Calyptraea fastigiata Gould, 1846

Common name(s): Cup-and-saucer snail, Pacific chinese hat snail

Phylum Mollusca
 Class Gastropoda
  Subclass Prosobranchia
   Order Mesogastropoda
    Suborder Taenioglossa
     Family Calyptraeidae
Calyptraea fastigiata shell (dead) collected subtidally near Northwest Island
(Photo by: Dave Cowles, July 2005)
Description:  This limpetlike gastropod has a conical shell that is almost circular in outline.  Inside it has a spiral septum (shelf) with a twisted free edge that spirals about half a turn (photo).  Exterior of live individuals is white, interior pearly.  Diameter to 2.5 cm

How to Distinguish from Similar Species:  Slipper shells such as Crepidula adunca have a septum inside but the shells are more flattened, and the septum also is mostly flat rather than spiral.  The shells of chinese cap limpet Acmaea mitra has a similar shell shape but no septum inside and usually has steeper sides and a higher apex..

Geographical Range:  Alaska to California

Depth Range:  Occasionally intertidal, mostly subtidal at 18 to 137 m

Habitat:  Attached to rocks, dead shells, or sometimes to crabs

Biology/Natural History:  As with other slipper shells, this species is a filter feeder with special gills.

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Dichotomous Keys:
  Kozloff 1987, 1996

General References:

  Harbo, 1997
  Morris, 1966

Scientific Articles:

Web sites:

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

Inside the shell there is a spiral septum, or shelf, which twists about 1/2 revolution
This 1.8 cm-diameter individual was collected and photographed by Dave Cowles, July 2020
Outside view
Inside view

In the small, live individual below (1 cm diameter) a light yellow periostracum can be seen clinging to the shell plus the tip (apex) or protoconch of the shell, which is the remains of the shell the animal first formed after the larva settled, shows a clear spiral, demonstrating the species' affinity to other snails even though the external parts of its shell are not coiled as an adult. The protoconch typically wears off by the time the shell reaches full size so the spiral is generally not as evident. Photo by Dave Cowles, August 2021
Coiled shell apex

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