Family  Hipponicidae & Calyptraeidae


Home > Northwest Shells & Marine Life > PNW Shells & Marine Life Photos > Gastropods >  Gastropods - Hipponicidae
                                                                                                                                                                        & Calyptraeidae

Click on photo to enlarge.  Scale line in photo equals 1cm unless otherwise specified.
* Species which are commonly encountered on the beach.

Calyptraea fastigiata Calyptraea fastigiata
                                  Whiskey Creek Beach, WA                                                            Anacortes, WA, intertidal
Calyptraea fastigiata Gould, 1846
Cup-and-Saucer Snail
intertidal to 137m          southern California to central Alaska          size to 25mm
This is occasionally found intertidally.  It can easily be confused with the Whitecap Limpet until it is overturned.  This shell has a partial shelf on the underside.  It is also a thinner shell than the limpet.  

Hipponix panamensis
Makah Bay, WA
Hipponix panamensis
 C.B. Adams, 1852

Flat Hoofsnail
intertidal to subtidal          northern Mexico to BC          size to 25mm
This is infrequently found on the open coasts.  It is more common in California.
The shell shape and growth are irregular and often encrusted.  It clings to rocks.
(synonyms - Antisabia panamensis, Antisabia cranioides, Hipponix cranioidesHipponix serratus, Hipponix antiquatus - an Atlantic species)

Crepidula convexa Say, 1822
Atlantic Convex Slipper-shell
intertidal          size to 25mm
southern California to southern BC; Caribbean to Massachusetts
This is infrequently found.  It was introduced to the west coast from the Atlantic.  It looks similar to our native C. adunca except that the  the apex is folded far forward.  In the northwest it is only found in isolated populations.  It is usually attached to dead shells in our area.
(synonym - Crepidula glauca)

Crepidula nummaria 
Waddah Island, WA

Crepidula nummaria Gould, 1846
Northern White Slipper-shell
intertidal to subtidal          size to 46mm
northern California to northern Alaska
This species is found on the outer coast attached to rocks or dead shells. It typically has a shaggy brown periostracum.  There is a notch on the left edge of the interior shelf.   The interior is glossy white.   

Crepidula fornicata Crepidula fornicata
                                                 Penrose Point, WA                                                                           Big Fishtrap Cove, WA, intertidal
Crepidula fornicata (Linnaeus, 1758)
Eastern Slipper-shell
intertidal          Texas to Canada; introduced to Washington and BC, Japan and Europe          size to 50mm
This is usually common to find where it has established a population within the Salish Sea.  The shell usually has brown spots or blotches.  It has a thin brown periostracum which is often worn away.
The interior has a bright white shelf. Then shell is generally inflated.  On the east coast it is often found in stacks of several shells on top of each other.  In our area we rarely observe more than one male on top of a female shell.  

Crepidula convexa Crepidula convexa
                            Boundary Bay, BC                                                                     Willapa Bay, WA

Crepidula convexa
Willapa Bay, WA, intertidal

Crepidula fimbriata
Johnstone Strait, BC

Crepidula fimbriata Reeve, 1859
Frilled Slipper-shell

intertidal to subtidal          size to about 23mm
Salish Sea, at least Johnstone Strait BC to Strait of Juan de Fuca BC and WA
This species prefers protected  and transitional waters rather than the outer coast.  It is found on rocks and dead shells.  It often has frilled margins and a dark brown interior stain but these features may also be absent.  It has no periostracum.

Crepidula williamsi
Yakan Point, Haida Gwaii, BC
Crepidula williamsi Coe, 1947
Hermit Crab Slipper-snail
intertidal to subtidal          size to 15mm
California to Alaska
This species is commonly found inside the aperture of dead snail shells which are also occupied by hermit crabs.  It may also be found on other dead shells.  The shell is mainly white with a dark stain or radiating lines on the tip of the apex.  It is also elongated in shape.

Species in the Calyptraeidae family are sequential hermaphrodites, meaning they change sex at some point during their life.  In the case of the Slipper shells, one often sees a large female shell with one or more smaller males attached to the back of its shell.  As the female ages and dies, the males grow and  morph into females, with new young males attaching to their shells.

Crepidula perforans
Ucluelet, BC, intertidal
Crepidula perforans (Valenciennes, 1846)
Western White Slipper-shell
intertidal to subtidal          size to 38mm
northern Mexico to Kodiak, AK
  This species is found on the outer coast where it resides under rocks.  It can sometimes be found in the holes of boring clams.  The shell is smooth and white with a glossy interior.  It tends to have an elongated shape and a thin, light-colored periostracum.

Crepipatella lingulata Crepipatella lingulata
                                  Bremerton, WA                                              Big Fishtrap Cove, WA, intertidal
Crepipatella lingulata (Gould, 1846)
Wrinkled Slipper-shell *
intertidal to 100m          California to northern Alaska          size to 25mm
This is commonly found intertidally.  The shell is mostly circular but irregular based on the surface where it is living.  The exterior is somewhat wrinkled with a thin periostracum.  Tan to mauve blotches may also be evident.  The apex is near the margin.  On the interior the small shelf sits under the apex.  This has frequently been called C. dorsata, but that is considered a tropical species.
(synonyms - Crepidula lingulata, Crepidula fissurata)

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This page last revised: 5-25-2019
Crepidula adunca Crepidula adunca Crepidula adunca
                        Whiskey Creek Beach, WA                                              Neah Bay, WA, intertidal                  Whiskey Creek Beach, WA, intertidal
Crepidula adunca G.B. Sowerby I, 1825
Hooked Slipper-shell
intertidal to 19m          northern Mexico to northern BC          size to 25mm
This species is found on the outer coast and in transitional waters. It is frequently attached to other shells such as Calliostoma, Tegula, Nucella and Lirabuccinum.  It may also be found on rocks.  The shell is brown with a brown periostracum.  The interior is chocolate brown with a white shelf. The apex is usually high and hooks forward. The hooked apex creates a pit within the shelf in the interior.  
(synonym - Garnotia adunca)

Crepidula onyx Crepidula onyx
                    Bremerton, WA                                                            Bremerton, intertidal
Crepidula onyx (Sowerby, 1824)
Onyx Slipper-shell
intertidal to 90m          Chile to southern California; Washington          size to 70mm
This was introduced to Puget Sound.  It is occasional found where it has established populations.  This shell has a yellowish-brown periostracum and occasional brown markings.  The interior is chocolate brown with a bright white shelf.   

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