Spiny Puller, Acanthochromis polyacanthus (Bleeker, 1855)

Introduction

The Spiny Puller can be separated from other Indo-Pacific Damselfishes by its high number of dorsal fin spines (17 vs. 8-15, commonly 13-14). Juveniles nip mucus off the sides of their parents in a behaviour known as 'glancing'.

Identification

The Spiny Puller can be separated from other Indo-Pacific Damselfishes by its high number of dorsal fin spines (17 vs. 8-15, commonly 13-14).

Its colouration is variable. On the southern Great Barrier Reef it is bluish-grey. Further north it is brown anteriorly and white posteriorly. Some Coral Sea individuals are entirely white.

Habitat

The Spiny Puller occurs in coral reef and inshore waters.

Distribution

The species occurs in the tropical Western Pacific region. In Australia it is known from the north-western coast of Western Australia and the entire length of the Great Barrier Reef, Queensland.

The map below shows the Australian distribution of the species based on public sightings and specimens in Australian Museums. Click on the map for detailed information. Source: Atlas of Living Australia.

Feeding and diet

Adults feed on plankton.

Juvenile Spiny Pullers show a strange behaviour known as 'glancing', during which small amounts of mucus may be ingested from the sides of their parents. Kavanagh (1998) states that "I interpret the results of this study as evidence tht the current function of glancing in Acanthochromis is not merely to provide additional nutrition. Approximately six bites per day of mucus seems little caloric incentive to maintain this behavior when other foods seem easily available. The question remains, then, what is the function of the behavioral interaction?. Because ingestion does not occur during at least some of the glances, transfer of some substance from parent to juvenile occurs. Transfer of small quantities of vital nutrients or hormones during glancing could encourage faster growth or development - possibly an advantage on the reef. This seems a good avenue for further investigation."

Life history cycle

The species is unusual because it is one of only three pomacentrid species that do not have planktonic larvae. The larvae of all three species stay with the parents after hatching. The other two species are the Azure Damsel, Altrichthys azurelineatus and Altrichthys curatus (no common name), a species described in 1999 by Dr Gerald R. Allen (see References).

References

• Allen, G.R. 1991. Damselfishes of the World. Mergus. Pp. 271.
• Allen, G.R. 1999. Altrichthys, a new genus of Damselfish (Pomacentridae) from Philippine Seas with Description of a new species. Revue fr. Aquariol. 26(1999): 23-28.
• Hoese, D.F., Bray, D.J., Paxton, J.R. & G.R. Allen. 2006. Fishes. in Beesley, P.L. & A. Wells. (eds) Zoological Catalogue of Australia. Volume 35. ABRS & CSIRO Publishing: Australia. parts 1-3, pages 1-2178.
• Kavanagh, K. 1998. Notes on the frequency and function of glancing behaviour in juvenile Acanthochromis (Pomacentridae). Copeia. 2: 493-496.
• Leis, J.M. & B.M. Carson-Ewart. (editors). 2000. The larvae of Indo-Pacific coastal fishes. An identification guide to marine fish larvae. Brill, Leiden. Pp. 870.
• Randall, J.E., Allen, G.R. & R.C. Steene. 1997. Fishes of the Great Barrier Reef and Coral Sea. Crawford House Press. Pp. 557.