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Ten described species of sea anemones (Anthozoa: Hexacorallia: Actiniaria) serve as hosts to charismatic clownfishes (or anemonefishes) on coral reefs throughout the tropical Indo-West Pacific. Although not diverse in number, the clownfish-hosting sea anemones have large biogeographic ranges, exhibit extensive intraspecific phenotypic appearances, and have been surrounded by a great deal of historical and contemporary taxonomic and nomenclatural confusion. We believe these factors have created challenges for field scientists making real-time species-level identifications of host sea anemones. Subsequently, a surprising amount of peer-reviewed clownfish literature never accounts for the host sea anemone, omitting critical data for understanding the symbiosis ecologically and evolutionarily. Here, we leverage the revolution that has taken place in the realm of digital underwater photography over the past 30 years to provide an updated, practical field guide for the clownfish-hosting sea anemones. First however, we review and revise the nomenclature for each species to better reflect valid changes that were made in the historical literature but never broadly adopted. Next, we demonstrate that machine learning algorithms may be of limited use for automating sea anemone species IDs from digital photographs alone—highlighting the importance of organismal expertise for identifying these animals. Finally, we present high-resolution digital photographs that encompass much of the intraspecific phenotypic variation encountered underwater, discuss important characteristics useful for field IDs, and provide updated range maps for each species to better reflect the known biogeographic range of each host anemone. We hope the increased confidence in field identification provided by this guide will result in more papers incorporating the sea anemone host data into research frameworks and subsequent publications.
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Clownfish hosting anemones (Anthozoa, Actiniaria) of the Red Sea: new associations and distributions, historical misidentifications, and morphological variability
Abstract BackgroundThe Red Sea contains thousands of kilometers of fringing reef systems inhabited by clownfish and sea anemones, yet there is no consensus regarding the diversity of host anemone species that inhabit this region. We sought to clarify a historical record and recent literature sources that disagree on the diversity of host anemone species in the Red Sea, which contains one endemic anemonefish,Amphiprion bicinctusRüppell 1830. ResultsWe conducted 73 surveys spanning ~ 1600 km of coastline from the northern Saudi Arabian Red Sea to the Gulf of Aden and encountered seven species of host anemones, six of which hostedA. bicinctus.We revise the list of symbionts forA. bicinctusto includeStichodactyla haddoni(Saville-Kent, 1893) andStichodactyla mertensiiBrandt, 1835 which were both observed in multiple regions. We describe Red Sea phenotypic variability inHeteractis crispa(Hemprich & Ehrenberg in Ehrenberg, 1834) andHeteractis aurora(Quoy & Gaimard, 1833), which may indicate that these species hybridize in this region. We did not encounterStichodactyla gigantea(Forsskål, 1775), although the Red Sea is the type locality for this species. Further, a thorough review of peer-reviewed literature, occurrence records, and misidentified basis of record reports dating back to the early twentieth century indicate that it is unlikely thatS. giganteaoccurs in the Red Sea. ConclusionsIn sum, we present a new guide for the host anemones of the Red Sea, revise the host specificity ofA. bicinctus,and question whetherS. giganteaoccurs in the central and western Indian Ocean.
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- Award ID(s):
- 2205567
- PAR ID:
- 10360347
- Publisher / Repository:
- Springer Science + Business Media
- Date Published:
- Journal Name:
- Marine Biodiversity Records
- Volume:
- 14
- Issue:
- 1
- ISSN:
- 1755-2672
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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