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116. Mauritian Anemonefish (Amphiprion chrysogaster) and colour change



Subject:

The Mauritian Anemonefish (Amphiprion chrysogaster) is endemic to the Mascareignes islands, a group of islands in the southern Indian Ocean comprised of Réunion, Mauritius, and Rodrigues. Although very common in Mauritian waters, it is rarer on the reefs of its sister island, Réunion, and probably absent in Rodrigues.


Anemonefish are thanks to their colourful appearance also called clownfish, they are members of the subfamily Amphiprioninae in the family of the damsels, Pomacentridae. It is one of thirty species of anemonefish that form a symbiotic mutualistic relationship with anemones. All members of this group belong to the subfamily Amphiprioninae in the family of damsels Pomacentridae.


The Mauritian Anemonefish bears the typical anatomical characteristics for this subfamily; a typical small oval damselfish shape, yellow/orange/red/black coloured skin and white lines, bars, and/or markings. The colours of a single species of anemonefish vary depending on its distribution, sex, age, and host anemone. However, the juveniles of this particular anemonefish are always orange coloured with white bars, but at a later stage in life, they change colour depending on their host anemone.


When an individual lives in a Magnificent Sea Anemone (Heteractis magnifica), like in this clip, the orange of the body (not their fins) starts darkening to brown. When the fish sets out to live in more toxic carpet anemones (Genus Stichodactyla), the orange body changes to black. Why this happens is not fully understood, but different studies suggest that it may have something to do with the anemonefish’s stress response to the greater toxicity of the giant carpet anemone. Research states that, in general, the anemonefish’s thyroid hormone levels were much higher in those living in the giant carpet anemone. These hormones play an important role in the development of the fish’s pigment cells.


Other species of anemonefish may develop a similar response to the toxicity of the host anemone regarding the development of their white bars in juveniles; the white bars appear faster (earlier in life) on individuals living in giant carpet anemones. Additionally, the form and shape of the white bars and lines on the anemonefish have something to do with the type of anemone and length and thickness of the anemone’s tentacles in which these little damsels live.


Technique:

For this underwater video clip, we used split screens. This editing technique allows us to show different parts of the video simultaneously to create an overall impression. It also aids in isolating the good side of shots that were not overall good enough to broadcast. Because more images are shown in a shorter time, the total length of a video can be shortened significantly, which can be crucial to retain the viewer’s attention.


In real documentaries, it can be used to tell both sides of a common story, for example, prey and predator. Here, both individuals are filmed and projected on half a screen to come together on a single whole screen at a later moment in time where the actual predation takes place.


Filming location:

This short underwater videoclip has been filmed in Mauritius 🇲🇺


More about this topic:

For a more in-depth description about the anemonefish sex change please visit vlog posts 156: https://www.beyondscuba.com/post/mauritian-anemonefish-a-chrysogaster-sex-change


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