Attractive
Horns Aplenty -
But Full of Flukes
"Horn of Plenty" or plenty of horns. These are in many ways similar but also different. The horn of plenty is a legendary ram's horn that abounded with fruits and produce of all kinds. Not too believable a story, but it has come to symbolize the "good life." However, can life be any better than it is for a snail that has such an ideal habitat that is found in almost unbelievable numbers? Ah yes, the soft mud and gloop of California's estuaries IS the good life, at least it is for the plentiful California horn snail. Yet as good as the life has proved to be for this 1 1/4 inch-long snail, its success story is also one that is full of interesting oddities, even genuine flukes.
The California horn snail is a member of the horn shell family, or Potomodiae. The first part of its scientific name (Cerithidea california) is "cerith" or Greek for horn. That seems logical enough, for the shell does resemble a miniature ram's horn and called in English "horn." But through a fluke in other snails, some (although related) snails are placed in the family Cerithiidae, yet these are typically referred to, not as horn snails, but as Ceriths.
True horn shells, or again, those in the family Potamidae, are primarily found in tropical waters. California's species, which ranges from Baja to Marin County, is an exception. Sure, some tropical families will have an occasionally renegade member that will venture into California's non-tropical seas when El Niño warms things up a bit, or through some other fluke in weather patterns; however, the California horn snail is no accidental part of the state's marine scene. Far from it - its niche in the muddy bays is so firmly established that no other animal can come close to it in its numbers. On some sections of mud flats, especially under the cover of old boards or near rocks, hundreds of this type of snail will huddle together.
After all, this is an ideal home for this snail. It feeds on decayed organic matter (or detritus) and films of diatoms on the mud. It is quite hardy, too. It doesn't mind being inundated with some fresh water, and it also is able to stand days on end out of the water (although under these latter circumstances, it will usually close itself up tight so as to avoid dehydration).
Yet,
as rough and tough of an environment in which it lives, the
California horn snail actually has one of the prettiest little shells
found along the west coast. It is typically a chocolate brown
(ranging from light "milk chocolate" to almost black "semi-sweet"),
with about 10 to 12 distinct spirals on its gracefully slender
spiral. It is not glossy smooth, but almost cross-hatched in
appearance, with every so often a lighter colored varix (or a thicker
bump where the snail took a rest in its shell growing process). No
wonder beachcombers who frequent California's seashore find the
California horn snail to be so attractive, even when it is just a
dead, worn shell in the beach wash, far from where it once lived.
This shell often finds its way into "beach art" and shell jewelry.
But the California horn snail's idyllic life as "number one snail of the mud flat" came to the end a few decades ago by some other "mindless creatures." When the Japanese oyster (Crassostrea gigas) was introduced in northern bays, other "non-invited" species were inadvertently brought in as well and found California's mud flat environment to be to their liking.
One of these is the zoned horn snail (Batillaria attramentaria), a Japanese import, first noticed in California in the mid-thirties. It is closely related to the California horn snail, even being similar in size, appearance, and habits. It does, however, lack the attractive ribbing on its shell. Although it ecologically and biologically has the potential of seriously competing with the California horn snail, it so far has tended to stay north, with the native snail south, and only in the central part of the state do these "twain meet." Some sources even call the exotic zoned horn snail a "neutral immigrant."
Not so the unrelated eastern mud snail Nassarius obsoletus). It has virtually usurped the San Francisco Bay from the California horn snail. It is quite omnivorous and seemed to have "hitchhiked" on the Virginia oyster (C. inica) from the Atlantic.
Such
are some of the "flukes" that have happened in the life of the
California horn snail in the early days of aquaculture, before things
were so strictly controlled. Yet in another way, the California horn
sail is a snail whose life has always been full of flukes - real
flukes, as in trematode worm flukes.
Many of the parasitic trematodes (or flukes) infest marine animals and they use marine snails as their intermediate hosts, with their final hosts being marine fishes and shore birds. Fortunately, for people who explore the ocean, almost all of the harmful flukes - and some of these are really nasty - that infest humans use fresh water, and not salt water snails, as their intermediaries.
But happily, no fluke even that bad is to be found in parasitizing the California horn snail - but over two dozen other types do. They are considered to be harmless, even to the birds and fishes they eventually infest. The zoned horn snail has its own flukes as well. When the infestation of worms becomes too extensive, they can hamper the snails' ability to reproduce.
The Horn of Plenty - that stylized ram's horn overflowing with a tremendous assortment of luscious fruit may seem to be an apt symbol to many of the "good life." But on California's lush, rich mud flats, what more appropriate symbol could there be than the plentiful horn snail, with its own attractive shell overflowing with an assortment of trematode worms. Ah, the good life indeed!