Molluscan Reproduction and Egg Case

Molluscan Reproduction and Egg Case (HM20DR)

Location: Sanibel, FL 33957 Lee County
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Country: United States of America
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N 26° 27.168', W 82° 0.873'

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Do you know how mollusk babies are born? Sexes are separate in most mollusks, but some will have both sexes in the same individual (hermaphrodites).

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 lighting 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.

How many different types of egg cased can you find?

A banded tulip, Fasciolaria ilium hunteria, lay an egg case.
Photo by Amy Tripp

A crown conch,
Melongena corona, and her egg cases.
Photo by Jose 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 angel Vaddes

The egg chain of the lighting whelk, Busycon sinistrum. The egg chain may bear form 50 to 180 cases, and each case may hold from 20 to 200 embryos.
Photo by Jose H. Leal

Egg cases of the many-whorled cantharus, Cantharus multangulus.
Photo by Jose H. Leal

Large communal spawn of apple murexes, Chicoreus pomum.
Photo by Amy Tripp

A female lighting whelk, Busycon sinistrum, surrounded by males. (Male always small)
Photo by Amy Tripp

The delicate eggs cases of the sharp rib drill, Eupleura sulcidentata, look like-tiny champagne goblets.
Photo by Jose H. Leal

Striped false limpets, Siphonaria pectinate, lay tiny eggs (insert) in the spring.
Photo by Jose H. Leal

Content and Design by:

The Bailey - Matthews Shell Museum
HM NumberHM20DR
Marker ConditionNo reports yet
Date Added Thursday, August 3rd, 2017 at 1:03pm PDT -07:00
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Locationbig map
UTM (WGS84 Datum)17J E 398855 N 7073770
Decimal Degrees26.45280000, -82.01455000
Degrees and Decimal MinutesN 26° 27.168', W 82° 0.873'
Degrees, Minutes and Seconds26° 27' 10.0800" N, 82° 0' 52.3800" W
Driving DirectionsGoogle Maps
Area Code(s)239
Closest Postal AddressAt or near 110 Periwinkle Way, Sanibel FL 33957, US
Alternative Maps Google Maps, MapQuest, Bing Maps, Yahoo Maps, MSR Maps, OpenCycleMap, MyTopo Maps, OpenStreetMap

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