Cancellate Hairysnail

How to Distinguish from Similar Species: Several other Trichotropis species have an aperture at least half the height of the shell. May look like a small Oregon triton Fusitriton oregonensis, but the aperture is more circular in Trichotropis.

Areas of strong currents and little mud. Often under subtidal rocks, among tunicates and tubeworms. May climb up the tubes of large tubeworms.

Depth Range: Extreme low intertidal to 200 m. Mostly subtidal

Members of Family Trichotropidae have a coiled, raised spire, much of the periostracum is in the form of hairs or bristles, and have no siphonal notch or canal. Trichotropis cancellata has 6-7 whorls, an aperture less than half the height of the shell, and a diameter about 2/3 the shell height. The shell has both small longitudinal and 4-5 pronounced spiral ridges. The periostracum is light brown. Length to about 4.2 cm.

Biology/Natural History: This species is a filter feeder. It traps microscopic particles in mucus, which it then swallows. Since its food comes from suspended particles it has no need to move around much. It mounts a stone or other object out of the mud and remains there for a long time. Deep-water individuals frequently have the tiny white parasitic snail Odostomia columbiana next to the aperture. Odostomia uses its eversible proboscis to suck body juices from Trichotropis. Trichotropis also often has ascidians, hydroids, diatoms, sponges, barnacles, or other sessile animals growing on it. This species is a protandric hermaphrodite. For its first year it is a male, then becomes female but retains the penis. Females lay disk-shaped egg capsules at night, then die. Cancellate means checkered. The spiral and longitudinal ridges form a checkered pattern on the shell, but the pattern is often hard to see because of the thick hairy periostracum.

Geographical Range: Bering Sea to Oregon