Local distribution and microhabitat
Chitons belonging to the family Acanthochitonidae are commonly found on the top and underside of rocks, rubble and on barnacles on the reef (Gowlett-Holmes 1998). Acanthochitona species are commonly found in the littoral zone, within small tunnels in coraline algal boulders and it is common of a reef crest to be covered in dead coral boulders that are dominated with coralline algae as well as other small algae (Mather and Bennett 1993, Gladfelter 1988, Gowlette-Holmes 2001). Therefore, it is not surprising that Acanthochitona sp. is found in the littoral zone on the reef crest of Heron Island, Australia, in crevices and holes on the underside of coral rubble where a large amount of invertebrate diversity occurs. As Acanthochitona sp. is small, cryptic and seem to be rare (as only two specimens were found after extensive searching in coral rubble while on the island), they may be found living in other areas of the reef at Heron Island that were not investigated.
The colouring of Acanthochitona sp. is very similar to the top side of the coral rubble that is covered in algae and sand and may suggest that this species also lives on the upper side of the coral rubble where they would camouflage easily, however, none were found in this area after investigation at Heron Island. Acanthochitona sp. may move to feed on the algae on the upper side of the coral rubble at night, see Behaviour.
Figure 1: The reef crest (black circle), on the Heron Island Reef, Queensland, Australia, where Acanthochitona sp. is found on the underside of coral rubble.
Figure 2: The underside of coral rubble from the reef crest of the Heron Island Reef, Queensland, Australia, where Acanthochitona sp. inhabits and feeds on algae.
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