''Stichodactyla mertensii'', commonly known as Mertens' carpet sea anemone, is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

sea anemone Sea anemones ( ) are a group of predation, predatory marine invertebrates constituting the order (biology), order Actiniaria. Because of their colourful appearance, they are named after the ''Anemone'', a terrestrial flowering plant. Sea anemone ...

s in the family Stichodactylidae. It is regarded as the largest sea anemone with a diameter of over , the next largest being '' Heteractis magnifica'', which has longer tentacles. This species has an oral disc that can be described as more ovoid than circular that contours to the surrounding substrate and is attached to the substrate by adhesive verrucae, which are wart-like projections. Its blunt or pointed tentacles are uniformly shaped, and are only about long. It contains obligate symbiotic zooxanthellae, and is a host to around half the species of anemonefish and one

damselfish Damselfish are those fish within the subfamilies Abudefdufinae, Chrominae, Lepidozyginae, Pomacentrinae, and Stegastinae within the family Pomacentridae. Most species within this group are relatively small, although the four largest speci ...

, '' Dascyllus trimaculatus''.

Distribution

''S. mertensii'' is found on rocky or coral substrate and is widespread throughout the tropical and subtropical waters of the

Hawaii Hawaii ( ; ) is an island U.S. state, state of the United States, in the Pacific Ocean about southwest of the U.S. mainland. One of the two Non-contiguous United States, non-contiguous U.S. states (along with Alaska), it is the only sta ...

, USA,

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

Indo-Pacific The Indo-Pacific is a vast biogeographic region of Earth. In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the ...

area. from

Mauritius Mauritius, officially the Republic of Mauritius, is an island country in the Indian Ocean, about off the southeastern coast of East Africa, east of Madagascar. It includes the main island (also called Mauritius), as well as Rodrigues, Ag ...

Fiji Fiji, officially the Republic of Fiji, is an island country in Melanesia, part of Oceania in the South Pacific Ocean. It lies about north-northeast of New Zealand. Fiji consists of an archipelago of more than 330 islands—of which about ...

and from the

Ryukyu Islands The , also known as the or the , are a chain of Japanese islands that stretch southwest from Kyushu to Geography of Taiwan, Taiwan: the Ryukyu Islands are divided into the Satsunan Islands (Ōsumi Islands, Ōsumi, Tokara Islands, Tokara and A ...

of southern Japan to Australia. While this species can be confused with '' Stichodactyla gigantea'' and '' S. haddoni'', they are most easily distinguished by habitat since the former two prefer sand while ''S. mertensii'' prefers rocky or coral substrate.

Biology

The anemonefish generally said to be hosted by ''S. mertensii'' are: Other anemonefish said to be hosted by ''S. mertensii'' are: The relationship between anemonefish and their host sea anemones is highly nested in structure. With at least 13 species of hosted anemonefish, ''S. mertensii'' is highly generalist, and appears to be a preferred host. ''A. akallopisos'' is the only anemonefish in the

Comoro Islands The Comoro Islands are a group of volcanic islands in the Mozambique Channel, an arm of the Indian Ocean lying between Madagascar and the African mainland. Three of the islands form the Union of the Comoros, a sovereign nation, while Mayotte bel ...

and is hosted by '' Heteractis magnifica'' and ''S. mertensii''. It appears that in the

Seychelles Seychelles (, ; ), officially the Republic of Seychelles (; Seychellois Creole: ), is an island country and archipelagic state consisting of 155 islands (as per the Constitution) in the Indian Ocean. Its capital and largest city, Victoria, ...

that ''A. fuscocaudatus'' displaces ''A. akallopisos'' from ''S. mertensii'' while in the

Maldives The Maldives, officially the Republic of Maldives, and historically known as the Maldive Islands, is an Archipelagic state, archipelagic country in South Asia located in the Indian Ocean. The Maldives is southwest of Sri Lanka and India, abou ...

''A. akallopisos'' is displaced from ''S. mertensii'' by ''A. clarkii'', as in both locations ''A. akallopisos'' is only hosted by ''H. magnifica''. There are 2 specialist anemonefish that are only found with ''S. mertensii'', ''A. fuscocaudatus'' and ''A. latifasciatus''. Recently, '' Amphiprion clarkii'' and '' Amphiprion sandaracinos'' were observed to coexist within one host anemone of ''Stichodactyla mertensii''. A. clarkii was not aggressive towards the A. sandaracinos but was aggressive towards all fish approaching the anemone. The anemonefish didn't divide the host into separate territories.

Anemonefish color variations

Some species of anemonefish, including ''A. chrysogaster'', ''A. chrysopterus'', ''A. clarkii'', ''A. percula'' and ''A. tricinctus'' have a melanistic variation when associated with anemone of the genus ''Stichodactyla''. The change in body and or fin color from orange to black can occur within hours when transferred to the anemone. The fish then changes back from black to orange when removed from the host, although the change back takes longer. Why this occurs and its benefits to either partner are unknown. Other species do not show any such variation including ''A. akallopisos'', ''A. akindynos'', ''A. allardi'', ''A. bicinctus'', ''A. fuscocaudatus'', ''A. latifasciatus'', ''A. leucokranos'' and ''A. sandaracinos''. There is a black variation of ''A. ocellaris'', however it is not known whether this is associated with any specific anemone. Image:Amphiprion clarkii.jpg, ''A. clarkii'' in a 'normal' color Image:Amphiprion clarkii Thailand.jpg, ''A. clarkii'' showing a melanistic variation

Notes

References

External links

* * {{Taxonbar, from=Q1508080 Stichodactylidae Animals described in 1835