Trivia monacha | The Conchological Society of Great Britain and Ireland

<p><em>Trivia monacha</em> (da Costa, 1778)</p>

Trivia monacha

Species

Photographer / copyright holder

Steve Wilkinson

Length = 10mm. Collected from Porthcurno, Cornwall on Aug-82.

Trivia monacha

Species

Photographer / copyright holder

Steve Wilkinson

Length = 11mm. Collected from Porthcurno, Cornwall on Aug-82.

6.5mm juv., 10mm juv., 12mm juv., 10.2mm adult, 12 mm adult. LWS, Scapa Flow, Orkney. As shell grows, body whorl extends towards the spire eventually overwhelming it, while the aperture becomes a slit. Last juv. stage can be larger than early adult.

Species

Photographer / copyright holder

I.F. Smith

All 26^th April 1975, except 12mm adult; 7^th Sept 1975.

Late juvenile. Height 12 mm. At this stage, spire almost enveloped by final whorl, signs of adult shell ridges developing, shell shape approaching that of the adult, but still the juvenile white. Late juvenile shells are often larger than early adults.

Species

Photographer / copyright holder

I.F. Smith

LWS, Scapa Flow, Orkney April 1975

Juvenile. Height 10 mm. At this stage, the aperture has become a slit, though relatively wider than on the adult. The spire is becoming enveloped by the final whorl, and there are signs of adult shell ridges developing. LWS Scapa Flow, Orkney April 1975.

Species

Photographer / copyright holder

I.F. Smith

Trivia monacha early juvenile. At this stage, the shell has a typical gastropod spire and aperture. Height (apex to end of aperture) 6.5 mm. LWS, Scapa Flow, Orkney April 1975

Species

Photographer / copyright holder

I.F. Smith

Trivia monacha. Top left to bottom right: 6.5mm juv., 10mm juv., 12mm juv., 10.2mm adult, 12 mm adult. LWS Scapa Flow, Orkney, all on 26th April 1975, except 12mm adult 7th Sept 1975. The last juvenile stage can be larger than the early adult stage.

Species

Photographer / copyright holder

I.F. Smith

Trivia monacha adult shell cut open to show internal coiled juvenile shell. A very small rise on the outer adult shell indicates the position of the enveloped juvenile spire apex. LWS, Scapa Flow, Orkney Sept. 1975

Species

Photographer / copyright holder

I.F. Smith

Trivia monacha adult shell. The central one of the three dark marks on the dorsum is indistinct on this specimen. 10.2 mm high (longest dimension). LWS, Scapa Flow, Orkney April 1975

Species

Photographer / copyright holder

I.F. Smith

Trivia monacha adult shell. The diagnostic three dark marks on the dorsum are variable in intensity. Shell is shiny as protected from water much of the time by the mantle. Specimen 12 mm high (longest dimension). LWS, Scapa Flow, Orkney Sept. 1975

Species

Photographer / copyright holder

I.F. Smith

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