Stealthy Reef Fish in the ‘Twilight Zone’

Research is showing that many types of reef fish have the ability to swim at greater depths than previously thought. Scientists have been taking a closer look at different coral reef fish species and analyzing the physiology to get a better understanding of their marine capabilities.

FISH101 coral fish

Coral reefs are generally though to be in shallow sunlit waters and display a variety of fish, but studies are showing that deep water reefs in the ‘Twilight Zone’ of 50-150 m deep are also capable of providing a diverse and unique community of colorful fish.  Dr. Tom Bridge from the  ARC Centre of Excellence for Coral Reef Studies at James Cook University has been researching the physiology of these fish and have found that the tail shape of some fish can help predict whether they can live in a wide range of water depths.

FISH101 twilight zone

Dr. Bridge and Dr.  Osmar Luiz from Macquarie University believe that fish with a more forked tailed shape are able to swim faster and perhaps more silently through the water. Stealth swimming in the greater depths of the ocean is important because deep water habitats provide less light transmittance, less wave energy and the species rely on sensing water pressure and motion changes to help catch prey and avoiding predators. The forked tail is thought to move the fish through the water smoothly without causing major water displacement and allows these coral fish to migrate between both shallow and deep waters.

Understanding this feature can help scientists predict which species is less vulnerable to natural disturbances like cyclones and coral bleaching and scientists are currently working to gain a better understanding of what exactly it is about the forked tail that gives these fish this advantage in deep water.

FISH101 twilight 2

Works Cited:

ARC Centre of Excellence for Coral Reef Studies. (2016, January 20). ‘Twilight zone’ fish swim silently with forked tails. ScienceDaily. Retrieved January 27, 2016 from

Tom C. L. Bridge, Osmar J. Luiz, Richard R. Coleman, Corinne N. Kane, Randall K. Kosaki. Ecological and morphological traits predict depth-generalist fishes on coral reefs. Proceedings of the Royal Society B: Biological Sciences, 2016; 283 (1823): 20152332 DOI:10.1098/rspb.2015.2332

2 thoughts on “Stealthy Reef Fish in the ‘Twilight Zone’”

  1. This is very interesting! It’s amazing how much mankind does not know about the ocean and the life that lives there. I did my case study on adaptation as well.

  2. I learnt something today! Thank you! It does make sense doesn’t it – the more streamlined a fish, the less “noise” or disturbance it will create in a fluid and the smaller the probability of detection — it left me wanting to find out more.. Good article!!

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