Molluscan Egg Cases
| The non-Busycon
egg mass Nancy described, as I picture it, is probably from a Fasciolariid,
either Fasciolaria tulipa or Pleuroploca gigantea. If it is football-sized,
I would lean toward Pleuroploca. Also, the sides of the individual capsules
of Fasciolaria are smooth, while those of Pleuroploca have a series of
encircling ridges. The masses of capsules are pretty impressive looking,
but there really isn't much substance to them. If the mass is already
hatched out, and you dry it, it weighs almost nothing. So a football-size
mass really requires the secretion of only a few ounces of capsule material.
If the capsules have not hatched out before the mass is beached, then
each capsule probably contains many embryonic shells, which add to the
weight. If it "rattles" after drying, it probably contains shells.
Break open a capsule and see. The capsules are made of a secreted proteinaceous
substance either identical to or similar to conchiolin, which opercula
are made of (and which is, as you observed, a very strong substance).
It is somewhat similar to the material of human fingernails. Each string
(of Busycon capsules) is the work of a single animal. Some northern species
like Neptunea decemcostata sometimes do produce "communal" clumps,
containing capsules from several individuals. I don't know if any southern
species do this. The individual capsules are formed one at a time, and
the string gradually grows longer (or the clump larger) as each capsule
is added.
Paul M. |
| This web page
gives a bit of information on the formation of the casings: http://www.arches.uga.edu/~amylyne/GSC/whelk.html
|
| Several murex
species produce communal clumps, and Haustellum ruthae lay so many that
many of the parents end up inside the egg mass and die there. We once
found an egg mass over a yard across with at least 400 shells entombed
in it.
Solenostira also lay eggs together and atop each other. Peggy |
|
Please use back button to return to your page
|
OR
|