenmeere Ärmelkanal, Nordsee und westliche Ostsee. Diese Schnecke ist an algenreichen Küsten recht häufig anzufinden.

Lebensweise

Ganz im Gegensatz zur Flachen Grübchenschnecke, wo das Weibchen die doppelte Größe des Männchens erreicht, sind bei der Art Lacuna vincta beide Geschlechter gleich groß. Kennzeichnend sind die weißgelben bis rosa gefärbten, ringförmigen Eigelege die im Frühling zu finden sind. Dieses merkwürdige Gelege wird auf großflächigen Algen abgesetzt, besonders die angespülten Tange aus der Dauerflutzone sind beliebte Plätze und oftmals dicht besetzt mit Laichringen.

Aus den Eiern schlüpfen schließlich kleine Schwimmlarven, Veliger genannt, die vor der Entwicklung zur Schnecke und dem damit verbundenen Bodenleben erst einmal zwei bis drei Monate im Plankton des Meeres herumtreiben.

Quellen

Taxonomie:

• Costello, M.J.; Bouchet, P.; Boxshall, G.; Emblow, C.; Vanden Berghe, E. (2004). European Register of Marine Species (http://www.marbef.org/data/erms.php), abgerufen am 21. November 2006. Datensatz

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Lacuna vincta, commonly known as northern lacuna, wide lacuna, northern chink shell,^[2] or banded chink shell,^[3] is a species of sea snail, a marine gastropod mollusk in the family Littorinidae, the winkles or periwinkles. It is found intertidally and in shallow waters in both the northern Atlantic Ocean and the northern Pacific Ocean. It is a herbivore, feeding on seaweed and diatoms with its toothed radula.

Description

The shell of Lacuna vincta is conical, with five to six smooth whorls and a pointed apex. The aperture is about half the height of the shell or slightly larger. The umbilicus has a prominent groove between two white ridges of columella. The exterior of the shell is pale brown with a broad spiral of white and a glossy periostracum. The interior of the shell is not white and pearly and the aperture can be closed by an operculum.^[2][3] The maximum recorded shell length is 13 mm (0.5 in).^[4]

Distribution and habitat

The distribution of L. vincta is circumboreal, extending as far south in the Atlantic Ocean as the British Isles and France, and the eastern coast of North America.^[3] In the northeastern Pacific its range extends from Alaska to California, but it is seldom found further south than Washington state. It is present on algae on rocky shores, intertidally and down to about 40 m (130 ft).^[3] In the British Isles, the larvae settle preferentially on brown seaweed such as Fucus serratus and Laminaria spp. and on short red seaweed such as Lomentaria articulata, as well as on the seagrass Zostera spp.^[3] In the Pacific they settle mainly on kelp, eelgrass and surfgrass.^[2]

Ecology

L. vincta is a herbivore, grazing on seaweed and on diatoms living on the surface of seagrasses. The radula has 45 to 95 rows of tiny teeth, with about three new rows being formed each day. Two separate types of teeth are produced; if the snail is grazing on seaweed, these newly formed teeth are sharply pointed and are used to tear deeply into the algal frond; if on the other hand, the snail is currently feeding on diatoms growing on seagrass, the new teeth are much blunter and are used to scrape diatoms off the leaves.^[2] The new teeth are formed at the back of the radula and work their way forward as the older teeth wear away and are discarded, so it takes some time for the snail's teeth to adjust to a change in diet.^[2]

This snail favors sheltered positions and in exposed areas seeks the shelter of crevices or dense patches of seaweed.^[3] In unsuitable conditions, such as at times of food shortage or when there are excessive numbers of predators, it can produce a string of mucus which it uses as a "parachute" to help it to drift to a more favorable location.^[2]

The sexes are separate in this snail with eggs being laid in a ring on seaweed or seagrasses. They may be laid throughout the year but in some locations, such as the British Isles, they are laid in the spring and early summer after which the adults die. The eggs hatch in about six days and the veliger larvae are planktonic for up to six months before settling on the shallow seabed at a shell-length of about 1 mm (0.04 in).^[2] In eastern Canada these juvenile snails have been recorded at a density of 1500 per square meter.^[3]

References

De scheefhoren (Lacuna vincta) is een slakkensoort uit de familie van de Littorinidae.^[1] De wetenschappelijke naam van de soort is voor het eerst geldig gepubliceerd in 1803 door Montagu.

Lacuna vincta, trong tiếng Anh gọi là northern lacuna, wide lacuna, northern chink shell,^[2] hay banded chink shell,^[3] là một loài ốc biển, thuộc họ thân mềm chân bụng Littorinidae. Nó sống trong vùng gian triều và nước nông ở cả bắc Đại Tây Dương và bắc Thái Bình Dương. Đây là loài ăn thực vật, ăn cỏ biển và tảo silic.

Mô tả

Vỏ Lacuna vincta hình nón, có năm-sáu vòng xoắn với chóp nhọn. Lỗ mở dài chừng một nửa độ cao vỏ hoặc hơn chút. Mặt ngoài vỏ màu nâu nhạt với lớp sừng ngoài bóng láng, mặt trong không có màu trắng. Chúng có thể lấy nắp để bịt lỗ mở.^[2][3] Chiều dài vỏ tốt đa ghi nhận được là 13 mm (0,5 in).^[4]

Phân bố và môi trường sống

L. vincta phân bố trong vùng circumboreal, lan về xa tận vùng Đại Tây Dương quanh quần đảo Anh và Pháp, và bờ biển miền đông Hoa Kỳ.^[3] Ở miền đông bắc Thái Bình Dương, nó có mặt trong vùng biển từ Alaska tới California, dù ít khi xuất hiện trong vùng biển phía nam bang Washington. Nó hiện diện trong nơi ven bờ lắm đá sỏi, từ vùng gian triều đến chỗ sâu 40 m (130 ft).^[3] Tại quần đảo Anh, ấu trùng thích bám trên tảo nâu như Fucus serratus và Laminaria spp., trên tảo đỏ như Lomentaria articulata, và trên cỏ biển Zostera spp.^[3] Ở Đại Tây Dương, chúng bám trên tảo bẹ, Zostera spp. và Phyllospadix spp..^[2]

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