Word of the Month: Trochus

David Zapatka

While cruising around Australia on the way to Thursday Island, I read this description about the port city. “The mixed population of Malays, Chinese, Japanese, and Melanesians are engaged mainly in pearling and trochus and sea cucumber fishing.”

Trochus—tro·​chus noun: 1.a. Capitalized. a genus of chiefly Old World tropical marine gastropods (family Trochidae) with beautifully nacreous bluntly conical shells including a large Indo-Pacific species (T. niloticus) extensively used in making buttons, beads, ornamental objects, and home décor. 1.b. plural -es : top shell.

2. the inner preoral band of cilia of a trochal disc.

Origin and Etymology—New Latin, from Latin, wheel, iron hoop, from Greek trochos wheel.

First Use—The name Trochus, was used for the first time by Guillaume Rondelet, in 1558, who assembled under this title a rather miscellaneous assortment of univalves. Linnaeus‘ genus Trochus is composed principally of true Trochidae, but it is now viewed as having contained species of several other very different families.

Growing naturally on isolated atoll reefs throughout the Indo-Pacific oceans, these sea snails have large, thick, solid shells that have a broadly conical spire and a flat to convex base. The periphery is angulated. The outer and basal lips are smooth within. The columella has a strong fold above, ending in an obtuse tooth below. The interior of the shell is pearly and iridescent because of a thick layer of nacre (mother of pearl). The exterior is camouflaged allowing it to blend into the bright coral it grows alongside.

Aside from its shell being exported to developed countries, the trochus meat is edible and cooked, dried or canned occasionally for consumption. It is estimated that 80% of the trochus harvest in the South Pacific are taken for subsistence purposes.

Trochus snails have an average lifespan of 2-3 years.

Trochus used in a sentence:

Trochus are rough, conical, pointed shells (resembling a witch’s hat) found around the northern coast, from Karratha to Mackay, on exposed intertidal and subtidal areas of coral reefs.

Trochus is valued for its meat and its shell, which is used to make buttons, jewelry, and handicrafts.

In countries such as Fiji, Vanuatu, Solomon Islands, and Papua New Guinea, there are factories that process trochus shells for export, handling around 100 to 200 tons annually.

In recent decades, the community at One Arm Point has sold the trochus shell into overseas markets, where it’s used to make buttons for the high-end fashion scene of Europe.

Children are fascinated with trochus shells and they can be used as part of marine teaching or admired at home.

Have you seen one of these beautiful trochus shells? Please submit your experiences or any word you may like to share along with your insights and comments to [email protected].