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| Pacific Blue
Mussel |
(Mytilus
trossulus) |
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Description:
Found in dense colonies. Blue to black to brown. Interior pearly.
Soft body protected by two hinged calcified shells (valves).
Siphons draw in water that is filtered for food and oxygen.
Attach to rocks and pilings by strong "byssal threads."
Grows to 2.5 inches locally. This species of mussel can live
to 1 - 2 years. |
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| Food:
Water drawn into the siphons is filtered for plankton and detritus. |
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Reproduction:
Large numbers of eggs produced by female. |
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| Fun
Facts: This species can pump up to 3 quarts of water
an hour through its gills in order to filter out plankton! |
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| California
Mussel |
(Mytilus
californianus) |
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Description:
Found in dense colonies. Prefers very strong wave/tidal action.
Shell blue to black to brown. Interior grayish blue. Soft body
protected by two hinged calcified shells (valves). Siphons draw
in water that is filtered for food and oxygen. Attached to rocks
and pilings by strong "byssal threads." Shells thicker
and rougher that Blue Mussels. Grows to 8 inches locally, growing
3 inches a year. |
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| Food:
Water drawn into the siphons is filtered for plankton and detritus. |
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| Reproduction:
Up to 100,000 eggs produced annually by female. |
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| Fun
Facts: Often host to immature Pea Crabs. This Mussel
can contain tiny pearls of varying shapes. |
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| Rock
Oyster |
(Pododesmus
cepio) |
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Description:
Also known as a "Jingle Shell." Nearly round when
viewed from above, this oyster has a thin lower shell that conforms
to the shape of the rock to which it is anchored. The upper
shell is curved and thicker. Anchored through hole in lower
shell. To 5 inches or more. |
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| Food:
Filter feeder. When shells open and actively pumping water to
filter for plankton the bright reddish-orange flesh of the animal
is visible. |
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| Reproduction:
Bivalves are typically gonochoristic (having separate male and
female individuals), fertilization is external, and the developing
larva (veliger) settles to the bottom after a time in the plankton.
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|
| Fun
Facts: The name "Jingle Shell" comes from
the sound a handful of these shells make in the pocket of a
beachcomber. |
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| Olympia
Oyster |
(Ostrea
lurida) |
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Description:
Also known as the "Native Pacific Oyster." Found in
sheltered Puget Sound bays. Attaches to rocks. Gray to white
gnarled shells. Pollution, over harvesting and slow maturation
have resulted in sharply reduced numbers of this species. Grows
up to 3.5 inches. |
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| Food:
Filter feeder. |
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| Reproduction:
Alternates between male and female each breeding season. Maturation
in 4 to 6 years. |
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| Fun
Facts: The female holds young inside her mantle
until their shells develop. |
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| Pacific
Oyster |
(Crassostrea
gigas) |
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Description:
Also known as the "Japanese Oyster." Introduced from
Japan in the early 1900's, this exotic species became naturalized
and is an important commercial crop. Thick, fluted white or
gray shells. Grows up to 12 inches. |
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| Food:
Filter feeder. |
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| Reproduction:
The natural reproduction of this species is poor in our area,
so commercial growers import tiny oysters each year. |
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| Fun
Facts: This oyster may live up to 20 years, and
sometimes contains irregular pearls! |
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| Heart
Cockle |
(Clinocardium
nuttallii) |
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Description:
Oval shells with heart-shaped cross section. Prominent ribs
radiating from the hinge. On older individuals the ribs can
be worn smooth. Color varies from tan to quite dark. Mottling
common. Found in tidal flats near surface. Paired siphons. Can
live up to 16 years and reach 5.5 inches in size. Ensure area
is safe from red tide before harvesting. |
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| Food:
Filter feeder. |
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| Reproduction:
Maturation
in 2 years. Bivalves
are typically gonochoristic (having separate male and female
individuals), fertilization is external, and the developing
larva (veliger) settles to the bottom after a time in the plankton.
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|
| Fun
Facts: Thick shell is brittle and cracks open easily
when dropped onto rocks by gulls. |
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Native
Littleneck |
(Protothaca
staminea) |
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Description:
Also known as the "Steamer Clam." Found just below
the surface of tidal flats. Fused siphons short. Similar in
shape to Heart Cockle, but shells thinner and more flattened.
Many fine ridges radiate out from the hinge. These ridges are
crossed by growth rings. White to tan; sometimes stained with
geometric patterns. Can live up to 14 years and grows to 4 inches.
Ensure area is safe from red tide before harvesting. |
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| Food:
Filter feeder. |
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| Reproduction:
Bivalves are typically gonochoristic (having separate male and
female individuals), fertilization is external, and the developing
larva (veliger) settles to the bottom after a time in the plankton.
This clam grows and repopulates slowly, taking 4 to 6 years
to reach commercial size. An over harvested bed may take 25
years to reestablish itself. |
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| Fun
Facts: These clams are often predated upon by Moon
Snails, which leave a characteristic hole drilled near the hinge
as evidence of their appetite. |
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| Manila
Clam |
(Tapes
philippinarum/japonica) |
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Description:
Also known as the "Japanese Littleneck." The shells
(valves) are more oblong than that of the Native Littleneck.
Abundant just below the surface in sheltered bays and tidal
flats. Varies from gray to brown, with streaking pattern radiating
from the hinge common. Can live up to 14 years, and grows up
to 3 inches. Ensure area is safe from red tide before harvesting. |
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| Food:
Filter feeder. |
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| Reproduction:
Bivalves are typically gonochoristic (having separate male and
female individuals), fertilization is external, and the developing
larva (veliger) settles to the bottom after a time in the plankton.
Grows to commercial size in just 2 years. |
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| Fun
Facts: This clam was accidentally introduced into
Puget Sound in the 1920's in shipments of Pacific Oyster seed
stock. Species has out competed Native Littleneck in many places. |
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| Butter
Clam |
(Saxidomus
giganteus) |
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Description:
A large thick shelled clam. Gray to white. Shells can be stained
dark by iron sulfate. Prominent growth rings. Valves close together
tightly (unlike the Horse Clam). Found in the low intertidal
zone 8 to 14 inches below the surface. Can live up to 20 years,
and reaches 6 inches in size. Ensure area is safe from red tide
before harvesting. |
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| Food:
Filter feeder. |
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| Reproduction:
Bivalves are typically gonochoristic (having separate male and
female individuals), fertilization is external, and the developing
larva (veliger) settles to the bottom after a time in the plankton.
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|
| Fun
Facts: Considered the best clam for chowders! |
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Sand
Clam |
(Macoma
secta) |
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Description:
A thin shelled white clam found buried 8 to 16 inches in the
sands of sheltered bays and tidal flats. Faint growth rings.
Twin long white siphons. Grows up to 4 inches in diameter. |
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| Food:
Filter feeder specializing in detritus. |
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| Reproduction:
Bivalves are typically gonochoristic (having separate male and
female individuals), fertilization is external, and the developing
larva (veliger) settles to the bottom after a time in the plankton.
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|
| Fun
Facts: Valves have a sharp bend line along one edge.
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Bent-Nosed
Clam |
(Macoma
nasuta) |
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Description:
A thin shelled white clam found buried 4 to 6 inches in the
mud of sheltered bays and tidal flats. Lies on its side. Faint
growth rings. Twin long orange siphons. Grows up to 2 inches
in diameter. |
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| Food:
Filter feeder specializing in detritus. |
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| Reproduction:
Bivalves are typically gonochoristic (having separate male and
female individuals), fertilization is external, and the developing
larva (veliger) settles to the bottom after a time in the plankton.
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|
| Fun
Facts: When viewed edge-on valves are bent at an
angle. |
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| Soft-Shell
Clam |
(Mya
arenaria) |
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Description:
Thin, very brittle, elongated shells which are white to gray
in color. Found buried 4 to 8 inched in mud and sand in sheltered
bays and tidal flats. Long siphon does not retract fully. Prefers
areas of low salinity such as the mouths of rivers. Grows up
to 4 inches. |
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| Food:
Filter feeder. |
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| Reproduction:
Bivalves are typically gonochoristic (having separate male and
female individuals), fertilization is external, and the developing
larva (veliger) settles to the bottom after a time in the plankton.
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|
| Fun
Facts: This species is believed to have been introduced
from the Atlantic Ocean sometime around the 1920's. |
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| Horse
Clam |
(Tresus
capax) |
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Description:
Also known as the "Fat Gaper." Shells chalky white
edged with dark flaky covering called periostracum. Shells sometimes
stained dark by iron sulfides in the mud. Valves gape apart
around siphon which cannot retract fully. Found up to 20 inches
below surface in intertidal zone. When exposed at low tide this
clam can be seen spitting jets of water into the air when disturbed.
Can grow up to 10 inches locally. Ensure area is safe from red
tide before harvesting. |
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| Food:
Filter feeder. |
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| Reproduction:
Bivalves are typically gonochoristic (having separate male and
female individuals), fertilization is external, and the developing
larva (veliger) settles to the bottom after a time in the plankton.
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|
| Fun
Facts: This clam is often home to two tiny Pea Crabs
which live inside its shell. |
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| Geoduck |
(Panope
abrupta) |
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Description:
Pronounced "Gooey-duck." Found mostly subtidally.
Valves gape at end like the Horse Clam, but their shape is more
rectangular, with prominent concentric growth rings. Neck and
siphon my be 3 feet long. The largest intertidal clam in the
world, shells may exceed 8 inches, and total weight can reach
20 pounds. Harvested only on the lowest tides of the year. Ensure
area is safe from red tide before harvesting. |
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| Food:
Filter feeder. |
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| Reproduction:
Bivalves are typically gonochoristic (having separate male and
female individuals), fertilization is external, and the developing
larva (veliger) settles to the bottom after a time in the plankton.
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|
| Fun
Facts: Among the oldest of animals in the world.
Can live as long as 146 years! |
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| Rough
Piddock |
(Zirfaea
pilsbryii ) |
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Description:
White shells with brown periostracum covering. Shells are roughly
oval with teeth development at anterior end. Siphon end of shell
gapes. The siphon can extend up to 12 inches. This clam can
live up to 8 years, and its shell grows up to 4 inches. |
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| Food:
Filter feeder. |
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| Reproduction:
Bivalves are typically gonochoristic (having separate male and
female individuals), fertilization is external, and the developing
larva (veliger) settles to the bottom after a time in the plankton.
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|
| Fun
Facts: This clam rasps away at clay, or soft rock,
digging a circular burrow in which it lives until it dies. |
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| Copyright
© 2008-2009 City of Edmonds, Washington - All Rights Reserved |
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