Die Hebräische Walze oder Hebräische Walzenschnecke (Voluta ebraea) ist eine Schnecke aus der Familie der Walzenschnecken (Gattung Voluta), die an der Küste Brasiliens verbreitet ist. Sie ernährt sich von Schnecken und Muscheln.
Das eikreiselförmige, dicke, axial gerippte Schneckenhaus von Voluta ebraea, das bei ausgewachsenen Schnecken eine Länge von etwa 10 bis 15 cm, ausnahmsweise auch über 20 cm erreicht,[1] hat ein kegelförmiges, knotig höckeriges Gewinde mit höckerigen Umgängen und eine Columella mit 5 Falten, von denen die unteren am größten sind. Die Umgänge sind oben an der Kante mit großen Höckern gekrönt. Die blass gelbbraune Oberfläche des Gehäuses ist mit spiralig verlaufenden braunroten, welligen Linien gezeichnet, die in gedrängten Binden stehen.[2][3]
Das hornige Operculum ist zugespitzt eiförmig und bedeckt einen Teil der Gehäusemündung.
Die Schnecke ist wie das Gehäuse weißlich und mit einem ähnlichen Muster aus dunkelbraunen Linien gezeichnet. Sie hat einen großen, kräftigen Fuß und einen langen Sipho.[1]
Die Hebräische Walze lebt im westlichen Atlantischen Ozean an der Küste Brasiliens.[1] Von der Notenschnecke der Karibik ist sie durch die Süßwasserbarriere an der Amazonasmündung isoliert.[4]
Die Hebräische Walze lebt in der Gezeitenzone und bis in 40 m Tiefe, vorwiegend auf sandigem Untergrund, doch ist sie auch auf Felsen, auf Sand zwischen Algen und auf Schotter zu finden. Sie fehlt in Wasser mit zu geringem Salzgehalt.[1]
Voluta ebraea frisst Muscheln und Schnecken. Auf Riffen vor Cabo Branco (João Pessoa, Paraíba) beobachtete Hebräische Walzenschnecken sind tagaktiv und fressen Herzmuscheln (Trachycardium muricatum), wobei sie die Beute offensichtlich durch chemische Reize wahrnehmen. Bei der Annäherung an die Muschel hebt die Schnecke die Vorderkante ihres Fußes und begräbt sie darunter.[1]
Wie andere Neuschnecken ist Voluta ebraea getrenntgeschlechtlich. Das Männchen begattet das Weibchen mit seinem Penis. Das Weibchen befestigt seine durchscheinenden, halbkugeligen Eikapseln, die einen Durchmesser von etwa 18 mm (15 bis 30 mm) haben, mit der flachen Seite einzeln an einem festen Substrat, nach Beobachtungen in Seegraswiesen am Strand von Paracurú (Ceará) an der Grünalge Udotea occidentalis. Eine Eikapsel enthält etwa 5 Eier in einem eiweißreichen Nährmedium. Das Veliger-Stadium, währenddessen der Embryo mit seinem Velum einen ständigen Flüssigkeitsstrom erzeugt und dabei Nährflüssigkeit aufnimmt, wird in Gänze innerhalb der Eikapsel durchlaufen. Pro Kapsel entwickeln sich 2 bis 5 (durchschnittlich 3) Schnecken. Nach mehreren Wochen schlüpfen durch eine Öffnung in der Mitte der Kapsel, die durch eine Naht mit dem Rand verbunden ist, junge fertige Schnecken, die nach Messungen in Paracurú etwa 8 mm lange Gehäuse mit etwa 2 ¼ Windungen haben. Wegen des fehlenden pelagischen Veliger-Stadiums hat die Schnecke ein begrenztes Verbreitungsgebiet.[5]
Trotz ihrer dicken Schale hat Voluta ebraea Feinde. Zu den wichtigsten Fressfeinden gehören Kraken, darunter der Gemeine Krake.[6]
Voluta ebraea wird wegen ihres Gehäuses gesammelt, das als Schmuck verkauft wird. Darüber hinaus wird das Fleisch gegessen. Wegen Überfischung wird die Art als gefährdet eingestuft. Auf Grund ihrer relativ geringen Anzahl an Nachkommen und wegen des fehlenden pelagischen Veliger-Stadiums kann sie verlorene Lebensräume nur schwer wieder besiedeln. Ein Schlüssel für den Erhalt der Art wird im Schutz der Gelege gesehen.[5]
Die Hebräische Walze oder Hebräische Walzenschnecke (Voluta ebraea) ist eine Schnecke aus der Familie der Walzenschnecken (Gattung Voluta), die an der Küste Brasiliens verbreitet ist. Sie ernährt sich von Schnecken und Muscheln.
Voluta ebraea, common name the Hebrew volute, is a species of medium-sized sea snail, a marine gastropod mollusk in the family Volutidae, the volutes. The Hebrew volute is endemic to Brazil, where it is collected both for food and for its shell, which is highly desired for ornamental purposes. Recent studies indicate that natural populations of Voluta ebraea may be suffering declines due to overfishing and overexploitation.
This sea snail is found only along the north and northeastern Brazilian coast in the littoral zone. This species is endemic to those areas. It is present in many Brazilian states and regions, including Pará, Maranhão, Ceará, Rio Grande do Norte, Paraíba, Pernambuco, Alagoas, Sergipe, Bahia and Abrolhos Marine National Park.[4][7][8]
The shell length of this species may reach and exceed 200 mm,[9] up to 220 mm,[7] although lengths from 100 mm to 150 mm are more common.[8]
Voluta ebraea has a somewhat robust and solid shell, with a slightly elongate contour. It is colored cream externally, with a complex series of darker-reddish brown markings and lines that are said to resemble Hebraic figures.[4] The interior of the shell can vary in color from pale to strong orange. The protoconch is rounded, and presents two whorls. The shell as a whole has seven slightly convex whorls.[4] Those whorls (including the body whorl) are ornamented by several posteriorly-oriented sharp spines. The outer lip is thick, and the aperture is relatively long and narrow. As is the case in other volutes, the columella presents an array of strong oblique columellar folds (also known as plicae, 9 to 11 of them in this species[4]), which are more conspicuous anteriorly. The corneous, claw-like operculum partially covers the shell aperture.[8]
Sexual dimorphism can be observed in the shells of this species: the shells of the males tend to be more elongate with a smoother outer surface, whereas the shells of the females are generally wider and more nodulose.[4] The angle of the spire also differs between males and females.[4]
The Hebrew volute has a pale ivory colored body, ornamented by numerous irregular and intertwined thin dark-red to brown colored lines, and several small spots of the same color along the sides of the foot. Some of the most distinct external features are its very large foot, and a long siphon.[8][10]
This species presents a Steoglossan type radula, composed of a single row of rachidian or central teeth. Each one of these teeth exhibits several smaller acute denticles or cusps. The radula is considered to be similar, though larger than that of the music volute, a similar but distinct species.[10]
Much is yet to be revealed about the ecology of V. ebraea, as studies on that subject are fairly recent and/or rather scarce.
The Hebrew volute dwells in sandy bottoms, among coral and rocks,[7][9] and usually shows a preference for sandy substrata.[4][11] It may be found from shallow water to depths around 40–70 m[7][9] and is commonly taken by shrimp trawlers.
Like other members of the clade Neogastropoda, Voluta ebraea is dioecious,[12] which means each individual organism belonging to this species is distinctly male or female. It is also sexually dimorphic,[9] which means there is a difference in form between individuals of different sex within this species.
As is the case in several other volutids, the Hebrew volute is carnivorous and predatory. It is known to feed on the cardiid bivalve mollusk Trachycardium muricatum in the wild,[9] whereas in captivity it has been reported to feed on the sea snails Stramonita haemastoma (a muricid carnivorous gastropod) and Tegula viridula (a top snail).[13]
The Hebrew volute is known to be a prey of the Bocon toadfish, Anphichthys cryptocentrus.[14]
The flesh of Voluta ebraea is edible,[4] and it is locally collected for food in many areas. Its shell is also considered a popular and beautiful decorative object, and is sold as souvenir in local markets and craft stores in several regions of Brazil.[9]
Though little is known about the conservation status of this species, it is believed that both overfishing and overexploitation are exerting a negative effect on natural populations. The Hebrew volute may occur in shallow water, which tends to facilitate its harvesting by the locals. Thus it is currently not observed in many areas in which it was known to be numerous before.[9] It is not uncommon for Hebrew volutes to be accidentally caught in bottom gill fishing nets and traps set by commercial fishing boats.[15]
The imposex phenomenon has been observed in the Voluta ebraea.[12] The development of masculine sexual organs in the females exposed to organic tin compounds, such as tributyltin (TBT), may have several negative consequences for entire populations of this species, from sterilization of individuals to the complete extinction of those populations. Such compounds are biocide and antifouling agents, commonly mixed in paints to prevent marine encrustations on boats and ships. Therefore, it is not uncommon for high concentrations of such compounds to be present in the sea water near shipyards and docking areas, consequently exposing the nearby marine life to its deleterious effects.[12]
Voluta ebraea, common name the Hebrew volute, is a species of medium-sized sea snail, a marine gastropod mollusk in the family Volutidae, the volutes. The Hebrew volute is endemic to Brazil, where it is collected both for food and for its shell, which is highly desired for ornamental purposes. Recent studies indicate that natural populations of Voluta ebraea may be suffering declines due to overfishing and overexploitation.
Voluta ebraea is een slakkensoort uit de familie van de Volutidae.[1] De wetenschappelijke naam van de soort is voor het eerst geldig gepubliceerd in 1758 door Linnaeus.
Bronnen, noten en/of referenties
Voluta ebraea (nomeada, em inglês, hebrew volute[3][4] e, em língua indígena, no Brasil, atapu, guatapi ou itapu)[5] é uma espécie de molusco gastrópode marinho pertencente à família Volutidae. Foi classificada por Carolus Linnaeus em 1758.[1] Sua distribuição geográfica abrange o oeste do oceano Atlântico, endêmica da região norte e região nordeste do Brasil, entre o Pará e a Bahia.[2] Esta espécie de caramujo atinge até os 15[3][4] ou 18[6] centímetros de comprimento. É espécie que pode ser usada na alimentação humana.[2]
Concha robusta, com espiral moderadamente alta, de até 7 voltas, e protoconcha arredondada. Sua superfície apresenta coloração creme e diversos desenhos característicos de coloração marrom e laranja a marrom-avermelhada, dotada de esculturas de crescimento visíveis, em protuberâncias pontiagudas, fortes e destacadas, dirigidas para a espiral; chegando até sua volta final (9 a 11), que apresenta abertura longa e moderadamente estreita, angular, ocupando 2/3 de toda a concha (quase a totalidade do seu comprimento) e com opérculo ocupando 1/4 da abertura, quando vista por baixo, possuindo um lábio externo levemente espessado e columela curva, com nove a onze fortes pregas oblíquas. Canal sifonal curto e afunilado.[2][4][7]
Fotografia mostrando espécime de V. ebraea em museu de Phuket.
É encontrada em costas arenosas, da zona entremarés à zona nerítica, entre rochas e corais com até 40 metros de profundidade.[2][8]
Segundo Rios (1994), existe dimorfismo sexual nesta espécie de caramujo, com fêmeas mais nodulosas e alargadas que os machos, estes mais lisos e alongados.[2]
Segundo Eurico Santos, a denominação atapu também é citada para a espécie de molusco Cassidaeː Cassis tuberosa, da mesma região.[9]
Fotografia mostrando espécime de V. ebraea, o atapu, na coleção do Museu de Zoologia da USP, em São Paulo.
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|acessodata= requer |url= (ajuda) |coautor= (ajuda); |acessodata= requer |url= (ajuda) |acessodata= requer |url= (ajuda) |coautor= (ajuda); |acessodata= requer |url= (ajuda) Voluta ebraea (nomeada, em inglês, hebrew volute e, em língua indígena, no Brasil, atapu, guatapi ou itapu) é uma espécie de molusco gastrópode marinho pertencente à família Volutidae. Foi classificada por Carolus Linnaeus em 1758. Sua distribuição geográfica abrange o oeste do oceano Atlântico, endêmica da região norte e região nordeste do Brasil, entre o Pará e a Bahia. Esta espécie de caramujo atinge até os 15 ou 18 centímetros de comprimento. É espécie que pode ser usada na alimentação humana.
A espécie V. ebraea tem como habitat as águas tropicais da região nordeste da América do Sul, no Brasil.
