Tectura persona (Rathke, 1833)

Common name(s): Mask Limpet, Masked limpet, Speckled limpet, Large variegated limpet, Inflated limpet
Synonyms:  Notoacmea persona, Acmaea persona
Phylum Mollusca
 Class Gastropoda
  Subclass Prosobranchia
   Order Patellogastropoda
    Suborder Nacellina
     Family Lottiidae
Tectura persona crawling along a rock in the upper midlittoral at night on Sares Head
(Photo by: Dave Cowles, Sept 2005)
Description:  This limpet has the apex at the highest point of the shell and about 1/3 of the way back from the anterior margin.  The apex is usually slightly inclined forward.  The height of the shell is over 1/3 the width.  The posterior and lateral slopes of the shell are convex, giving the shell an inflated profile.  The inside of the shell is white with a large, dark apical blotch (photo) and a dark line or dark spots around the margin.  The outline of the shell is oval, and the length is usually 1.3 times the width or more.  There are no prominent ribs, though small, low ones may be present.  The coloring is usually speckled and banded brown, greenish brown, or olive-green with tan or white speckles.  Large, with length up to 5 cm, but usually about 3 cm.

How to Distinguish from Similar Species:  This is the only large, inflated limpet found in the upper midlittoral zone.  Tectura scutum looks very similar but it is much flatter, with a height not more than 1/3 the width.

Geographical Range:  Aleutian Islands to Isla Socorro, Mexico; less common south of Monterey Bay, CA

Depth Range:  Upper midlittoral

Habitat:  Underside of rocks and ledges during the day, more wide-ranging at night

Biology/Natural History:  This large, common intertidal species is negatively phototactic, so they are usually in crevices  or on the underside of boulders during the day.  It is commonly found on the roofs of sea caves.  They come out to feed at night.  It is one of the largest limpets that can be found in the intertidal here in the Pacific Northwest (though it does not get as large as the owl limpet, Lottia gigantea, which is found further south).  The white spots on the shell are translucent, and may be used to help the animal avoid bright light.  The gut of this species often has a large parasitic protozoan, Eupoterian pernix.  This species can be found in brackish water.  Predators include black oystercatchers, which capture many of them in the Rosario area, and crows, which may explain why they usually retreat to high up on vertical surfaces or under overhangs, in shaded places during the day.  They are most common in the upper midlittoral so seastars and oyster drill snails are less likely to be a problem for them.  They do not show an escape response to sea stars, as do some lower-living limpets such as the keyhole limpet Diodora aspera.  In California, spawning is in March and April.

The "persona" in the name refers to the dark stain on the interior of the apex, which sometimes looks like a mask or a person's face.


 
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References:

Dichotomous Keys:
  Flora and Fairbanks, 1966 (as Acmaea persona)
  Kozloff 1987, 1996
  Smith and Carlton, 1975 (as Notoacmea persona)

General References:
  Brusca and Brusca, 1978 (as Notoacmea persona)
  Carefoot, 1977 (As Notoacmea persona)
  Harbo, 1997
  Harbo, 1999
  Johnson and Snook, 1955 (as Acmaea persona)
  Kozloff, 1993
  McConnaughey and McConnaughey, 1985 (as Notoacmea persona)
  Morris, 1966 (as Acmaea persona)
  Niesen, 1997
  O'Clair and O'Clair, 1998
  Ricketts et al., 1985 (as Notoacmea persona)
  Sept, 1999

Scientific Articles:
Bullock, T.H., 1953.  Predator recognition and escape responses of some intertidal gastropods in the presence of starfish.  Behavior 5: 130-140
 

Web sites:
 


General Notes and Observations:  Locations, abundances, unusual behaviors:

A student study at Rosario by Pick and Reiswig (2007) found that the black oystercatchers Haematopus bachmani nesting on Northwest Island are being selective in the limpets they capture.  Although Lottia digitalis was the most common limpet found in intertidal transects on Northwest Island and were the species found at the highest tide levels so they should have been more available than any other species, they were not the most abundant in shell middens found near the oystercatcher nesting and feeding site.  The oystercatchers selected Lottia digitalis less often than expected, and those they did select were near the maximum size range found in the intertidal.  The oystercatchers seemed to prefer other, larger limpet species such as Tectura persona, Tectura scutum, and Lottia pelta, all of which were found by chi-squared analysis to be in significantly higher numbers in the midden than expected from the intertidal abundance.  Whether this selection by the oystercatchers is due to a specific selection of species or simply a selection of the largest individuals present in the intertidal is not known.
 


In this view one can see the apex which inclines forward; the inflated nature of the posterior slope of the shell, and the fact that this limpet is much taller than is Tectura scutum.
Night photo by Dave Cowles, Sept 2005.


This individual was at Swirl Rocks.  Total length about 3-4 cm.  Photo by Dave Cowles, July 2007



The degree of development of the apical blotch and the dark marginal line can vary considerably, as seen in this assemblage of Tectura persona shells collected near a black oystercatcher nesting and feeding area.
Photo by Dave Cowles, July 2007


Authors and Editors of Page:
Dave Cowles (2005):  Created original page