#wentletrap

Precious Wentletrap aka Staircase Shell (Epitonium scalare), family Epitoniidae, Exmouth Gulf, Western Australia

Marine snail.

Painted Wentletrap Epitonium tinctum

Found in the Eastern Pacific from southern Alaska to Mexico. At high tide (twice a day) it feeds on the tips of anemone tentacles; then at low tide burrows into the sand. Living wentletraps contain a purple, toxic dye. The dye appears to be an anesthetic and it is thought that the snail may use it to relax the anemone tissues before feeding.

Originally described as Turbo scalaris, and renamed and synonymised repeatedly over the centuries since. The family-level taxonomy has been even worse, if anything. Epitonium means 'turncock' and scalare's meanings include 'ladder' or 'staircase'. Wentletrap is from the Dutch for spiral staircase.

Found in subtidal sandy areas from Red Sea, the coasts of the Indian Ocean, the South West Pacific Ocean and among the Fiji Islands and Japan. Predators/parasites of sea anemones and corals, that they devour in small bits at a time.

A very pretty shell - the whorls are only connected to each other by the ribs every few millimeters. In the 1600s and 1700s they were considered a very rare shell and specimens changed hands for large sums of money. For example, about 1750, the Holy Roman Emperor Francis I paid 4,000 guilders for a specimen. Since the Dutch controlled the areas where the shells were thought to be found, they made sure to extract every duit they could from rich collectors.

'Dilated lyre-shaped vein hole', refering to the shape of the ribs on the shell.

Another one described by Zittel, in 1864, but he described it as Scalaria lyrata. Synonyms include Scalaria browni, S. rugulosa, S. rugulosa lyrata; Epitonium (Cirsotrema) rugulosum lyratum; E. (Cirsotrema) lyratum; and Cirsotrema browni.

Unusually large for a Wentletrap, sometimes exceeding 8cm. Unlike the vast majority of gastropods, the shells of Cirsotrema (and of some other epitoniids) are made of calcite, and can survive in fossil deposits where shells made of aragonite have long since dissolved.

Definitely found in rocks dating from 35 to 26 million years of age, but possibly from a much wider age range.

Little is known about the biology of living wentletraps (from the Dutch for spiral staircase) - they're believed to be specialist predators and parasites of sea anemones and corals.