Clinocardium nuttallii

recent & fossil

Biology/Natural History: Growth rings may be prominent, especially in the northern parts of its range, as this species nearly ceases feeding in winter. Yearly growth lines are much less prominent farther south, but tidal cycle growth lines can often be seen. Mantle margin has tiny tentacles with tiny eyes. Pumps 2.51 liters 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 humans. A simultaneous hermaphrodite. In Puget Sound they mature in their second year and spawn in July and August. Live 15-19 years in Alaska. May contain small pea crabs such as Pinnixa faba inside the mantle cavity.

Cockles are broad, high shells with radial ribs, 2 adductor muscle scars of nearly equal size, cardinal and lateral hinge teeth (picture). Clinocardium nuttallii has a thick shell, is just as high or slightly higher (dorsal to ventral distance) than long (anterior to posterior end), has more than 30 (often around 35) distinct radial ribs covering the entire valve. The ridges becomes undulations on the ventral margins of the valves, which interlock with one another (picture). Height up to 14 cm, but usually less than 5 cm. Shell is usually light tan, mottled 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 is heart-shaped (picture).

Geographical Range: Bering Sea to San Diego, CA; Japan; very common in Rosario area.

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 less prominent radial ribs and the ventral margin does not undulate.

Depth range based on 118 specimens in 1 taxon.
Water temperature and chemistry ranges based on 42 samples.

Environmental ranges
  Depth range (m): -2 - 152
  Temperature range (°C): 6.640 - 12.466
  Nitrate (umol/L): 3.089 - 22.690
  Salinity (PPS): 31.235 - 33.114
  Oxygen (ml/l): 3.837 - 6.794
  Phosphate (umol/l): 0.565 - 2.182
  Silicate (umol/l): 8.443 - 47.770

Graphical representation

Depth range (m): -2 - 152

Temperature range (°C): 6.640 - 12.466

Nitrate (umol/L): 3.089 - 22.690

Salinity (PPS): 31.235 - 33.114

Oxygen (ml/l): 3.837 - 6.794

Phosphate (umol/l): 0.565 - 2.182

Silicate (umol/l): 8.443 - 47.770
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

Depth Range: Low intertidal to 200 m; mostly intertidal and shallow subtidal

Habitat: Fine sediment, especially muddy fine sand (not plain mud). Lies barely buried in the sediment. Often in eelgrass beds.