Acanthochitona fascicularis is a common chiton

Chiton

Chitons are small to large, primitive marine molluscs in the class Polyplacophora.There are 900 to 1,000 extant species of chitons in the class, which was formerly known as Amphineura....

 in the family Acanthochitonidae

Acanthochitonidae

Acanthochitonidae is a family of chitons.-Description:These small to large chitons are characterised by a broad girdle with erect tufts of up to ten large bristles. The coarsely granular valves of the shell are partially overlapped by the girdle. This girdle is all covered by coarse spines. The...

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Distribution and habitat

This chiton has been recorded in European waters, the Mediterranean Sea

Mediterranean Sea

The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...

, the Red Sea

Red Sea

The Red Sea is a seawater inlet of the Indian Ocean, lying between Africa and Asia. The connection to the ocean is in the south through the Bab el Mandeb strait and the Gulf of Aden. In the north, there is the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez...

 and the Pacific Ocean

Pacific Ocean

The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

. It is usually found on the lower shore and the sublittoral zone  to a depth of 50 m on hard surfaces, such as on or under rocks, boulders or in rock crevices

Description

The shell of Acanthochitona fascicularis has an elongate, flat oval shape and is about twice as long as broad. It has a length of up to 60 mm. The color may be variable; being marbled with off-white, gray, yellowish or brown. The eight transverse valves of the shell are strongly arched with a rounded keel and prominent beaks. The keel shows longitudinal ridges and appears coarsely granular due to densely packed, oval or rounded and evenly arranged dorsal papillae. The girdle contains 18 tufts of bristles (maximum length : 1.5 mm), one on each side at the back of the plates. Four of these bristles are arranged around the cephalic plate. The sculpture of the valves consists of a cover with densely packed, backward-pointing spines that are regularly distributed and give a velvety feel when touched. The girdle is fringed with a dense series of longer spines (up to 1 mm).

This species can be confounded with Acanthochitona crinita, but this last one is smaller (about 30 mm) and the granules on the dorsal plates are large, flat topped and pyriform and unevenly spaced.

Feeding habits

This chiton is a grazer that feeds on encrusting or filamentous algae and possibly bryozoans.