What affects colour of new shell growth?

[Dusk]

Just wondering if there's any data on what affects the colour of new shell growth in multi-coloured species . Amberdrake (margie) has one section of shell that's gorgeously chequered - it was near the edge when I got him - but the new growth since then is a completely different pattern. Some other snails have wide bands of one colour before going back to a set pattern. Is it entirely genetic (like horses) mixture of genes and environment (like cows), determined entirely by diet (flamingos? ) or something else?

[coyote]

For wc garden snails I've had, I've seen distinct changes in shell coloration after I got them on the subsequent new growth. So I don't think it's completely genetic, because diet and/or environment seems to have an influence.

[kanin]

I've observed great differences of shell colouring in Helix Pomatia on the Islands Öland and Gotland compared to those that dwell on the swedish mainland. The Pomatias on those two Island turn white long before they reach maturity, and their birthcolouring and early colouring are much lighter than those of the mainland. I believe that this is caused by diet, as both Öland and Gotland has very high levels of calclium in it's soil. The possibility of this being genetical is slim as Pomatias was implanted in sweden, öland and gotland, and thereby not been separated long enough to develeop this feature.

[Arno]

I agree with you,diet and the environment are two things that can cause changes in shell colour.

[Dusk]

kanin - that's really interesting - high calcium causing paler shells. I wonder if that would be consistent across snail species?