Overview

Comprehensive Description

Biology/Natural History: This common clam lies on its left side instead of vertically, at a depth of 10-20 cm. It rocks back and forth while digging. The siphons extend out the right side and up to the surface, which are well accomodated by the twist to the right of the shell. The siphons are used to suck debris from the surface of the sediment like a vacuum cleaner. The clams digest mainly diatoms and some flagellates from the sediments. They ingest large quantities of sediment but reject 97% of it, producing copious pseudofeces (photo). Hinton says the clam moves to another location when the sediment in an area has been thoroughly picked over. Predators include the moon snail Polinices lewisii. The clam was an important food of the coastal Indian tribes and to Chinese immigrants in San Francisco but is little used commercially today because of the debris that is usually in the gut. This species is very hardy and can be found in areas that have very poor circulation, and can live in very soft, silty mud. The pea crab Pinnixa littoralis or P. faba may live in the mantle cavity, as may the Nemertean worm Malacobdella grossa. The species spawns in early summer in Oregon.

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Source: Invertebrates of the Salish Sea

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Like all members of family Tellinidae, this clam has a rounded shell with neither valve very flat nor very inflated, and the anterior and posterior ends are shaped differently. There are two adductor muscle scars of similar size on each valve. The umbones are near the middle of the dorsal side. It has no radial ribs. The hinge has a true hinge plate with two cardinal teeth on both valves. The hinge ligament is mostly external. The valves have a pallial sinus and a continuous pallial line. The valves gape only slightly, if at all, at the posterior end. The siphons are long and separate (photo). Macoma nasuta has a long hinge ligament, no lateral teeth on its hinge plate, is less than twice as long as high, and the posterior end of both valves is bent to the right (photo). The pallial sinuses are large, extend to beneath the anterior adductor muscle scars, and are very close to the pallial line ventral to them. Length to 11 cm but usually not more than 6 cm. Shells are chalky white and usually unstained, with some grayish-brown periostracum.
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Source: Invertebrates of the Salish Sea

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Distribution

Geographical Range: Kodiak Island, Alaska to Cabo San Lucas, Baja California, Mexico

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Physical Description

Look Alikes

How to Distinguish from Similar Species: This is the only clam in this area that has the posterior ends of the valves bent to the right.
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Source: Invertebrates of the Salish Sea

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Ecology

Habitat

Depth range based on 75 specimens in 1 taxon.
Water temperature and chemistry ranges based on 9 samples.

Environmental ranges
  Depth range (m): 0 - 108
  Temperature range (°C): 8.197 - 12.466
  Nitrate (umol/L): 3.089 - 23.180
  Salinity (PPS): 31.538 - 33.458
  Oxygen (ml/l): 3.695 - 6.561
  Phosphate (umol/l): 0.565 - 1.851
  Silicate (umol/l): 8.443 - 31.328

Graphical representation

Depth range (m): 0 - 108

Temperature range (°C): 8.197 - 12.466

Nitrate (umol/L): 3.089 - 23.180

Salinity (PPS): 31.538 - 33.458

Oxygen (ml/l): 3.695 - 6.561

Phosphate (umol/l): 0.565 - 1.851

Silicate (umol/l): 8.443 - 31.328
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.
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Depth range based on 75 specimens in 1 taxon.
Water temperature and chemistry ranges based on 9 samples.

Environmental ranges
  Depth range (m): 0 - 108
  Temperature range (°C): 8.197 - 12.466
  Nitrate (umol/L): 3.089 - 23.180
  Salinity (PPS): 31.538 - 33.458
  Oxygen (ml/l): 3.695 - 6.561
  Phosphate (umol/l): 0.565 - 1.851
  Silicate (umol/l): 8.443 - 31.328

Graphical representation

Depth range (m): 0 - 108

Temperature range (°C): 8.197 - 12.466

Nitrate (umol/L): 3.089 - 23.180

Salinity (PPS): 31.538 - 33.458

Oxygen (ml/l): 3.695 - 6.561

Phosphate (umol/l): 0.565 - 1.851

Silicate (umol/l): 8.443 - 31.328
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

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Depth Range: Low intertidal to 50 m

Habitat: Buried in mud flats; also found in gravel, sand, or muddy clay

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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage: Macoma nasuta

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Specimens with Barcodes: 4
Species With Barcodes: 1
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Source: Barcode of Life Data Systems (BOLD)

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Wikipedia

Macoma nasuta

Macoma nasuta is a species of bivalve found along the Pacific Ocean coast of North America. It is often found buried in sands of 10 to 20 centimeters in depth.[1] This rounded clam has no radial ribs and is commonly called the bent-nosed clam.[2] There is archaeological data to support the use of this species by Native Americans such as the Chumash peoples of central California.[3]

Names[edit]

Macoma nasuta is commonly known as the Bent-nosed clam or Bent-nose Macoma.[4] It is commonly misidentified as either Macoma tersa or Macoma kelseyi[4]

Description[edit]

The hinge plate is without lateral teeth and the length of shell much less than twice the height. Posterior portions of both valves distinctly bent to the right with the siphons distinctly separated (as they are in all Macoma) and have a distinct orange pigmentation. The periostracum is usually very prominent and the shell has a dirty brown wrinkled look to it, especially near the margin.[5]

Distinguishing characteristics[edit]

Valves bent rather sharply to the right at the posterior end, orange coloration of its siphons and periostracum is usually very prominent.[4]

Size[edit]

About 5 cm at widest point from the anterior end to the posterior end.[6]

Habitat[edit]

Common in intertidal and subtidal (50 m) zones; Prefers mud to muddy sand substrates situated in quiet waters and can burrow up to 40 cm beneath the surface sediment. M. nasuta and M. secta are geographically sympatric species and both are the characteristic species of Macoma on the west coast of North America.[7]

Range[edit]

Found in the neritic provinces of the eastern Pacific Ocean from Kodiak Island, Alaska, to Cabo San Lucas, Baja California.[8]

Feeding and digestion[edit]

Found to feed off the top millimeter of sediment by using a boring motion with the tip of its siphon into the sediment or by using a rotating motion similar to Scrobicularia plana.[9] New sediment is found by moving the siphon into virgin sediment but the clams have also been ob served to consume their pseudofeces and feces. It is assumed that the siphon tip is unselective in the particles it intakes.[10]

Non-specific nematodes have been found in the stomach in all stages of digestion from live to empty cuticles. The small (about 500 μm) Bivalve Transenella tantilla has also been found living in the stomach. The relationship with both nematodes and T. tantilla is uncertain.[10]

The exhalant siphon is kept below the sediment surface (about 1 cm). The gut clearance time for inert particles of M. nasuta ranges from 1 to 9 hours with smaller particles and diatoms believed to remain longer than other particles ingested due to their disproportionably high presence in the stomach during dissections.[10]

Bioaccumulation of toxins[edit]

Due to their feeding behavior of deposit feeding M. nasuta have been found to have a high level(s) of DDT and PCB’s.[11]

Reproduction[edit]

M. nasuta is a dioecious (probably gonochoristic) species that spawns in early summer.[8][12]

Natural history[edit]

There is archaeological data to support the use of this species by Native Americans such as the Chumash peoples of central California.[3]

Predators[edit]

Shore birds, Lewis' Moon Snail: Polinices lewisii, Starfish: Pisaster spp., Crabs: Cancer productus, Metacarcinus gracilis, Metacarcinus magister.[6]

Known parasites[edit]

Graffilla Pugetensi[13] is a known parasite of the pericardial cavity and Telolecithus pugetensi[14] is known to use M.nasuta as a second intermediate host in T.pugetensi’s life cycle.

References[edit]

  1. ^ Macoma nasuta profile
  2. ^ Bent-nosed clam
  3. ^ a b C. Michael Hogan, Los Osos Back Bay, The Megalithic Portal, ed. Andy Burnham (January, 2008)
  4. ^ a b c Dave Cowles (2005). "Macoma (Heteromacoma) nasuta (Conrad, 1837)". Walla Walla University. 
  5. ^ KOZLOFF, E. 1996. Marine invertebrates of the Pacific Northwest, Univ. Wash. Press ISBN 0-295-97562-8
  6. ^ a b KOZLOFF, E. 2001. Seashore life of the northern Pacific coast, Univ. of Wash. Press ISBN 0-295-96084-1
  7. ^ SEPT, J. DUANE 1999. The beachcombers guide to seashore life in the Pacific Northwest, Harbor Publishing ISBN 1-55017-204-2
  8. ^ a b [RAE III, J.G. 1978. Reproduction in two sympatric species of Macoma (Bivalvia). Biol. Bull. 155: 207-219.]
  9. ^ HUGHES, R.H 1969. A study of feeding in Scrobicularia plana. Journal of Marine Biology Assn. U.K. 49: 805-823.
  10. ^ a b c HYLLEBERG, J. AND V.F. GALLUCCI 1975. Selectivity in feeding by the deposit-feeding Bivalve Macoma nasuta. Journal of Marine Biology, 32: 167-178.
  11. ^ BOESE, B.L., LEE II, H. AND S. ECHOLS 1997. Evaluation of a first-order model for the prediction of the bioaccumulation of PCB’s and DDT from sediment into the marine deposit-feeding clam Macoma nasuta. Setac Journal of Environmental Toxicology and Chemistry. 16:1545-1553.
  12. ^ Bivalves of The Evergreen State College Campus
  13. ^ SCHELL, S.C. 1986. Graffilla pugetensis n. sp. (order Neorhabdocoela: Graffillidae), A parasite in the pericardial cavity of the bent-nose clam, Macoma nasuta (Conrad, 1837). Journal of Parasitology, 72: 748-754.
  14. ^ DEMARTINI, J.D AND PRATT, I. 1964. The life cycle of Telolecithus pugetensis Lloyd and Guberlet, 1932 (Trematoda: Monorchidae). Journal of Parasitology, 50: 101-105.
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