Cockles are broad, high
shells with radial ribs, 2 adductor muscle scars of nearly equal size,
cardinal and lateral hinge teeth (picture).
nuttallii has a thick shell, is just as high or slightly
to ventral distance) than long (anterior to posterior end), has more
30 (often around 35) distinct radial ribs covering the entire
The ridges becomes undulations on the ventral margins of the valves,
interlock with one another (picture).
up to 14 cm, but usually less than 5 cm. Shell is usually light tan,
with various bands or blotches of brown (picture),
especially in younger individuals. Its siphons are short (picture).
When buried in the sand, the siphon edges 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
Clinocardium nuttallii (Conrad, 1837)
Common name(s): Heart cockle,
Nuttall's cockle, basket cockle
|Clinocardium nuttallii, 4 cm long
and 4.2 cm high.
|(Photo by: Dave Cowles,
How to Distinguish from
Similar Species: Other
cockles in the area have an area in the posterior quarter that has
concentric ridges as well as radial ribs, or are wider than high; and
not get larger than about 4 cm. The littleneck clam Protothaca
staminea has much less prominent radial ribs and the ventral
does not undulate.
Geographical 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
Mantle margin has tiny tentacles with tiny eyes. Pumps 2.51
of water per hour per gram body weight. Predators include Pycnopodia
helianthoides, Pisaster brevispinus, and Cancer
magister, and gulls. The cockle has a
strong escape response
to Pycnopodia--rapidly extending its foot and
jumping away (movie).
May be a source of paralytic shellfish poisoning (PSP) for
A simultaneous hermaphrodite. In Puget Sound they mature in
second year and spawn in July and August. Live 15-19 years in
May contain small pea crabs such as Pinnixa
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
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
and lateral teeth. Photo of Clinocardium nuttallii
Dave Cowles, July 2005
The same photo as above, with many of the features labeled.
The radial ribs interlock along the ventral margin, which likely
the shell by making the two valves difficult to twist apart.
holding the two valves slightly apart
here to clearly show the gap--in full closure they interlock
Photo by Dave Cowles, July 2005
A side view shows why this cockle is called the heart cockle.
Photo by Dave Cowles, July 2005
Clinocardium nuttallii has short siphons,
Note that the incurrent siphon is larger than the excurrent siphon.
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