Most snails, by necessity, travel at a snail's pace. But how fast can anyone expect animals to go when they have been classified in the Class Gastropoda or "stomach foot"?
However, there are some snails that don't have to spend their entire lives stuck to a rock - - or buried in the mud, or in some other way attached to something fairly solid. They can glide, swim or float about in the water. And while not all of these go much faster than a snail's pace, there are a few that are able to travel as fast as the wind.
Heavy
shells are a hindrance to any snail being able to swim. If an
abalone, for example, has its "stomach-foot" dislodged from a rock
(of course, this usually isn't done by accident, but there is likely
a dull metal object involved in the process), it cannot swim away
with any graceful flapping motion. No, it will sink like a rock
(unless its fall is conveniently intercepted by the hand of the diver
who also manipulated the ab iron).
Nudibranchs and other sea slugs are not weighted down by any heavy shell, and many of them are able to swim a bit if they become detached from their habitat. Several California species can thus be seen "taking a few strokes" en route to a new location. The Spanish shawl nudibranch (Flabellinopsis iodenea) flip-flops its whole body back and forth. The Pacific wingfoot snail (Gastropteron pacificum), although at times presented as a full-time swimmer, just periodically glides over deep water mud. If a lion's mane nudibranch (Melibe leonina) gets really upset, not only will it swim away by flexing its body, but its broad leaf-like cerata will break off like a lizard's tail and take off on it's own. Additionally, this "stomach-foot" has been known to gulp air with its oversized hood to further assist it to stay afloat. But all of these are only occasional swimmers, and as soon as they can they return to their snail's pace pacing.
Not
so with blue glaucus (Glaucus atlanticus). It takes the lion's mane's
trick of a gulp of air to perfection and lives its entire life
floating about the high seas, buoyed up with a gut full of air. And
the totally pelagic blue glaucus does this all upside-down, right
under the surface of the water. It survives by eating other floating
animals, particularly Portuguese-men-of-war and by-the-wind-sailors.
Another nudibranch, Fiona pinnata, also dines on those high-sea floaters whenever it can. However, Fiona has a slight disadvantage in reaching that goal. This species is considered to be pelagic, yet it cannot swim! But it's a great rafter and will hitch a ride on whatever it can, be that driftwood, floating barnacles, or on another pelagic snail, the violet snail or Janthina janthina.
One
of the prettiest snails of the neuston (or the animals that float on
the surface of the ocean), Janthina is not shell-less like many of
its "neighbors" but has a thin, delicate purple shell. However, even
that would sink if Janthina did not produce its own bubble float.
This snail is also a man-of-war and by-the-wind-sailor eater, and
seems to use a special purple dye to anesthetize the powerful
stinging cells of its prey.
But the best swimmers among pelagic snails don't look like gastopods at all. These are pteropods or "wing-footed." They have long tapering bodies - - either "shelled" or "naked" - - and a pair of paddle-like wing-feet. Some of these paddle feet are so big that they have earned them the common name "sea butterflies." Nevertheless, they are still considered to be closely related to nudibranchs. Shelled pteropods (Order Thecosomata) do not really have true shells but an internal transparent pseudoconch (or "false shell.") They come to the surface of the ocean at night to feed on small plankton and return to the depths during the day. The naked pteropods (Order Gymnosomata) display an opposite pattern of migration and are more voracious predators, even feeding on their slower swimming "shelled cousins."
Another
pelagic snail is the glassy nautilus (Carinaria cristata). In some
ways it looks like a pteropod but is in another, even more obscure
gastropod group, the heteropods, or "different foot" - - and its foot
sure is different. Like Glaucus it lives upside down, but it doesn't
use its foot to toot around on the ocean's surface tension. Instead
its "different foot," just a large blob on top, is a functional fin.
Its body is enormous compared to its shell, which dangles below like
a keel on a ship.
Back
in the 1800s, when shell collecting was in a real heyday among the
high society of Europe, the odd shell of Carinaria was considered to
be one of the most prized shells around. Certainly, it does have its
own unique beauty, resembling fine, delicate crystal (although the
shell only reaches about three inches in length). But it is
especially coveted because there were only a few individual shells
around, and no one had figured out exactly what animal produced them.
Pelagic snails can potentially be found in all temperate and tropical seas of the world, including off of California. Some of the ones so far described have been beached often enough that basic seashore guides feel justified in including them in their listing of the state's marine life. But just when and where these animals might appear is totally unpredictable. It's just whenever, wherever, and however the winds of chance happen to bring ashore these snails that travel with the wind.
Nancy Vander Velde is a frequent contributor to
California Diving News. She has also illustrated several books.
Drawings by Nancy Vander Velde.