California lampshell

Laqueus californianus

ORDER

Terebratulida

FAMILY

Laqueidae

TAXONOMY

Laqueus californianus Koch, 1848.

OTHER COMMON NAMES

English: Smooth lampshell.

PHYSICAL CHARACTERISTICS

The shell of California lampshells is medium to moderately large in size, with an adult dimension of 0.79–1.97 in (20–50 mm). The tan-colored shell is biconvex and may be smooth or ribbed. The pedicle is short to moderately long. The loop that supports the lophophore passes through one or more bilacunar phases. The lophophore is plectolophous, which means that it has longer lateral lobes and a coiled median lobe. Spicules occasionally occur scattered over the mantle canals. Dental plates are present. The ventral median septum (partition) is weak. Hinge plates are variably developed.

DISTRIBUTION

California lampshells are found near the break between the continental shelf and slope along the western coast of the United States.

HABITAT

California lampshells live in the continental shelf zone at depths of 325–650 ft (100–200 m). They are also found in tropical to cold surface waters and in deeper waters.

FEEDING ECOLOGY AND DIET

California lampshells are believed to eat dissolved silt as well as organic matter, diatoms, dinoflagellates, and phytoplankton, but may not be limited to these items.

BEHAVIOR

California lampshells are generally sedentary or sessile in their lifestyle, attaching themselves to substrates by their pedicles. They are usually found with the ventral shell uppermost and the valves slightly apart.

REPRODUCTIVE BIOLOGY

The eggs of California lampshells are 0.00512–0.00551 in (130–140 μm) in diameter, and the sperm are unmodified. At 50°F (10°C) an embryo develops within 72 hours, and gastrulation occurs within 24–38 hours. A three-lobed larva with an attachment disk develops in about seven days. The larvae, however, die within one day at 77°F (25°C). At 68°F (20°C), development is normal but may result in abnormal settlement of larvae. At 59°F (15°C), 50°F (10°C), and 41°F (5°C), most larvae achieve competence in five, seven, and nine days, respectively. Settlement and metamorphosis can occur within one day after the larvae make contact with the substrate.

CONSERVATION STATUS

Not listed by IUCN.

SIGNIFICANCE TO HUMANS

None known.