LIMPETS
Walking some beaches when the tide is out, one can often find attached to exposed rocks and big boulders, and in rock crevices, a populace of marine hangers-on -- creatures related to snails and nudibranchs -- creatures called limpets.
Tectura persona Photo by Mary Jo Adams Copyright 2004 |
Most species seen along our shores are 1/4 - 2" in size when mature. In their attached mode, or as empty conica or cap-shaped shells, some limpet species have been likened in looks to mini-volcanoes or woven Chinese hats. One species, even though not considered a "true limpet", has a hole in its top. Most often grayish-brown to brown, they tend to blend in nicely with their rock surroundings, although there is a variation in color pattern as well as size and shape. |
Univalves, each limpet is attached to its rock home or other surface by its large broad foot which is the same generally ovalish shape as its protective shell. Having no operculum or such means of closing the shell, the shell-shaped foot acts as a suction cup -- squeezing excess water out and creating a suction that can reach 70-80 lbs psi. It's a suction so strong that a moist watertight chamber is created on its home base - its substrate - one that seals out the drying effects of the sun's rays and |
Tectura persona Photo by Mary Jo Adams Copyright 2004 |
air. A seal so tight that it can be difficult to pull a limpet loose from its anchorage without breaking the shell.
Between the shell and suction-created
seal, the inhabitant is also able to pretty successfully protect
itself from harsh wave action and predators. About the only predators
that can pry off attached limpets are our red-billed, multi-tooled
Black Oystercatchers and sea stars, the latter of which will patiently
pull long periods of time until the strong suction is finally compromised.
Limpets, remember, are mollusks -- therefore closely related to
mussels and periwinkles -- members of the most diverse and successful
of all salt-water invertebrate phyla.
They are also herbivores. When the sun retreats from the western
horizon and darkness descends, and water covers them at night, one
species I often see, Tectura persona, extend a muscular foot and
begin travelling -- begin slowly moving about, seeking foodstuffs
such as diatoms and the algal and other encrusted debris on rocks
within about three feet of their chosen homesites. Such vittles
the T. persona busily scrape off with their long rasplike tongues
or radula.
Roaming, browsing, dining-time over, they return -- creep slowly
back to their original well scraped rock home-sites -- small depressions
called limpet scars. Just how they are able to return to these
sites without retracing their initial route-about is not completely
understood -- one of the sea's secrets. But once back, it's
time to hunker down -- clamp down -- create again those water-tight
quarters.
Tectura persona are rather
large limpets, as limpets go 1-1 1/2" long -- and also rather handsome
ones. They are found on bouldery beaches on the lower portions
and edges of big rocks -- about where the rocks meet the sand or
mud.
Commonly referred to as a Speckled Limpet, Tectura persona 's apex
is slightly behind the somewhat inflated appearing shell's center,
and has many small white dots or speckles on its brownish upper
shell -- a larger pattern of brown and white markings forming a
band at the bottom of the shell.
Turn the shell over -- gaze within -- and a lovely shiny opaque-white
to gray-blue interior is revealed with a chocolate brown Rorschach
inkblot-like design at the bottom. It's a shell thats a looker
both inside and out.
Are limpets a sought after food source, you may ask. Not long
ago some hikers told me they indeed do seek them out when camping
by a beach. And the same was true of coastal Native American
groups for generations -- and far-removed Pacific Island peoples
as well.
Limpets. Fascinating, mostly sea-dwelling creatures out there
working at making a living, as so many other life forms do, in our
Sound waters