Semicassis royana

Semicassis royana is a species of very large predatory sea snail, a marine gastropod mollusc. This species is in the subfamily Cassinae, the helmet shells and bonnet shells, which feed on sea urchins.

Distribution

This species is found along the east coast of Northland in the North Island of New Zealand, and in New Zealand's Kermadec Islands.

Habitat

This sea snail lives at depths of between 35 and 45 m.

Shell description

The shell is very large and solid, with a tall spire, angled at the shoulder, and with two rows of blunt tubercles, the upper row the stronger. The outer lip has a heavy rounded smooth varix. The inner lip callus shield is smooth and adpressed, bridging a very small umbilical cavity.

Life habits

At the Poor Knights Islands it is known to eat the giant heart urchin Brissus gigas.

Shell description

The shell coloration is light pinkish-brown, with four or five spiral bands, irregularly maculated, and crossed by meandering axial streaks of reddish-brown. The labial varix and end of the siphonal canal is dark purplish-brown, and the callus shield is cream to orange-brown at its outer edge.

The maximum shell height is 151 mm, and width 83 mm.

References

• Powell A. W. B., William Collins Publishers Ltd, Auckland 1979 ISBN 0-00-216906-1