Aquarienschnecken.de

Pachymelania aurita (O.F. Müller, 1774)

Description:

The thick-walled stable shell grows up to 60 mm in length. There are straight-pointed spikes in spiralling rows, which can be more or less pronounced. There is a faint suture. The paucispiral operculum has an eccentric basal nucleus. The color varies between yellow and brown tints.

In the paragraph Additional information the different coloration of the snails depending on their location is dealt with.

The distance between the spiky rows is considerably larger as with Pachymelania byronensis, and thus Pachymelania aurita has less spiky rows.

Range/Habitat:

This snail is found along the West African coast from Senegal to Angola. Pachymelania aurita lives on muddy sand soils in the open lagoons and avoids areas with a strong current. It lives at water depths of down to 5 m. Over the year, P. aurita experiences variations of salinity between 0 and 27%. It prefers the upper region of the infralitoral on especially sandy sediments.

Reproduction:

Their reproductive period starts during the dry season (December to April). Other than Melanoides sp. well-known to aquarists, the female Pachymelania does not bear "developed" snails – this has been proved at least for P.aurita and P. fusca.

After taking in the sperm the eggs are fecundated, the development takes place inside the mother snail up to the larval stage. Then the mother snail beds the larvae on plancton.

This phase takes about 7 days, after that the young snails live on the ground; this is not 100% sure, however, as there are two contradictory statements in literature – one says that larvae are released and bedded on plancton, the other says that egg strands are bedded on plancton (authors from AJAO and FAGADE)

Food:

The weak teeth and the fringed mantle border hint towards a filter feeder, which means that they eat microplancton.

Additional information:

BINDER (1977) researched the colored patterns on the shells of populations of Pachymelania aurita mainly in the Ebrié lagoon, but furtherly also in the lagoon of Grand Lahou (Ivory Coast). P. aurita has spiralling dark bands (black, dark brown, reddish, orange) on the basically yellow shell, however, it can also be totally light or dark in color. BINDER comes to the conclusion that the varying coloration is not due to a selection by predators, as they find the same conditions, i.e. turbid water, everywhere in the lagoon. He assumes that this phenomenon is a visible sign of the species' adaption to different ecological factors in its habitat. In the various areas there are different seasonal salinities.

This species is very well-known in Nigeria and is gathered and eaten by many ethnicities along the coast (exactly like Tympanotonus fuscatus) and even sold on markets. The young snails of this species are, moreover, an important part of the staple of snail-eating fish.

The species is very wide-spread despite large salinity variations in the largest part of the lagoon (Lagos) – from 20 to 30% in February (dry season) to about 0% in June (rainy season) – and despite the continuous change in the sediment composition on the ground (mostly in the north-west and the centre). In some places the population is very dense, often it is over 2000 snails per square meter. In February 1986 even 60,000 young snails could be gathered per square meter.

Disease transmission

The fact that this snail can transmit flukes causing bilharziosis should not be neglected.

Literature:

GLAUBRECHT, M. (1996): Evolutionsökologie und Systematik am Beispiel von Süß- und Brackwasserschnecken (Mollusca: Caenogastropoda: Cerithioidea): Ontogenese-Strategien, paläontologische Befunde und historische Zoogeographie. Backhuys Publishers, Leiden, NL. ISBN 90-73348-52-8.

[ Morphology, anatomy, reproductive biology – in German ]

Translation by Mathias Stein on the basis of:

 ZABI (G.S.JJ)et LE LOEWF(P.) > 1992 - Revue des connaissances sur la fauna benthique des millieux margino-litto-raux dÁfrique d´louest. 1- Biologie etecologie des especes.Rev., Hydrobiol.tropp., 25(3):207-249. Auf diesem Wege, vielen Dank :)

[ Detailed information about the habitat, anatomy, range and salinity ]

Web links

 sys tax

 gastropods. com

 members.aol.com/Mkohl2/Afropleuros.html

Author: Alexandra Behrendt Translator: Ulrike Bauer

This page was actualized on September 1, 2008

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