The shape and the idea: 94 — Siphon whelk, Penion sulcatus

Saturday 26 November 2016

94 — Siphon whelk, Penion sulcatus

Penion sulcatus, Enclosure Bay,
Waiheke Island, in ~1m, Feb 2015.

The siphon whelk, Penion sulcatus (Lamarck, 1816) is a moderately large whelk (~170mm), endemic to New Zealand and found from low-tide down to depths of ~100m. They like areas of medium wave exposure where there is a mixture of sand and rock. However, they can also be found in muddy inshore habitats and also off exposed sandy beaches, so they seem indifferent to the sediment type. They are not what you would call common, but you will occasionally see them washed up after a storm with ostrich foot shells (Struthiolariidae).

Siphon whelks are very easily confused with P. cuvierianus, which is a deeper-living species (although the deep end of P. sulcatus' distribution overlaps the shallow end of the distribution for P. cuverianus). Their shell morphology overlaps as well, but generally speaking, P. sulcatus has coarser sculpture and the shell is of a heavier build than P. cuvierianus.

Penion sulcatus are thought to feed on bivalves (particularly Dosina spp. and Condylocardia crassicosta Bernard, 1897—but probably others, depending on habitat). This is another species I've seen live amongst the low-tidal rocks along Tamaki Drive in central Auckland.