Humilaria kennerlyi (Reeve, 1863)

Common name(s): Corrugated clam, Ribbed clam, Kennerly's venus
Synonyms:Marcia kennerleyi, Humilaria kennerleyi Humilaia kennerlyi
Phylum Mollusca
Class Bivalvia
Subclass Heterodonta
Order Veneroida
Humilaria kennerlyi from soft bottom at 120 m depth of Yellow Island, San Juan Channel, WA.  Length about 6 cm.
(Photo by: Dave Cowles, July 2007)
Description:As with all members of Family Venereidae,  this species has a true hinge plate with 3 teeth on each valve (photos) but no chondrophore.  It has a continuous pallial line and a pallial sinus (photo).  The two adductor muscles and their scars are of similar size.  The hinge ligament is mostly external (photo).  This species has no radial ribs, its height is not more than 3/4 the length, and the angle at the umbones is more than 110 degrees.  The umbones are between the center and the anterior end.  The concentric ridges on the outside of the shell are sharply raised and often angle like saw teeth back toward the umbo (photo).  The periostracum is brownish and flaky.  She shell is white inside and chalky white outside (though it may be stained black if in anoxic sediments), and can close tightly at the posterior end. Length up to 10 cm.

How to Distinguish from Similar Species:Saxidomus gigantea gapes at the posterior end and its concentric ridges do not bend toward the umbones, plus it can grow to much larger than 10 cm. Protothaca staminea has radial ribs and has small serrations on the ventral margins of the valves. Venerupis philippinarum also has radial ribs, the interior of its valves is yellowish, it often has a purple stain inside, and it tends to be longer in relation to its height.

Geographical Range:  Prince William Sound, AK to Santa Rosa Island, CA

Depth Range:  Intertidal to 45 m

Habitat:  Sand and gravel

Biology/Natural History:  This species is common but not abundant.  Predators include Cancer magister and the seastars Orthasterias koehleri and Pisaster brevispinus.  Seastars often attack this clam, which lives fairly shallowly in the sediment.  The clam closes so tenaciously that the shell ridges may chip before the clam will open.  Apparently this may sometimes deter predation by the seastars.

The concentric lines on this shell form a heart-like shape (lunule) in the region just anterior to the umbones if one looks at the shell from the anterior end.


 
 
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References:

Dichotomous Keys:
  Kozloff 1987, 1996
 

General References:
  Harbo, 1997
  Morris, 1966
  Morris et al., 1980
  O'Clair and O'Clair, 1998
  Rice, 1973
  White, 1976

Scientific Articles:

Web sites:

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


Hinge ligament
The hinge ligament is mainly external, as is common in Family Veneridae
 


Inside right valve

The pallial line has a well-developed pallial sinus (the notch on the left), which the long siphons are retracted into.  This is a view of the right valve.
The two adductor muscle scars are near the anterior and posterior ends and are of similar size.
 


Left hinge
(anterior = left)
Right hinge
(anterior = left)
Humilaria kennerlyi has three teeth on both the left and the right hinge, as is characteristic of family Veneridae.  Unlike some other members of the family, the posteriormost tooth on the right valve is not bifid.


With strong ridges
This individual, found subtidally near Rosario summer 2011, has stronger ridges.  Note that it has been drilled by a mollusk.  Photo by Dave Cowles, Aug 2011



Authors and Editors of Page:
Dave Cowles (2007):  Created original page
CSS coding for page developed by Jonathan Cowles (2007)