Tag Archives: Amastra humilis

Amastra humilis ssp. moomomiensis Pilsbry & Cooke

Moomomi Amastra Snail (Amastra humilis ssp. moomomiensis)

The Mo’omomi beach at the northwestern coast of Moloka’i, Hawaiian Islands, is one of the last remaining dune sides found on these islands; thousands of shells poke out of the sandstone cliffs near the beach, some bleached completely, some still bearing hints of their former coloration; these are the shells of land snails that formerly inhabited this now quite desert-like place.

In the Pleistocene, the climate of the Hawaiian Islands was much wetter than it is today and the area that is now covered by sand dunes was forested back then. When the climate became dryer at the beginning of the Holocene about 10000 BP., these forests disappeared, leading to the extinction of the local snail populations.

In fact, the shells can be dated to ages from 42000 to about 3000 years, which means that this form died out during the Holocene, and, that this is a case of a natural extinction.

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Depiction from: ‘George W. Tryon; Henry A. Pilsbry; a.o.: Manual of Conchology. Second series: Pulmonata. Vol 23: Appendix to Amastridae. Tornatellinidae. Index, vols. XXI-XXIII. 1915-1916

(public domain)

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edited: 31.10.2020