Of Sundials and Murex

by Peggy Williams

On a recent trip to West Mexico I reconfirmed a couple of previous observations.

Reading shell books, I had heard that some species of Architectonicidae live among sea anemones - the kind that grrow so closely together that they form a mat (called "mat anemones" and in the genus Zoanthus at least in the Caribbean). Several years ago, at an island off La Paz, Baja California Sur, I happened to be at the right place at the right time: just as the tide was coming back in after an exceptional low. I happened on an area of mat anemones and there were sundials - Heliacus bicanaliculatus (Valenciennes, 1832) just emerging from their "nap" during low tide down among the anemones.They came up

on their sides, having been spire-side down while resting, then turned spire-side up. In an area about three feet square, we found over 70 of them!

On later trips to Baja I hunted out mat anemones and have always been able to find a few Heliacus each time, including this year's trip. Never have I had such a bounty as the first time, however.

I've looked in the Caribbean as well, but never until last year found living Heliacus. This time was in Brazil, in Salvador, at a rocky headland. The mat anemones were covering the rocks at lowest tide line, and I found not one, but two species of Arcitectonica: the cognate of bicanaiculatus, Heliacus cylindricus (Gmelin, 1791) and Heliacus perrieri (Rochebrune, 1881). As a bonus, hiding among the mat anemones were several Coralliophila aberrans (C B Adams, 1850).

The operculum of the Heliacus is unique, thick and pyramid-shaped on the outside and hooked on the inside. One of the shellers thought it was a crab!

Also from reading shell books, I know that many species of Muricidae gather together to lay eggs. I've seen many Muricanthus nigritus (Philippi, 1845) with another individual's purple egg cases attached to them. At Bahia Concepción in Baja I have several times found egg masses blown high on shore and pulled them apart to reveal several Haustellum ruthae Vokes, 1988, dead within the egg cases, complete with opercula. On one trip, nine of us pulled at a yard-across egg mass to our heart's

Two Heliacus on mat anemones. Note the pointed operculum protruding from the mouth of the one at the top.


content, finding over 300 shells (I myself had 49), and we left one of our number happily pulling out even more when the rest of us tired of it!

Only once have I found such an egg mass in the Caribbean, on Margarita Island in Venezuela, and I found one Haustellum chrysostoma (Sowerby, 1834) within it. However, I was able to witness an egg-laying frenzy of Haustellum messorius (Sowerby, 1834) in Belize while snorkeling in a quiet lagoon. Animals were gathering from all compass points to add their eggs to the growing mass, already about nine inches across, with about six of them actively laying at the time. I left most of the shells there, taking only a few that were crawling away after laying.

Article and photos copyright Peggy Williams. This article may be used in shell club publications with attribution to Peggy Williams, www.Shelltrips.com.