75 — Turret shell, Maoricolpus roseus

Maoricolpus roseus, under Ngapipi Bridge,
Tamaki Drive, 2016.

The turret shell, Maoricolpus roseus (Quoy & Gaimard, 1834) is a medium-sized shell (~80mm) found throughout New Zealand from just below low tide down to at least 130m. Somehow, (possibly through ballast water exchange) they have become established as an invasive species in parts of southern Australia, especially Tasmania, where it was first seen in the 1920's.

Maoricolpus roseus, under Ngapipi Bridge,
Tamaki Drive, on a day with low
visibility in 2015.

They are suspension feeders (capturing food floating passed using a mucous net) and often live in tidal channels where there is considerable water flow. They are dominant members of these communities and can be found in great numbers.

Three Maoricolpus roseus with a colony of thecate
hydroids, under Ngapipi Bridge,
Tamaki Drive, 2015.

More info:

Hayward BW, Stephenson AB, Morley M, Riley JL, & Grenfell HR 1997. Faunal changes in Waitemata Harbour sediments, 1930s–1990s. Journal of the Royal Society of New Zealand. 27:1, 1–20, DOI: 10.1080/03014223.1997.9517525