Pyura haustor differs in having siphonal
spines (Sanamyan and Sanamyan 2006).
He mentioned as main shell differences in Bulliinae the lack of a recurved siphonal
channel with a carina on the dorsal side of the fasciole, and the reduced ornamentation.
Nucella trancosana is a low-spired thick-shelled species with strong apertural teeth that extend into the aperture as ribs, a short siphonal
canal, and numerous spiral cords (up to 24) on the body whorl.
APLEN Aperture length, the length from the suture of the aperture to the tip of the siphonal
Sipho thick basally narrower distally; siphonal
capsule very weakly hook shaped with opposite arm distinctly large broader cylindrical while adjacent arm very small narrow; median lobe narrow apically slightly longer than parameres; trabes apically bifurcated.
Description: Shell fusiform with truncated base; b/l 0.35-0.38, a/l 0.38-0.41; whorls strongly convex with narrow angular shoulder, and undulant, fairly deep suture, base of last whorl without a waist-like constriction; rostrum narrow, without a fasciole; aperture narrowly elliptical; siphonal
canal strongly contracted but slightly expanded terminally, end truncate, oblique in dorsal view, not notched.
bugensis in the anatomy of the siphonal
region, but it remains to be seen if this character state endures future scrutiny, especially among populations occurring within the native range of Dreissena spp.
Not included in this length-frequency analysis were 7.8% of OC, 9.0% of ES, and 6.3% of VB whelk landed on-board with broken siphonal
canals, which were largely the result of culling practices on board commercial vessels (personal experience) and result in inaccurate length measurements.
deltoidea individuals used in the trials ranged in size from 19.1 mm siphonal
length (SL; the distance from the apex to the tip of the siphonal
canal) to 44.8 mm SL (mean [+ or -] 1 SE = 33.0 [+ or -]1.1 mm SL).
length of all conchs was measured and used to evaluate the size distribution in each zone.
The shell lengths were taken from the apex to the distal end of the siphonal
The elongated and tubular shape of the shell, with siphonal
and pedal gapes, facilitates penetration into the substrate, whereas ejection of water through the pedal gape liquefies the surrounding substrate (Stanley 1975, Checa & Cadee 1997).