Male/Female or what?

Clownfish or anemonefish, Amphiprion sp are fishes from the subfamily Amphiprioninae in the family Pomacentridae.

Many people do not kclownfishnow that clownfish are actually transsexuals! Clownfish are hermaphrodites that have both female and male gonads. Once the clownfish are hatched, the female gonads are suppressed and so all clownfish start life as males, no females.

After the early part of their lifecycle, upon finding a suitable host sea anemone, clownfish will settle down on it. The clownfish will gently touches the anemone’s tentacles over a period of several hours or days, until they form a layer of mucus that is resistant to the stings. Usually, a small group of clownfish live in one large sea anemone. And in each sea anemone, there exists a strict hierarchical system between the clownfishes. The highest rank is the female breeder, following next is the male which mate with the female breeder. Only one male clownfish ( which is ranked number two) mate with the female breeder. And at the bottom of the ranks will be up to four smaller, non breeding clownfishes.

clownfish on flickr

Ocellaris clownfish HD video at Haus des Meeres on Flickr – Photo Sharing!

And when the female clownfish die, her mate changes sex and becomes female! At the same time, the largest of the non-breeding clownfish becomes the functioning male. Other fishes also moved up a rank. Another interesting obervations is that clownfish regulate their size in order to remain in the community. Each clownfish will keep its size smaller than the clownfish directly above its rank. Clownfish that grow bigger than clownfish above its rank could be rejected by the community. This adaptation of clownfish ensure continuous reproduction.


” Social hierarchies: Size and growth modification in clownfish,” by  Peter Buston. Nature 424, 145-146, 10 July 2003 URL:

(accessed on 07/04/2010)
“Nemo puts clownfish in spotlight,” by Ann Kellan. CNN, Monday, August 4, 2003 URL:

(accessed on 07/04/2010)
“Ocellaris clownfish HD video at Haus des Meeres” by john.nousis. flickr from yahoo URL:

(accessed on 07/04/2010)

“Splash Zone Coral Reef Animals” by montereybayaquarium      URL:

(accessed on 07/04/2010)

“Cave under Ras Muhammad” by Leigh Cunningham. X-ray MAG57,58 ,2008   URL:

(accessed on 07/04/2010)

“Clownfish” by beest. flickr from yahoo URL:

(accessed on 07/04/2010)

“Playing Possum”



Remember the two adorable and hilarious creatures from Ice Age 2: The Meltdown, Crash and Eddie? They are the twin opossum brothers who appeared in Ice Age 2 and spend most of the time attempting dangerous stunts such as buggy jumping above lava pits, and being catapulted through the air by a tree.

In reality, Opossums, Didelphia Virginiana, are in fact not so adorable, and are rather unglamorous creatures. It has big, black eyes, a pale pointy face, and a hairless tail, resembling a rat. They are nocturnal creatures and the only marsupial (pouched mammal) that can be found in North America. They are also Earth’s oldest surviving mammal family, which explains the presence of the opossum characters in the Ice Age movie. It lived during the age of dinosaurs and fossil remains of these mammals have been found from a whopping 70 million years ago!

Today, opossums are known to be scavengers as they often enter human homes to raid garbage cans and dumpsters. They can eat almost anything, ranging from grass and nuts to worms, snakes and even chickens! This is rather amazing given its small size in comparison to the snakes and chickens.

Below is a video on the most famous and unique behavior of an opossum, please click on play and enjoy!



As you can see from this really amusing video and photo above, “playing possum” refers to the opossum faking death whenever it is being threatened by potential danger possibly caused by animals such as dogs, foxes or bobcats!

During the act of “playing possum,” when the opossum senses danger, it will flop down on its side, go limp and even begin to drool. Its eyes will turn glassy and motionless, with its tongue falling out of its mouth. This will mislead the potential predator into thinking that it is already dead, so that the potential predator will lose interest in the “dead” opossum, giving the opossum a chance to escape unscathed. As you can see from the video above, the dog looked really confused at the opossum’s motionless state but walked away after awhile, thus achieving the opossum’s objective!

However, it is interesting to note that this form of behavior by the opossum is entirely involuntarily as it serves to provide a form of protection for the animal. On the other hand, this playing dead behavior also makes the opossums vulnerable. When drivers on the roads see the limp opossums in the middle of the road, they will not bother to swerve under the assumption that they are really dead.

Unfortunately, these comical animals can’t be found in Singapore. So, if you happen to go to the United States and Canada, do look out for these “dead” creatures so as to avoid potential roadkills!


“Top 10 Animal Adaptations: Creatures Countdowns: Animal Planet”  by Animal Planet. URL: (accessed on 5 Arpil 2010).

“Opossums, Opossum Pictures, Opossum Facts” by National Geographic. URL: (accessed on 5 April 2010).

Our ‘Sleep-Talking’ Dogs

Ever freaked out on your canine when she starts yelping while supposedly asleep? Or her legs starts scurrying almost mid-air with her whiskers twitching and nose sniffing as if nothingness with her eyes closed? Apparently, our domesticated canines, otherwise known as Canis familiaris (Discovery Cove, Animal Bytes, Domestic Dogs, 2010), might experience dreams just as we do! Watch the following video for some comic (albeit rather painful) relief:


Dreams occur during the Rapid Eye Movement (REM) sleep phase. The function of dreams in the Homo sapiens (humans) is that it helps us to consolidate memory traces from our waking hours via certain processes which occur in the hippocampus (a region of the brain that has been implicated in memory processes), strengthening processes of connections between regions of the brain (Macquet et. al., 2000). According to an article done by Firth, Perry, and Lumer (1999), when electroencephalography (EEG) readings were taken during the mammal’s sleep phases, “they show REM sleep characterized by a ‘waking’ pattern of EEG, rapid eye movements and inhibited muscle tone” (Firth, Perry, and Lumer, The neural correlates of conscious experience: an experimental framework, 1999). Simply put – animals appear to experience REM sleep phases as humans do.

dog dreams

(“Dog Dreams” by bobmarley753,

…Do they, really?

We observe our pet dogs letting out muffled yelps and see their muscles twitch, and scientists have recorded EEG readings that are akin to REM sleep. But these do not necessarily mean that our dogs actually experience the ‘mental representations’ of dreams like we do. Perhaps there could be an experiment run using Positron Emission Tomography (PET) which shows the areas of the brain activated whenever there is neural activity – so perhaps, the evidence might be more conclusive with tests run on mammals during their REM sleep phases, measuring both EEG and PET simultaneously. Should it show that the visual areas of the brain are activated in the animals during their REM sleep like we do when we dream, then perhaps animals do really dream with the mental representations as we do.

Thus far in my research attempts, I have not found an article measuring both EEG patterns and PET readings for animals’ dreams. But having lived with my dog for almost 11 years and catching moments where she sometimes seem to be happily scurrying and ‘sniffing’ while asleep – and sometimes – barking herself awake silly, I like to think that she is dreaming of runs within a field and chasing some rodent of sorts (my dog is a Smooth Fox Terrier – a hunting breed, after all). 🙂

Two of a Kind(“Two of a Kind” by schilfregen,


“Bizkit the Sleep Walking Dog” by MarinaHD2001. YouTube Channel, 10 February 2009. URL: (accessed on 01 April 2010).

“Do Dogs Dream?” by Niki. AssociatedContent, 13 June 2007. URL: (accessed on 01 April 2010).

“Dog Dreams” bybobmarley753. Flickr, 26 September 2006. URL: (accessed on 02 April 2010).

“Domestic Dog” by Discovery Cove. DiscoveryCove, URL: (accessed on 01 April 2010).

Maquet P., Laureys, S., Peigneux, P., Fuchs, S., Petiau, C., Phillips, C., Aerts, J., Fiore, G.D., Degueldre, C., Meulemans, T., Luxen, A., Franck, G., Linden, M.V.D, Smith, C., Cleeremans, A., 2000. Experience-dependent changes in cerebral activation during human REM sleep. Nature Neuroscience, Volume 3 no 8: 831-836.

“Two of a kind” by schilfregen. Flickr, 04 October 2009. URL: (accessed on 02 April 2010).