Cockles are broad, high
shells with radial
ribs, 2 adductor
muscle scars of nearly equal size, cardinal
Clinocardium nuttallii has a thick
shell, is just as high or slightly higher (dorsal
distance) than long (anterior
end), has more than 30 (often around 35) distinct radial
ribs covering the entire valve.
The ridges become undulations on the ventral
margins of the valves, which interlock with one another (photo).
Height up to 14 cm, but usually less than 5 cm. Shell is usually light
tan, mottled with various bands or blotches of brown (photo),
especially in younger individuals. Its siphons
are short (photo).
When buried in the sand,
appear white with white hairs radiating from their tips, and with small
white globules inside the rim of the incurrent
siphon. The cockle's profile from the side is
Common name(s): Heart cockle,
Nuttall's cockle, basket cockle
|Clinocardium nuttallii, 4 cm
long and 4.2 cm high.
|(Photo by: Dave
Cowles, July 2005)
How to Distinguish
from Similar Species: Other
cockles in the area have an area in the posterior
quarter that has prominent concentric ridges as well as radial
ribs, or are wider than high; and do not get larger than
about 4 cm.
The littleneck clam Protothaca staminea has much
and the ventral
margin does not undulate.
Range: Bering Sea to San Diego,
CA; Japan; very common in Rosario area.
Depth Range: Low
intertidal to 200 m; mostly
intertidal and shallow subtidal
sediment, especially muddy
fine sand (not plain mud). Lies barely buried in the
Often in eelgrass beds.
Growth rings may
be prominent, especially in the northern parts of its range, as this
nearly ceases feeding in winter. Yearly growth lines are much
prominent farther south, but tidal cycle growth lines can often be
with tiny eyes. Pumps 2.51 liters of water per hour per gram
weight. Predators include Pycnopodia
magister, and gulls. The cockle has a
strong escape response
extending its foot and jumping away (movie).
May be a source of paralytic shellfish poisoning (PSP) for
A simultaneous hermaphrodite
(has both functional male and female gonads at the same
In Puget Sound they mature in their second year and spawn in July and
Live 15-19 years in Alaska. May contain small pea crabs such
faba inside the mantle cavity.
and Fairbanks, 1966 (as Cardium corbis)
and Carlton, 1975
and Brusca, 1978
and Snook (1955) (as Cardium corbis)
and McConnaughey, 1985
et al., 1980
and O'Clair, 1998
et al., 1985
General Notes and
Observations: Locations, abundances,
We find this species to be the most commonly found
bivalve in western
Padilla Bay, along the east side of March Point.
Clinocardium nuttallii shells have various
brown bands and blotches
on the valves.
Cockles have two adductor
muscle scars of nearly equal size, and cardinal
teeth. Photo of Clinocardium nuttallii
shell by Dave Cowles,
The same photo as above, with many of the features
ribs interlock as undulations along the ventral
margin, which likely strengthens the shell by making the two valves
to twist apart. I am holding the two valves
slightly apart here to clearly show the gap--in full closure they
tightly. Photo by Dave Cowles, July 2005
A side view shows why this cockle is called the heart cockle.
Photo by Dave Cowles, July 2005
view shows the umbones
and external hinge.
Photo by Dave Cowles, June 2020
Clinocardium nuttallii has short
siphons, mainly white.
Note that the incurrent
siphon is larger than the excurrent
siphon, as is common in many bivalves.
Photo by Dave Cowles, July 2007
This species jumps rapidly by extending its foot when it
seastars such as Pycnopodia
helianthoides or Pisaster
ochraceus. Click here for
a movie of the jump near Pycnopodia.
Authors and Editors of Page:
Dave Cowles (2005): Created original page