Acanthochitona zelandica

Acanthochitona zelandica
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Polyplacophora
Order:	Chitonida
Family:	Acanthochitonidae
Genus:	Acanthochitona
Species:	A. zelandica
Binomial name
Acanthochitona zelandica (Quoy & Gaimard, 1835)
Synonyms
Chiton zelandicus Quoy & Gaimard, 1835 Acanthochoetes hookeri Gray, 1843 Acanthochiton zealandicus doubtessensis Ashby, 1926 Acanthochiton brookesi Ashby, 1926 Acanthochiton zelandicus amplificatus Iredale & Hull, 1930

Acanthochitona zelandica is a species of chiton in the family Acanthochitonidae, also sometimes known as the hairy, or "tufted", chiton.^[1] It probably developed during the mid to late Pleistocene, and is endemic to New Zealand.^[2]

Description

Acanthochitona zelandica has an oval shaped body, growing up to 30.1 mm in length and 20 mm in width.^[3] The individual median valves of the shell, excluding the head and tail, are small, usually no more than 5 mm wide and 4 mm long.^[4] The shell and girdle are generally light brown, with darker brown spots across the shell. The girdle is adorned with small bunches of spines for protection, leading to the pseudonyms "hairy" or "tufted" chiton.

Distribution

Acanthochitona zelandica is found off the coast of New Zealand around the North, South, Stewart, and Auckland Islands, including the Otago Peninsula and the great Bay of Islands.^[5] It is less common off the more exposed, west coast beaches.^[6] It occupies the intertidal and shallow sub-tidal areas, in depths of up to 10 meters.^[7] A. zelandica lives primarily on, underneath, and in the crevices of coastal rocks.^[5] It has been observed living in clumps of the Pacific oyster Magallana gigas, most likely to avoid being smothered by increasing mud levels.^[8]

Anatomy

As

The Acanthochitona zelandica mouth is similar to that of other mollusks. It is associated with two salivary glands and uses a thin strap with rows of teeth, known as the radula, to graze and bottom-feed.^[12] As the organism wears through the front rows of the teeth, they are discarded or swallowed, then replaced by new rows that move forward.^[12] Unique to chitons, one pair of cusps in each row is coated with magnetite, reinforcing the teeth to be stronger than stainless steel.^[12] They are the only mollusks that have magnetite-coated teeth, and the only organisms known to produce such large amounts of magnetite.^[12]

Diet

While larger chitons have been known to eat large algal blades, encrusting colonial animals, or even engage in predatory behavior to trap and consume mobile animals, Acanthochitona zelandica is a grazer and uses the radula to scrape algal films and built-up diatom layers off of tidal rocks.

References