Blue Green Chiton

Chiton glaucus

Description 11

Common, oval chiton, about 37mm long (some sources say up to 55mm), 22mm (up to 35mm) wide. Strongly arched, the plates tend to be clean smooth and shiny.

Overall the plates and girdle are usually the same colour. The colour of the plates usually dark yellowish-green but may be anything in a range from yellowish-brown with green marks, or clear yellow with green or brown rays (occasionally uniformly reddish-brown).

The girdle is narrow and composed of small smooth scales all of a similar size. Their overall colour is the same hue as the plates, but individual scales may be of different shades, reflecting the colours found on the body plates.

The plates seem smooth but the front plate is covered in numerous faint fine radial lines. These radial lines are also present on the other plates from the back of the crest to the outer edge, and the rest of the plate surface has fainter parallel lines running from front to back. The second plate is longer than those that follow, and each is slightly beaked at the peak. The front and rear plates are about the same size.

The inside of the plates is light blue, front plate has 9, occasionally 10, slits. The rear plate has 13 or 14 slits, and the rest have one slit on either outer edge.

Distribution 11

Abundant in intertidal zone, usually found hiding on the undersides of stones when the tide is out.
North Island, South Island and Stewart Island.

Synonyms 11

Amaurochiton glaucus (Gray, 1828)
Chiton aquatilis (Reeve, 1847)
Chiton quoyi (Deshayes, 1836)
Chiton quoyi limosus (Suter, 1905)
Chiton tenuistriatus (G. B. Sowerby II, 1840)
Chiton viridis (Quoy and Gaimard, 1835)

References 11

New Zealand Mollusca, Marine Land and Freshwater Shells, A W B Powell, 1979
The New Zealand Sea Shore, John Morton and Michael Miller, 1968.
A photographic guide to Seashells of New Zealand, Margaret S. Morley, 2004.
Manual of the New Zealand Mollusca. Henry Suter, 1913

Sources and Credits

  1. (c) tangatawhenua, some rights reserved (CC BY-NC),
  2. (c) Natalie Tapson, some rights reserved (CC BY-NC-SA),
  3. (c) Ken-ichi Ueda, some rights reserved (CC BY),
  4. (c) anmar2015, some rights reserved (CC BY-NC), uploaded by anmar2015,
  5. (c) Tony Wills, some rights reserved (CC BY-SA),
  6. (c) tangatawhenua, some rights reserved (CC BY-NC),
  7. anonymous, no known copyright restrictions (public domain),
  8. (c) Lisa Bennett, some rights reserved (CC BY),
  9. (c) Lisa Bennett, some rights reserved (CC BY),
  10. Dumont d'Urville, Jules-Sébastien-César, no known copyright restrictions (public domain), uploaded by Tony Wills,
  11. (c) Tony Wills, some rights reserved (CC BY-SA)

More Info

iNaturalist NZ Map

Depth intertidal
Places North Island, South Island, Stewart Island