Haustrum haustorium, (common name: the brown or dark rock shell) is a large species of predatory sea snail, a marine gastropod mollusc in the family Muricidae, the murex snails or rock snails.
Haustrum haustorium used to be the only species in the genus Haustrum. However, Beu (2004) reclassified a number of New Zealand's whelks, considering the genera Lepsiella (species: Lepsiella scobina) and Lepsithais (species: Lepsithais lacunosa) to be synonyms.
This species is endemic
to New Zealand
This rock snail is typically found in the mid and lower eulittoral
zone of New Zealand's semi-exposed rocky intertidal
shores. It is less common on algal-dominated sheltered shores.
The shell is rather large and solid with a low conical spire
, and a rapidly expanding body whorl
that tapers gradually to the anterior end. The aperture
is large, and the outer lip is thin and crenulated. The inner lip has a broad smooth excavated callus
is coarse uneven spiral ridges, separated by linear grooves. The operculum
The coloration of the exterior of the shell is dull purplish-brown, with the aperture and parietal callus
white except for a splash of reddish-brown within, and a border of purplish-brown streaks inside the outer lip.
A reliable characteristic for distinguishing Haustum haustorium
from its congeners
is the angle by which the aperture
lip inserts on the shell: In Haustrum haustorium
the angle is near-perpendicular
, whereas in other species the angle is more acute (~45 degrees). Tan (2003) provides the most recent review.
The food of this species varies regionally, but generally consists of other gastropods (including other whelks such as the oyster borer
). Juveniles often feed on barnacles
. Access is gained by the rock snail drilling through the prey's shell with its radula
. Large specimens of Haustrum haustorium
can also dislodge the operculum of their prey directly by smothering prey and enveloping it with their mantle
Historic specimens attain a shell height up to 65 mm, and a width of up to 45 mm. Today, however, it is difficult to find individuals larger than 55 mm.
- Powell A W B, New Zealand Mollusca, William Collins Publishers Ltd, Auckland, New Zealand 1979 ISBN 0-00-216906-1
- Glen Pownall, New Zealand Shells and Shellfish, Seven Seas Publishing Pty Ltd, Wellington, New Zealand 1979 ISBN 85467 054 8
- Miller M & Batt G, Reef and Beach Life of New Zealand, William Collins (New Zealand) Ltd, Auckland, New Zealand 1973
- Beu, A. G. 1990. Molluscan generic diversity of New Zealand Neogene stages: extinction and biostratigraphic events. - Palaeogeography, Palaeoclimatology, Palaeoecology 77: 279-288.
- Tan, K. S. 2003. Phylogenetic analysis and taxonomy of some southern Australian and New Zealand Muricidae (Mollusca: Neogastropoda). - Journal of Natural History 37: 911–1028.