Wednesday 31 August 2016

9 — Cuvier's siphon whelk, Penion cuvierianus

The same shell as above (~150mm).
Cuvier's siphon whelk, Penion cuvierianus (Powell, 1927) is a large gastropod whelk (up to 235mm) endemic to northeastern New Zealand. They are found from just offshore to the edge of the continental shelf (>180m). The shallow water forms can look very similar to another, more common species: Penion sulcatus (Lamarck, 1816), and can be difficult to distinguish from it. Of the species in this genus, Penion sulcatus is the species that people find washed up on beaches, as it has a distribution from the intertidal down to about 100m. The genus Penion is quite old and dates back in the fossil record almost to the Cretaceous period (Beu & Maxwell, 1990).

Penion cuvierianus, trawled, Bay of Plenty ~1960s.
These whelks are vulnerable to the bottom trawling activities of commercial fishing. Very little is known regarding their distribution, numbers, or how long they take to grow to maturity. It's important to know these basic biological data, as they are quite large shells and could be depleted before they are reproductively mature. Not that much is known about their ecology either, and for the most part this has been extrapolated from closely related shallow water species; it is assumed that they are predators/scavengers.



More info:

http://www.mollusca.co.nz/speciesdetail.php?speciesid=1121&species=Penion%20cuvierianus

Some 3d scans http://www.nzfauna.ac.nz/penionc

This fossil guide is available free online:

Beu AG, Maxwell PA 1990. Cenozoic Mollusca of New Zealand. New Zealand Geological Survey Paleontological Bulletin 58, 1990 ISSN 0114-2283

Tuesday 30 August 2016

8 — Fan shell, Talochlamys gemmulata

Talochlamys gemmulata, Castlecliff Beach,
Wanganui, 11/89.
Talochlamys gemmulata (Reeve, 1853) is a small fan shell (up to ~50mm) endemic to New Zealand . They are closely related to scallops (Family: Pectinidae) and are found on the continental shelf, down to ~300m depth. They can also live in relatively shallow water and so they do wash up occasionally on beaches. What’s interesting about these particular shells is that they are fossils and were collected (by me) from Castlecliff Beach, Wanganui in November 1989.

There are banks of fossiliferous sediment just up past the dunes at Castlecliff and shells (and other marine fossils) continuously fall out if them. These fossil deposits are thought to date back to at least the Pleistocene, which means that these two shells could be upwards of a million years old. These fossils are morphometrically identical to living populations, so I think it’s interesting to see how little this species has changed.



More info:

http://www.gns.cri.nz/static/Mollusca/taxa/BM488.html

http://www.mollusca.co.nz/speciesdetail.php?speciesid=2280&species=Talochlamys%20gemmulata

Monday 29 August 2016

7 — Deep-sea top shell, Maurea (Alertalex) alertae

Maurea (A.) alertae from
Challenger Plateau, TAN0707.
Maurea (A.) alertae from
Challenger Plateau, TAN0707.
Maurea (Alertalex) alertae is a deep-sea snail (gastropod) endemic to New Zealand. It is found in waters ~200–700m deep. They are an attractive, nacreous, shiny little shell, and grow to about 25mm.

While not much is known regarding the ecology of this particular species, it is thought that closely related species feed on hydroids and/or sponges.



















More info: 

http://www.mapress.com/mr/content/v31/2011f/n2p135.htm

https://www.niwa.co.nz/news/critter-of-the-week-a-beautiful-group-of-marine-snails-the-calliostomatidae 

More pictures: http://www.mollusca.co.nz/speciesdetail.php?speciesid=194&species=Calliostoma%20%28Otukaia%29%20alertae

5 — Neoguraleus amoenus

Neoguraleus amoenus
 * is a small snail (gastropod), about 12mm in size, which is endemic to northern New Zealand. Like most of the small New Zealand marine snails, not much is known about its distribution, or its ecology. They are related to cone shells, but belong in the family Mageliidae. This species is found offshore on the continental shelf, so they don’t tend to wash up very often.
*(E.A. Smith, 1884)

More info:

More pictures: http://www.mollusca.co.nz/speciesdetail.php?speciesid=1359&species=Neoguraleus%20amoenus