Aloha,
A true melanistic cowry has dorsal pygmentation soo dark as to obscure the
original color & pattern on a mollusk in it's adult stage. Besides the
melanistic cowries of New Caledonia there are other examples. Australian
Zoila like thersites & friendii occur near black or totally black & are
often reffered as near or totally melanistic.

In the Indo-Pacific mauritiana do occur near or totally dark by 3 stimuli.
1)Specimens near or on iron-rich habitats, like shipwrecks, are near or
totally dark red. This is commonly seen in stercoraria from Africa. Also
arabica & eglantina.
2)Extreme damage induced by nature can & does alter shape & coloration. This
is more predominant when a cowry is in the juvenile stage.
3)Chemical leaching. Many experts feel that nickel mining in New Caledonia
is the cause for melanism & rostration. Other Indo-Pacific economies rely on
strip mining for tin, like in the Philippines, which also can be a local
cause for abnormalities.

In this case the pix of the questionable Tiger is the focus of this thread.
If you view the pix you can see it isn't melanistic.   Mahalo!  CHRIS:)

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