Coral-eating flatworm gets a name

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Scientists have named the coral-eating flatworm that we reported on last year in PFK.

The Acropora-eating flatworm (AEFW) eats a number of species of Acropora in aquaria and if not removed can eat entire colonies of coral.

The new species has been named Amakusaplana acroporae and belongs to the family Prosthiostomidae.

So far the flatworm has only been reported in aquaria with specimens reported from a number of private and public aquaria throughout the United States. Worryingly, there have also been anecdotal reports of the worm being found on coral in Germany and the UK although these have not been confirmed. The status of the flatworm is unknown in the wild but is thought perhaps to originate from the Indo-Pacific as these are the acroporids on which it is found.

The polyclad flatworms are 6–17mm long and 3–10mm wide with brown markings on a white background. Study of the life cycle of the flatworm has discovered that adults lay multiple clutches of eggs, each batch contains 20-26 egg capsules and each egg capsule contains 3-7 embryos.

Although hatchlings are able to swim they settle very quickly which together with their fecundity, camouflaged appearance and absence of natural predators means that they can have devastating effects on coral in aquaria.

Many acroporids are now listed as either Vulnerable or Threatened in the wild. This study has particular relevance due to the importance of aquarium reared acroporids to the sustainable hobby trade, education and reef restoration efforts.

First signs of coral affected by A. acroporae are feeding scars on the coral tissue and egg batches on the coral skeleton. Currently recommended treatments to reduce A. acroporae numbers include spraying freshwater onto the corals to loosen adults, the introduction of wrasse (e.g. Halichoeres spp.) to prey on loosened adults in the water column and the removal of egg capsules.

For further information see: Taxonomy and life history of the Acropora-eating flatworm Amakusaplana acroporae nov. sp. (Polycladida: Prosthiostomidae) K. A. Rawlinson, J. A. Gillis, R. E. Billings Jr, E. H. Borneman 2011 Coral Reefs DOI 10.1007/s00338-011-0745-3.