12 — Spiny murex, Poirieria zelandica

Spiny murex (Poirieria zelandica)
Trawled, Bay of Plenty.

Spiny murex (Poirieria zelandica)
Trawled, Bay of Plenty.

The spiny murex (Poirieria zelandica * is an iconic New Zealand seashell. It’s found throughout New Zealand, from shallow water down to at least 500m. I have a dwarf form, which was collected in 520 m on the Challenger Plateau in 2007. The deeper water examples can have quite long spines, longer than the width of the body whorl. It is thought that the length of the spines is related to either the depth or the sediment type: muddier sediments mean longer spines.

Ecologically, they are thought to be active predators and/or scavengers, and there are anecdotal reports of them being pulled up on hand lines, still attached to the bait. Like many muricid whelks (Family: Muricidae) they use a combination of their radula (a kind of rasp-like organ) and secreted acid to bore into the shells of their prey. They move around by lifting their shell, lurching forward, and then putting the shell back down.

This particular spiny murex was trawled somewhere in the Bay of Plenty during the 1980's. It's about 50 mm in size.

* Quoy & Gaimard, 1833



For more info: 

https://www.niwa.co.nz/blogs/critteroftheweek/139

http://www.gns.cri.nz/static/Mollusca/taxa/BM528.html

http://www.mollusca.co.nz/speciesdetail.php?speciesid=1006&species=Poirieria%20zelandica