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Fissurellidea bimaculata

(Two-Spot Keyhole Limpet)

Overview

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Interesting Facts

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Common Names

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Common Names in English:

Two-Spot Keyhole Limpet

Description

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Family Fissurellidae

Shell with a dorsal opening at or near the apex, or with a slight indentation at the anterior margin (such an indentation is present only in the rare and subtidal Arginula bella; it marks the place where a groove on the interior of the shell, beginning at the apex, reaches the margin )

Physical Description

Species Fissurellidea bimaculata

This keyhole limpet has a large brown, red, orange, or yellow mantle which covers so much of the shell that the animal looks very much like a nudibranch at first. The body is much larger than the shell, which only covers the area around the dorsal opening (aperture ) and may be mostly covered by mantle. The opening in the small shell is about 1/3 the shell length. Shell length to 2 cm (usually 1.6 cm or less), and has gray or brownish radiating ridges dorsally , smooth white ventrally. Animal length to at least 3 cm. When free from the animal the shell has a shallow groove around the margin and the ends may turn up slightly (see photo). I do not know why it is called the two-spot keyhole limpet.[1]

Habitat

On compound tunicates or sponges under rocks, or on kelp holdfasts . Depth Range : Intertidal to shallow subtidal .[1]

Typically found in water with a depth of 0 to -47 meters (0 to -154 feet).[2]

Biome: Marine .

Biology

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Diet

Seems to feed on sponges and compound tunicates , and may also feed on phytoplankton (their stomach contains a crystalline style, which is characteristic of plankton feeders such as bivalves ).[1]

Behavior

Predators:

Predators include harlequin ducks.[1]

Taxonomy

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Synonyms

Megatebennus bimaculatus

Notes

Name Status: Accepted Name .

Last scrutiny: 30-Dec-2004

Similar Species

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Other keyhole limpets here do not have a shell which is so small in comparison to the body, nor is the aperture equal to about a third of the shell length. Be careful not to mistake it as a dorid nudibranch (the apex looks much like the anus and gills of a dorid but is surrounded by a small, mostly hidden shell and is just behind the head instead of on the posterior end of the body as seen in dorids). (Ref. 109953)

Members of the genus Fissurellidea

ZipcodeZoo has pages for 1 species and subspecies in this genus:

F. bimaculata (Two-Spot Keyhole Limpet)

More Info

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Further Reading

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Notes

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Contributors

Data Sources

Accessed through GBIF Data Portal January 30, 2008:

Identifiers

Footnotes

  1. Cowles, Dave. Key to Invertebrates Found At or Near The Rosario Beach Marine Laboratory (a campus of Walla Walla University) Fidalgo Island, Anacortes, WA May 2009. [back]
  2. Mean = 45.470 meters (149.180 feet), Standard Deviation = 117.550 based on 15 observations. Ocean depth information for each observation from British Oceanographic Data Centre. [back]
Last Revised: 7/20/2012