Tresus nuttallii

FMIB_34793_Shell_of_Schizothaerus_nuttalli,_the_'Great_Blue_Clam'

Tresus nuttallii, commonly known as the Pacific gaper clam or horse clam, is a species of saltwater clam in the family Mactridae. This species is native to the Pacific Ocean and is found along the western coast of North America, from Alaska to Baja California.

Description

The shell of Tresus nuttallii is large and heavy, typically reaching lengths of up to 20 cm (8 inches). The exterior of the shell is white to light brown, often covered with a thin, dark periostracum. The interior of the shell is smooth and white. The clam has a long siphon, which it uses to filter feed and respire while buried in the substrate.

Habitat

Tresus nuttallii inhabits sandy and muddy substrates in the intertidal and subtidal zones, often at depths of up to 30 meters. It is commonly found in estuaries, bays, and sheltered coastal areas where it can burrow deeply into the sediment.

Life Cycle and Reproduction

The Pacific gaper clam is a broadcast spawner, releasing eggs and sperm into the water column where fertilization occurs. The larvae are planktonic and undergo several developmental stages before settling to the bottom and metamorphosing into juvenile clams. Tresus nuttallii can live for over 20 years, with some individuals reaching ages of up to 30 years.

Ecological Role

As a filter feeder, Tresus nuttallii plays a significant role in the ecosystem by filtering plankton and organic particles from the water, thus contributing to water clarity and quality. It is also an important prey species for various predators, including sea otters, crabs, and seabirds.

Human Use

Tresus nuttallii is harvested both commercially and recreationally for its edible meat. It is considered a delicacy in many coastal communities and is often used in clam chowder and other seafood dishes. Harvesting is typically done by hand digging or using specialized clam guns.

Conservation Status

Currently, Tresus nuttallii is not listed as an endangered or threatened species. However, its populations can be affected by overharvesting, habitat degradation, and pollution. Sustainable harvesting practices and habitat protection are essential for maintaining healthy populations of this species.

See Also

• Mactridae
• Clam
• Filter feeder
• Intertidal zone
• Estuary