Invertebrates Active day and night

Plate Limpet

Lottia scutum

iNaturalist Wikipedia

The Plate Limpet is the unsung architect of the rocky shoreline, a master of suction that navigates the turbulent Pacific tides with surprising grace.

0 Sightings

0 Habitats

Quick Identification

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Size

30-60 mm (1.2-2.4 inches) in length; height is typically 1/3 of the length

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Colors

Mottled greenish-gray, brown, or off-white; interior is bluish-white with a dark brown owl-shaped central scar

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Key Features

Flattened, plate-like oval shell
Fine radiating ribs often worn smooth
Large, dark brown apical stain on the interior
Tentacles are typically white or pale

When You’ll See Them

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Activity pattern Active day and night

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Peak hours Most active during high tide and nocturnal low tides

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Season Year-round

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Diet Herbivorous grazer; uses a radula to scrape microfilm algae, diatoms, and tiny seaweed spores from rocky surfaces.

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Habitat Intertidal rocky shores, specifically the mid-to-low tide zones and tide pools.

public Geographic range

Where Does the Plate Limpet Live?

The Plate Limpet is a staple of the North Pacific coastline, stretching its native range from the Aleutian Islands in Alaska down through the coastal waters of British Columbia and the United States to northern Baja California, Mexico. This species thrives in the nutrient-rich, cold waters of the Pacific, where rocky outcroppings provide the stable substrate necessary for their survival. While primarily found along the mainland coast, they also inhabit various offshore islands within this temperate marine corridor.

Basemap © OpenStreetMap contributors

3 Countries

1.2M km² Range

Least Concern Conservation

US United States

Marginal

CA Canada

Marginal

MX Mexico

Marginal

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iNaturalist / Verified observation data

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Behavior

The Plate Limpet is a fascinating intertidal resident known for its "homing" behavior, though it is less strictly tied to a single spot than other limpet species. During high tide or at night, it crawls across rocky surfaces to graze, using a specialized tongue-like organ called a radula to scrape microscopic algae and diatoms from the rock. As the tide recedes, it returns to a preferred resting spot where its shell fits the rock's contours perfectly, creating a seal that prevents desiccation.

Unlike many other mollusks, the Plate Limpet is quite active when submerged. It has evolved a low-profile, hydrodynamic shape that allows it to withstand the incredible force of crashing waves. While they appear sedentary to the casual observer, time-lapse photography reveals a creature that is constantly navigating its miniature mountain range of barnacles and seaweed in search of food.

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Camera Tips

Capturing the Plate Limpet on camera requires a specialized approach since they inhabit the splash zone. Use a waterproof action camera with a dedicated macro lens or a high-quality underwater housing. Because limpets move very slowly, traditional video is often boring; instead, set your camera to time-lapse mode. Taking one frame every 30 to 60 seconds over a full tide cycle will reveal their complex grazing patterns and social interactions with other limpets.

Mount your camera as low as possible. A "gorilla-pod" or a weighted beanbag base works well for stabilizing the camera on uneven, slippery rocks. Position the lens just a few inches from a cluster of limpets during low tide, ensuring the camera is secure enough to withstand the incoming surge. Side-lighting from a waterproof LED can help highlight the texture of their shells and the movement of their muscular foot when they lift slightly to move.

Pay attention to the tide charts. The best footage is usually captured just as the tide begins to cover the rocks, as this is when the Plate Limpet "wakes up" and begins to forage. If you are filming in a tide pool, ensure the water is still and clear; using a circular polarizer filter can help cut through the surface reflection if the camera is positioned above the waterline. Be sure to rinse all your equipment in fresh water immediately after use to prevent salt corrosion.

Similar Species

Species that look similar or are commonly confused with Plate Limpet.

Shield Limpet

The Shield Limpet has a higher, more conical shell with stronger ribs and a different internal color pattern.

Ribbed Limpet

Ribbed Limpets are smaller, have much deeper ridges, and are usually found much higher up on the rocks near the high-tide line.

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Frequently Asked Questions

Plate Limpet are most active when they are submerged by the tide, regardless of whether it is day or night. However, they tend to move more extensively during nocturnal high tides when the risk of predation from birds like oystercatchers is lower.

Since Plate Limpet are marine animals, you can only 'attract' them if your backyard includes a rocky ocean shoreline. Maintaining a healthy, chemical-free intertidal environment with natural rock surfaces will allow native algae to grow, which in turn provides food for the limpets.

They are specialized grazers that eat 'biofilm'—a mixture of microscopic algae, diatoms, and very young seaweed plants that grow on the surface of rocks.

They are very common in any suburban area that borders a rocky Pacific coastline. You can often find them on jetty rocks, seawalls, and natural rocky beaches near coastal neighborhoods.

The Plate Limpet (Lottia scutum) is generally flatter and smoother than the Shield Limpet (Lottia pelta). The best way to distinguish them is by looking at the inside of an empty shell: the Plate Limpet has a distinct dark, owl-shaped brown stain in the center, whereas the Shield Limpet has a more varied internal pattern.

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