The Exotics Guide

Mya arenaria Image 4-five left valves

Left valves of Mya arenaria shells collected from San Francisco Bay shores. The head ends of the shells are to the left. The largest is about 10 cm long.

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Mya arenaria Image 3-stained shell

Mya arenaria from San Francisco Bay, with its shell stained rusty from the mud. The head end is to the left, and the siphons protrude slightly at the right.

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Mya arenaria Image 2-dark shell

Mya arenaria from San Francisco Bay, with its shell stained dark from the anoxic mud it was living in. The head end is to the right.

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Mya arenaria Image 1 & Key

Mya arenaria from San Francisco Bay. The head end is to the right, with the dark siphons protruding slightly from the hind end of the shell at the left.

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Mya arenaria Linnaeus, 1758

SOFT-SHELL CLAM, EASTERN SOFT-SHELL CLAM, LONG-NECKED CLAM, STEAMER CLAM, SAND GAPER

  • Kingdom: Animalia
  • Phylum: Mollusca
  • Class: Bivalvia
  • Subclass: Heterodonta
  • Order: Myoida
  • Superfamily: Myoidea
  • Family: Myidae

Mya arenaria has a chalky white, oval shell which is rounded at the head end and slightly pointed at the hind end. It can reach up to 15 cm in length. Young clams have a thin gray, yellow or brown tissue covering the shell, which is worn away in older clams except around the shell margins. In some areas the shells are reported to be blue-white or brownish-white rather than chalky white, and the mud the clam lives in can stain the shell rusty or black.

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Musculista senhousia Image 5

Closeup of the Musculista senhousia mat. A few anemones (Diadumene lineata) attached to the mussels are visible at the left and lower right.

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Musculista senhousia Image 4

A mat of Musculista senhousia, within a bed of the larger bay mussel (Mytilus trossulus-galloprovincialis complex) on the east shore of San Francisco Bay.

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Musculista senhousia Image 3

Musculista senhousia from San Francisco Bay, with its siphons extended upward from the hind end of shell, and its long foot extended to the lower left corner of the image.

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Musculista senhousia Key Image

Another specimen from San Francisco Bay. This one lacks the dark, wavy, concentric lines, and the radiating lines are pale purple against a greenish-yellow and brown background. Note the very slightly concave lower edge of the shell, at left.

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Musculista senhousia Image 1

Musculista senhousia from San Francisco Bay. Note the shell’s green tint, faint purple radiating lines, and dark purple-brown, wavy, concentric lines.

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