Geoduck

== Description ==
The Pacific geoduck (“gooey-duck”; ; Panopea generosa ) is a species of very large saltwater clam in the family Hiatellidae. The common name is derived from the Lushootseed (Nisqually) word gʷídəq.
== Appearance ==
Pacific geoduck clams are one of the largest known clams in the world, with an average shell length of 135 to 140 mm, but individuals are reported to reach shell lengths of over 200 mm. Their shells are generally quadrate (square-shaped) and have a thin, light brown outer layer, called the periostracum. In addition to their large shells, Pacific geoduck clams have a siphon that may extend over 1 m to reach out of substrate to the surface of the seabed. Pacific geoduck clams are reported to reach masses of over 3 kg in total. Juveniles have a large foot relative to their body size, which they use to dig into substrate on the seafloor. As Pacific geoduck clams mature, their foot gradually becomes proportionally smaller as they grow to adult size and lose the ability to dig. There are no significant differences in size between male and female Pacific geoduck clams, and sex can only be determined by microscopy of the gonads. Males usually achieve sexual maturity at a younger age and a smaller size. Environmental conditions, such as chemical concentrations, substrate composition, and water temperature, can affect the size, color, and shape of Pacific geoduck clam shells.
== Distribution ==
Pacific geoduck clams (Panopea generosa) are native to temperate waters of the Pacific Ocean and subtropical areas of the Mexican Pacific. Populations of Pacific geoduck clams are concentrated off the west coast of North America, especially in Puget Sound. However, the geographic distribution of Pacific geoduck clams extends north to Alaska and south to Punta Canoas, on the peninsula of Baja California. As commercial fisheries attempt to expand geoduck aquaculture, individuals have recently been reported as far south as Guerrero Negro in Baja California Sur.
== Lifestyle ==
Pacific geoduck clams are burrowing clams and individuals have been found buried up to 3 feet deep in the substrate of intertidal and subtidal zones along the northwestern coast of the United States. Due to their sedentary lifestyles as adults, individuals spend the majority of their development moving to and burrowing in an appropriate place in mud or sand. Pacific geoduck clams larvae are motile and can move relatively easily throughout the water column. However, the post-larval dissoconch Pacific geoduck clams develop a ciliated foot that allows them to crawl along the seafloor and begin burrowing into substrate. Post-larval dissoconch Pacific geoduck clams also release byssal threads from their foot, which allow them to anchor themselves to substrate. Juveniles begin burrowing into substrate using their foot until only their siphon is left exposed above the surface. As they develop and their siphon grows longer, individuals burrow deeper into the sand, up to a depth of 3 feet. As they develop into adults, their bodies grow and their foot becomes proportionally small, thus limiting the ability of adults to dig deeper into substrate. Adults are sedentary and move rarely, if at all.
== Diet ==
Pacific geoduck clams are filter feeders, consuming microbes and other particles that they sift from the water column. They have ciliated ctenidia, or gills, that transport food particles to their labial palps, after which food passes through their digestive system.
== Reproduction ==
Pacific geoduck clams are dioecious and reproduce sexually. Reproduction occurs via broadcast spawning, wherein both sexes release their gametes into the water column and fertilization occurs externally. Pacific geoduck clam adults are sedentary and are incapable of digging with their foot. Therefore, once buried in substrate, they remain there throughout their life. Adults reproduce sexually by spawning in a simple annual reproductive cycle. Males and females produce their gametes in September and spawning occurs from March to July. Spawning is usually triggered by increasing water temperature, though other cues, such as changes in water chemistry, can also affect the timing of spawning. Male Pacific geoduck clams typically begin the spawning process by releasing sperm, which in turn prompts females and other males to release their gametes. Females may produce up to one billion eggs, but only release a few million during each spawning event.
== Gallery ==
File:Geoduck4.jpeg
File:Geoduck5.jpeg
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File:Geoduck.webp
File:Geoduck1.webp
== Main References ==
https://animalia.bio/geoduck
https://animaldiversity.org/accounts/Panopea_generosa/
Category:Animalia
Category:Animals
Category:Mollusca
Category:Molluscs
Category:Bivalvia
Category:Adapedonta
Category:Hiatellidae
Category:Panopea