Rock entodesma, northwest ugly clam, wrinkled rock clam • Entodesma navicula
Left: rock entodesma siphons visible between anemone columns. Photo by Rosie Child. Right: one shell valve from a rock entodesma. Note the flattened and somewhat deformed shape, and the golden brown periostracum. Photo by Kelly Fretwell.
Identification
This clam has blue-tinged siphons tipped with orange; often only the siphons will be visible protruding from a rock crevice while the shell remains unseen. The flattened shell valves often appear deformed and are covered in a golden brown to greenish periostracum. The shell can get up to 10 cm long and gapes at the posterior end (click here for information on shell orientation).
Habitat & Range
The rock endostema is found in holes and crevices in rocks. It often developes within these enclosed areas and so its growth conforms to the shape of the space available. It is also found attached to giant barnacles and kelp holdfasts. It inhabits the low intertidal and subtidal to a depth of 20 m. Its range extends from northern Alaska to northern Mexico.
Similar Species
If only the siphons are visible, with the rest of the shell wedged between rocks, the pair of siphons may be mistaken for a tunicate.
iNaturalist
https://www.inaturalist.org/taxa/339164-Entodesma-navicula
This clam has blue-tinged siphons tipped with orange; often only the siphons will be visible protruding from a rock crevice while the shell remains unseen. The flattened shell valves often appear deformed and are covered in a golden brown to greenish periostracum. The shell can get up to 10 cm long and gapes at the posterior end (click here for information on shell orientation).
Habitat & Range
The rock endostema is found in holes and crevices in rocks. It often developes within these enclosed areas and so its growth conforms to the shape of the space available. It is also found attached to giant barnacles and kelp holdfasts. It inhabits the low intertidal and subtidal to a depth of 20 m. Its range extends from northern Alaska to northern Mexico.
Similar Species
If only the siphons are visible, with the rest of the shell wedged between rocks, the pair of siphons may be mistaken for a tunicate.
iNaturalist
https://www.inaturalist.org/taxa/339164-Entodesma-navicula
References
Adams, M.J. Entodesma navicula (Northwest ugly clam). Beach Watchers. Washington State University. Accessed 18/12/2014.
Lamb, A., and Hanby, B. (2005). Marine Life of the Pacific Northwest [electronic version]. Madeira Park, BC: Harbour Publishing.
Cowles, D. (2005). Entodesma navicula A. Adams and Reeve, 1850. Invertebrates of the Salish Sea. Rosario Beach Marine Laboratory. Accessed 18/12/2014.
Authors and editors of page
Kelly Fretwell and Brian Starzomski (2014).
Adams, M.J. Entodesma navicula (Northwest ugly clam). Beach Watchers. Washington State University. Accessed 18/12/2014.
Lamb, A., and Hanby, B. (2005). Marine Life of the Pacific Northwest [electronic version]. Madeira Park, BC: Harbour Publishing.
Cowles, D. (2005). Entodesma navicula A. Adams and Reeve, 1850. Invertebrates of the Salish Sea. Rosario Beach Marine Laboratory. Accessed 18/12/2014.
Authors and editors of page
Kelly Fretwell and Brian Starzomski (2014).