Sanibel Island in Lee County, Florida — The American South (South Atlantic)
Molluscan Reproduction and Egg Case
Photographed by Sandra Hughes, October 11, 2015
1. Molluscan Reproduction and Egg Case Marker
In other cases, such as in quahog clams and slipper snails, the mollusk undergoes sex reversal, with individual starting their lives as males and changing into females as they grow older.
In many mollusk species, male and female will release sperm and eggs in the water. Sperm will fertilize eggs, which become free-swimming larvae. This is the case of clams, oysters, limpets, and turban snails, to name a few. In other mollusk groups, the male will fertilize the female by depositing sperm into the female reproductive organ. The female later will deposit eggs on the sea floor.
Sanibel beaches are famous for the largest variety of egg cases that wash ashore after storms.
Some of these are illustrated in this panel. One of the most commonly found is the egg case chain of the lightning whelk, which could measure up to 4 feet in length.
A female whelk may spend more than a week laying the egg case chain, which she attaches to a pebble or shell buried in the sand.
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A banded tulip, Fasciolaria ilium hunteria, laying an egg case.
Photo by Amy Tripp.
A crown conch, Melongena corona, and her egg cases.
Photo by Josι H. Leal.
A horse conch, Triplofusus giantess, and her egg cases.
Photo by Amy Tripp.
Antilles glassy bubble, Haminoea antillarum, and egg ribbon.
Photo by Αngel Valdes.
The egg chain of the lightning whelk, Busycon sinistrum.
The egg chain may bear from 50 to 180 cases, and each case may hold from 20 to 200 embryos.
Photo by Josι H. Leal.
Egg cases of the many-whorled cantharus, Cantharus multangulus.
Photo by Josι H. Leal.
Large communal spawn of apple murexes, Chicoreus pomum.
Photo by Amy Tripp.
A female lightning whelk, Busycon sinistrum, surrounded by males. (Male are always small)
Photo by Amy Tripp.
The delicate eggs cases of the sharp rib drill, Eupleura sulcidentata, look like tiny champagne goblets.
Photo by Josι H. Leal.
Striped false limpets, Siphonaria pectinate, lay tiny eggs (insert) in the spring.
Photo by Josι H. Leal.
Content and Design by:
The Bailey - Matthews Shell
Photographed by Sandra Hughes, October 11, 2015
2. Shells of Sanibel and Captiva Islands
Topics. This historical marker is listed in these topic lists: Animals • Environment.
Location. 26° 27.168′ N, 82° 0.873′ W. Marker is on Sanibel Island, Florida, in Lee County. It is on Periwinkle Way. Marker is located Sanibel Lighthouse Beach Park. Touch for map. Marker is at or near this postal address: 110/153 Perwinkle Way, Sanibel FL 33957, United States of America. Touch for directions.
Regionally, this marker is on Florida’s Gulf Coast. It is also in the American South and on the Gulf Coast. Globally, it is in the North Atlantic Region, North America, a Gulf of Mexico state, the Western Hemisphere, the Western World, and the Anglosphere. Historically, it finds itself in what was once New Spain, the territory of the Mississippian Culture, one of the Confederate States of America, and the Antebellum South.
Other nearby markers. At least 8 other markers are within 4 miles of this marker, measured as the crow flies: Sanibel & Everglades Restoration (here, next to this marker); The Beach is a wild place (a few steps from this marker); Mollusks and the Environment (a few steps from this marker); Sea Turtles on Sanibel (a few steps from this marker); Sanibel Lighthouse (within shouting distance of this marker); Nature's Landlord (within shouting distance of this marker); Community (approx. 3.7 miles away); Recreation (approx. 3.8 miles away). Touch for a list and map of all markers in Sanibel Island.
Also see . . .
1. Banded Tulip. Banded Tulip Fasciolaria hunteria Common in shallow grassy bays. Harder to find along the beach as it likes the grass flats that are in the bay. Up to 3" (Submitted on July 29, 2017, by Sandra Hughes Tidwell of Killen, Alabama, USA.)
2. Haminoea antillarum (dOrbigny, 1841) Antilles Glassy-bubble. Lake Worth Lagoon, Palm Beach Inlet, Palm Beach County, Florida, 1/16/2013. Photographed by Anne DuPont. (Submitted on July 29, 2017, by Sandra Hughes Tidwell of Killen, Alabama, USA.)
3. Apple Murex Shells. Phyllonotus pomum One of the more common murex that can be found along the shore. Is often occupied by hermit crabs. Up to 3" (Submitted on July 29, 2017, by Sandra Hughes Tidwell of Killen, Alabama, USA.)
4. Lightning Whelk (Busycon perversum pulley). Like snails, the lightning whelk is in the class Gastropoda which means "stomach footed". Gastropods are univalves (have only one shell). Hermit crabs often make homes of unoccupied lightning whelk shells. A lightning whelk leaves behind a trail when crawling. It is often easy to track them. The shell grows very quickly when the whelk is young as long as food is abundant. As it gets older, the shell grows more slowly. The color of the shell depends greatly on light, temperature and age. Older whelks have pale shells. (Submitted on July 29, 2017, by Sandra Hughes Tidwell of Killen, Alabama, USA.)
5. Triplofusus giganteus (Kiener, 1840) Horse Conch Egg Mass. Embryonic specimens extracted from egg mass pictured above (Submitted on July 29, 2017, by Sandra Hughes Tidwell of Killen, Alabama, USA.)
Credits. This page was last revised on January 9, 2025. It was originally submitted on July 29, 2017, by Sandra Hughes Tidwell of Killen, Alabama, USA. This page has been viewed 750 times since then and 33 times this year. Photos: 1, 2. submitted on July 29, 2017, by Sandra Hughes Tidwell of Killen, Alabama, USA. • Bill Pfingsten was the editor who published this page.
