Marine Creature of the Month AUG 19

MARINE CREATURE OF THE MONTH

Photo from CNRS News

Common Clownfish

(*cough* actually an anemonefish/false clownfish - it's confusing *cough*)

Kingdom: Animalia

Class: Actinopterygii

Conservation Status: Least Concern (LC)

Thanks to a certain little, animated fish everyone knows what a clownfish is. They are the cute orange and white fish who live in anenan... anememon... Ok, don't hurt yourself kid. I kid, anemones. The common clownfish, which Nemo is based on, is one of thirty species of clownfish or anemonefish, as they are also known. But I am going to look at the common clownfish.

WHERE ARE THEY FOUND?

These little, orange cuties are primarily found in the Eastern Indian Ocean and the Western Pacific Ocean. They can be found in areas around Australia and Southeast Asia too. They live among the reef slopes or sheltered lagoons. These waters tend to be shallow and warm, usually going no deeper than 15m (49ft). And, of course, they set up home in anemones, with which they develop a symbiotic relationship. For the fish, they gain protection from predation due to the anemone's sting which the fish itself is able to resist thanks to a mucus on its scales. What does the anemone get out of this relationship? Having a bright orange fish living in its midst helps acts as a lure to their prey and the clownfish helps the anemone to maintain good health by removing any parasites.

Everyone is happy!

Photo from Legoland Malaysia

WHAT IS THEIR LIFE LIKE?

Clowfish live in hierarchies. The dominant pair get to mate and the lower down the ladder, the more the clownfish get picked on. The juveniles who are new the to anemones tend to be bottom of the pile and are on the receiving end of the higher ranking fishs' aggression. This can lead to the juveniles being kicked out of the anemone and forced to find a new one. (A detail Disney left out!) The size of the group these fish live in depends on the size of the dominant female. It seems this also affects the choice of anemone, but this is still being theorised and argued.

Clownfish grow up to 11cm (4.3inches) but start life in an egg. The females spawn after their courting male has chased them to the anemone - yes, chased - and the male externally fertilises the eggs. Because of this, they are the ones to tend to the eggs - eating any fungi from them or the infertile ones. All clownfish start off male and may become female later in life, if they get the chance to become the dominant lady of the anemone. This is called being a protandrous hermaphrodite. Clownfish change gender when the dominant female is removed - eaten, fished, caught - and the dominant male replaces her, or fills the void.

The females are the ones who rule the roost; using aggression to keep the boys in line and preventing the formation of other females. Next in the hierarchy, the dominant males use aggression to stop the juvenile males from reproducing. It does not sound peachy being a clownfish! They even don't get to eat as much as the dominant fish because they don't have enough energy to forage for food! The bigger fish are stronger and tend to travel further for their food - a tasty diet of algae, copepods, and zooplankton.

Photo from Palawan Divers

WHAT THREATENS THEM?

Being so small, they are not overfished to fill our plates. However, they are at risk from overexploitation. They have always been a feature of tropical fish tanks, their bright colours are appealing and they are useful in research because they are easy to breed. But thanks to Finding Nemo, there has been a massive spike in interest for clownfish creating high demand for their trade, despite the whole film warning against that. Nemo literally gets taken from his father to be featured in a dentist's fish tank and it is portrayed as a bad thing. That's why they spend a whole film on getting him back!

They also face danger from the fact that climate change is destroying reefs. Reef habitats are decreasing thanks to coral bleaching - 15-30% of the world's reefs have been lost in the last generation. At this rate, there will be nowhere left for them to live sooner rather than later.

Photo from The Economist

FUN FACTS

• The increase in clownfish trade thanks to Finding Nemo has been dubbed the "Nemo Effect".
• Their dorsal fins are lined with eleven spines.
• They live, on average, six to eight years in the wild but they have been known to live as long as ten!
• Females lay clutches of up to one thousand eggs.
• Clownfish make up over 40% of the global marine ornamental trade.

Listening to: This is Panic! At The Disco