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1, Jun, 2011

Western Clownfish – Amphiprion Ocellaris

Posted in Fish Finder, Latest News, Marine Life by magnus

Western Clownfish Facts:

  • Clownfish actually belong to a group of fish known as Anemonefish, which in turn belong to the family; Damsel fish
  • There are approximately 28 recognised species of Anemonefish
  • The Clownfish gets its name both from its bright, clown-like, colourful markings and from the funny way it moves or ‘clowns’ around
  • The Western Clownfish is actually the ‘False Percula Clownfish’ with the True Percula Clownfish’ being the very similar Orange Clownfish (Amphiprion percula) – the only difference between these two species is that the Orange Clownfish usually has ten dorsal spines, while the Western Clownfish has eleven.
  • Clownfish are said to live for around six-eight years
  • In the wild, all Anemonefish (and therefore Clownfish) live in a symbiotic relationship with their host anemone
  • The stinging arms of the anemone protects the Anemonefish from predators
  • Anemonfish are protected from the stinging tentacles of the anemone by an unusually thick mucus membrane which secretes a chemical that makes them undetectable to the anemone’s tentacles. This mucous coat is developed during multiple interactions with the host anemone. The anemone is fooled into feeling like it’s touching itself when it touches the slime of the clownfish and so does not sting
  • Anemones are actually flesh-eating animals that look like plants
  • Clownfish predominantly live off eating the left overs from their anemone’s carnivorous diet
  • By swimming in their cute, waddley way, Anemonefish create water circulation that is beneficial for the anemone
  • Being relatively poor swimmers, they rarely go farther than a few inches from their host anemone. This is due, in part to their inability to out-swim or escape predators, but also to their fear of losing the anemone to another anemone fish
  • Anemonefish aggressively protect their anemone from intruders and are known to chase off creatures as large as turtles or even divers! (beware – they have been known to bite divers that get too close)
  • Anemonefish are born with both male and female reproductive organs and can change sex as they mature
  • In a family there is strict hierarchy of dominance where the female is the largest and most aggressive in a group
  • There is only one sexually mature male in a group. This male lives monogamously with the female in the group and the rest are non-reproductive, smaller males
  • If the female dies, the sexually mature male will change sex and become the dominant female. The second largest male will then move up in hierarchy and become sexually mature (as a male)
  • The female lays eggs close to the anemone and the male guards them for 5-7 days until they hatch
  • You can find Western Clown Anemonefish (Amphiprion ocellaris), Skunk Anemonefish (Amphiprion perideraion) and Clarke’s Anemonefish (Amphiprion clarkii) on all dive sites around Ko Lanta. The Tomato Anemonefish (Amphiprion frenatus) can be seen at the Ko Phi Phi dives sites



All Anemonefish live in a symbiotic relationship with their host anemone



Western clownfish (more popularly known as Nemo) are a surprisingly small species of fish. Many divers remarks that ‘they are far smaller than they had imagined’, upon seeing them for the first time. They can grow up to 8cm (3 inches) in length, but are often smaller than this.

Due to their small size, clownfish are preyed upon by a number of predators but use the safety and protection of their stinging host anemone to keep out of harms way.

During day-to-day life on a coral reef, clownfish are probably amongst the least-snacked-on small fish, as they are relatively difficult to catch, as they dart about the waving, stinging tendrals of their sea anemone.

Large species of fish, sharks and eels are the main predators of the clown fish in the water but the human is the biggest overall threat to the clownfish as they are caught to keep in tanks and aquariums.



Two Western Clownfish in their Anemone



A 2-Way Relationship

Clownfish live in a mutually beneficial, symbiotic relationship with their host anemone. From the clownfish’s perspective, this is good as the anemone provides shelter and protection from predators and is a good food source, in the form of leftovers from any fish the anemone devours.

In turn, the clownfish helps its host by luring-in unsuspecting prey. The clownfish attracts other fish and shrimps into the deceptively mesmerising tentacles of the sea anemone, by showing off its bright colors. The anemone quickly ensnares any creature that strays too close, by hugging it tightly and killing it with poison released from it’s tentacles. Once stilled, the prey is ingested and devoured whole into its large central mouth.

The clownfish generally likes to keep its home anemone nice and clean, eating away any dead tentacles and creating a good circulation of water which is beneficial for the anemone. The feces of the clownfish also provides specialist nutrients to the sea anemone.

Anemonefish have adapted to be able to safely live in the stinging arms of an anemone. They have developed their own, unusually thick protective, mucus membrane which secretes a chemical that makes the fish undetectable to the anemone’s tentacles. The anemone is fooled into feeling like it’s touching itself when it touches the slimy mucus of the clownfish and so does not release it’s sting.

Anemonefish in general are fiercely territorial. They protect their host anemone so aggressively that they will even chase away marine animals that are many times larger than themselves. They are known to chase off creatures as large as turtles or even divers!

It does strike me that the clownfish does rather better out of this deal than the anemone – no wonder they put up a fight to hold on to it!



A family group of Western Clownfish



The Complicated Sex-Life of a Clownfish

Clownfish tend to live in a family group within an anemone which consists of a sexually mature male and female and a number of younger male clownfish.

Anemone clownfish are protandrous hermaphrodites, which means they start out their life as a male and later they can change to become female, developing female reproductive organs when required. (Technically they are born with both male and female sex organs which both lie dormant until being needed). When the female in the group dies, the dominant male will become female and the next largest male, will develop functioning male sex organs to replace the male who is now female – confusing!

Female clownfish lay thousands of eggs at a time and usually try to find a flat surface close to their host anemone on which to lay them. Clownfish lay their eggs around the full moon and the male clownfish guards the eggs until they hatch just over a week later.

Despite the rising levels of pollution in the world’s oceans and destruction of the habitats on the ocean floor, clownfish are not considered to be an endangered species, mainly because they lay so many eggs at a time. Even though not all of the clown fish eggs will hatch, a vast number of clownfish fry hatch in every spawn meaning that clownfish numbers remain high in the wild.

Divers with a Western Clownfish - Amphiprion ocellaris



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