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Limpets

Volcano Limpet on rock
Shell of a Volcano Limpet Shell of a Volcano Limpet

Volcano Limpet ( Fissurella volcano )

Volcano Limpets are easily identified by a small hole in the top of the shell. They are typically an inch or less in size and found in the mid intertidal zones. The color of the shell ranges from light brown to red with and have small ridges on the shell. This Limpet can be confused with juvenile giant key whole limpets as they also have a small hole on the top of the shell.
Owl Limpet on rock
Limpet on exposed rock. Notice the open area where the limpet will graze. Single Owl Limpet in its home range. Owl limpets will graze a certain area Owl Limpet covered with algae Owl Limpet covered with buckshot barnacles Owl Limpet

Owl Limpet ( Lottia gigantea )

These limpets are one of the more common types of Limpets a visitor will see. They frequent the mid and upper tidal zones. They are commonly seen in large bare patches of rock where they will graze on algae. The shell color is light to medium brown and the shell is generally smooth. Larger Owl limpets frequently have other Limpets and barnacles attached to their shells.
Owl Limpet on rock
Limpet on exposed rock. Notice the open area where the limpet will graze. Single Owl Limpet in its home range. Owl limpets will graze a certain area

Rough Limpet ( Macklintockia scabra )

Rough Limpets are small limpets that are generally less than an inch in diameter. They are characterized by having ridges that radiate from the top of the cone out to the edges. The ridges are deep and obvious. Other limpets have ridges but not as deep as the Rough limpets. Rough Limpets range from light brown to darker brown and several other colors ranging on location.
Giant Keyhole Limpet exposed at low tide
Shell of a Giant Keyhole Limpet Giant Keyhole Limpet with mantle covering entire shell

Giant Keyhole Limpet ( Megathura crenulata )

The adult giant keyhole limpet is easily identified by its large shell with a single hole on the top of the shell. The shell is typically between 3-5 inches for an adult. These limpets are usually seen with a fleshy mantle that covers the upper part of the shell unlike any other limpet. This fleshy mantle is generally very dark in color.
Various limpets on rocks
Various limpets and buckshot barnacles Various limpets on rocks Various limpets on rocks Limpets will live in depressions in rocks Various limpets on rocks Note white limpet on the gooseneck barancle Various limpets on rocks

Finger/File/Checkered Limpets ( Lottia sp )

Limpets in this group are on the smaller side usually about an inch or less in diameter. The color of the shell ranges from brown, green, grey and reddish brown. These limpets are harder to identify as they are quite similar in both appearance and ecology.

Limpets

Description – Limpets are part of the mollusk family and related to snails. Like snails, they have a fleshy foot that is used to hold onto rocks and move around. Limpets have a single flat or cone shaped shell on the top of their bodies. The color of the shells ranges from light browns to darker browns and greens. Limpets range in size from less than an inch to over several inches in length for larger species. There are many different species of Limpets that live in the tidepool areas. Listed below are some of the more common species.

Feeding – Limpets will feed on a variety of algae. Some limpets eat the small microscopic algae that cover intertidal rock surfaces while other feed on larger algae. Volcano limpets for example feed on the red colored coralline algae. Finger limpets prefer microscopic algae and diatoms while the Shield limpet prefers larger macro algae.

Protection – The primary predator for Limpets are Sea Stars, birds and the occasional crab. Limpets will clamp down tightly on the rocks when threatened. Limpets will also clamp down on rocks when exposed to high tide to prevent drying out. They use a mucus layer to create an air tight seal around the shell and the rock surface.

Ecology - Limpets will slowly move around grazing the exposed rock surfaces. Like snails, they use a part of their mouth ( radula ) to scrape off the algae. Limpets usually are more active when submerged and move much less when exposed to air during low tide. Some Limpets are will also “farm” an area of rock. This is where the limpet will graze a certain area of rock and remove other invaders including other limpets. They then continue to feed on the algae in one area while letting the algae grow on other areas. Owl limpets are good examples of this behavior.

Some limpets also have a home scar. This is a place in the rock surface where they return each day after feeding before low tide. The benefit is thought to be that the indentation in rock surface will form a more tighter seal when the Limpet is exposed to air during lower tides.
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