Saving the best for last: Mating rituals of the carribean reef squid



a pair of squids mating

a pair of squids mating



Imagine the idea of remaining celibate your entire existence right until the last day of your life where you engage in a massive orgy of sorts. Intrigueing? The carribean reef squid(Sepioteuthis sepioidea)does just that! A torpedo-shaped squid that averages in length at about 20cm, belongs to the Cephalopod family and can be found in the shallow reefs of the carribean sea in schools of 4-30. If you think this is going to be just another boring entry extolling the biological traits of this cephalopod– think again! One of the most interesting aspects about this squid is that, like other cephalopods, its is semelparous. Semelparous organisms reproduce only once in their lifetime, thus explaining the title of this entry you are reading. The crux of this entry, will thus focus on the mating ritual of the carribean reef squid.For the most part of their lifespan, the Sepioteuthis sepioidea are perfectly content having no sex at all, swimming around in schools in the day and hunting alone for food at night, consuming up to 60% of their body mass with their voracious appetites. However, this all changes as they approach the last weeks of their lifespan, and their voracious appetite for food translates into an overwhelming sex drive. During mating season, these squids are known to mate for hours at a time, and their mating ritual precedes a courtship process, which can be a very interesting sight indeed. During the courtship ritual the Sepioteuthis sepioidea change their colouration, shape and texture via nervous control of  their chromatophores. Males do this to enhance their attractiveness to the opposite sex whereas females do so to indicate their interest.



Male squids sparring, sporting a spotted mantle, a sign of aggression and competition

Male squids sparring, sporting a spotted mantle, a sign of aggression and competition




In the first stage of the mating game, a male will compete with about 4 other squids. Upon emerging victorious, it would then approach a female. One interesting effect about these male squids to note is that unlike our human counterparts, these reef squids are actually attracted to females of larger proportions! They will however, eventually settle with a same-sized female. The game begins when the male “flashes” and pulsates, gently sticking its tentacles onto her skin just below the eyes. A willing female often turns pale and the pair swim fairly quickly side-by-side in a rocking motion. Then he darts around in front of her and sticks the spermatophores in place. Females play games too! A female squid might play “hard to get” by putting an agonistic pattern of rough vertical zebra stripes on her skin and swimming away quickly. More often than not, this is being done to assess the male squid’s agility in “chasing” her. In the meantime, other male contenders might intercept by displaying neat zebra stripes across their mantle. If the male proves worthy, he will then be allowed to inseminate a sticky cluster of sperm into her, displaying a pulsating pattern, like a victory routine.

courting pair squids                                                 Picture depicts a pair of courting squids


All good things must come to an end however, and this vibrant display of courtship and vigour has to eventually end too. The impregnated female squid searches for little protected cracks and crevices in the reefs. She squeezes her way in and moves eggs out past the spermatophoric gland to fertilize them, gives them a gel coat and attach them in small clusters. The female turns into a dark brown shade whilst doing so. Shortly after, the female dies. The male squid also dies, becoming frail and susceptible to predator fish, such as tuna and yellowtail. Nevertheless, this intricate display of colour and marine art is indeed a sight to behold. If you happen to be snorkeling around shallow Caribbean waters in the morning, do look out for the Caribbean reef squid. If you are lucky enough you’d be able to witness first-hand this wondrous spectacle of Mother Nature!

 If you wish to view videos of the Sepioteuthis sepioidea, please click on the following link : 

 Done by: Melissa Lim Ying Pei, U098708N


Second source- 

Science Direct- Encyclopedia of Ocean Sciences: Cephalods

other references:

The Lion King: Why do hyenas laugh?

When we talk about the movie, ‘The Lion King’, we often think about Simba the lion, Timon the meerkat, Pumbaa the warthog and the bad guys, the laughing hyenas.

So what is a hyena and do hyenas really laugh as depicted in the movie?

The Hyenas shown in the movie are the Spotted Hyenas, Crocuta crocuta, which belong to the family of Hyaenidae. Spotted Hyenas live in a clan, which is led by a single alpha-female and a clan can consist up to 80 individuals.

Hyenas’ laugh is to depict the hyenas’ age and social status. The giggles that the hyenas give out differ in pitch and variation in the frequency of notes.

Pitch of the giggle reveals the hyenas’ age. Before hyenas reach maturity of three years of age, it is considered as a young hyena. And young hyenas tend to have a higher pitched giggle.

On the other hand, variation in the frequency of notes can give information about the hyenas’ social status, alpha-dominant females or subordinate females. Subordinate females’ calls tend to be more inconsistent while dominant females tend to not giggle too much.

The Spotted Hyenas, also famously known as the Laughing Hyenas, really do laugh! So when you encounter a laughing hyena next time, you should be able to know what the hyena is laughing about!

Links To Secondary Source:

The journal of the Acoustical Society of American, Volume 125, Issue 4, pp. 2709 (April 2009): The hyena’s laugh as a multi-informative signal (A). Retrieved from Accessed on 8 April 2010


Google image, The Lion King. Retrieved from Accessed on 8 April 2010


Wikipedia, the free encyclopedia, Spotted Hyena. Retrieved from Accessed on 8 April 2010

“Hyena giggles no laughing matter” by Jason Palmer, 12 May 2009. Accessed on 8 April 2010

Invasion of the Red Crabs!

Christmas Island Crab Invasion

Whilst some species of crabs may seem common on our regular seafood dinner table, this particular species may not be as they are toxic to human beings. The red crabs, Gecarcoidea natalis, are endemic to the forests of Christmas Island, located in north-west of Australia in the Indian Ocean. Their mating season occurs annually during the monsoon season, where they have to migrate to the coast for breeding.

At the coast, the male crab would have to fight with other males to gain the rights to dig a burrow in which mating occurs. This is a demonstration of greater fitness than rivals. The female will be left in the burrow where she brood the eggs in a pouch on her abdomen. The female will release her eggs into the sea after a lapse of 12 days. These eggs hatch immediately into tiny larvae.

In migrating to the coast from the forests, the crabs have to go through obstacles like roads, where vehicles are prevalent. This poses a threat to the crabs as they face the danger of getting crushed by oncoming vehicles. In order to protect the red crabs from getting crushed on the roads by vehicles during the migration period, the local authorities have closed a few roads.

In addition, the migration of the red crabs has become such a phenomenon that it is now used to attract tourists as this spectacular sight is hard to find in other countries.


  1. “Christmas Island Crab,” by BBC Science and Nature, July 2005. URL: on 5 Apr 2010).  
  2.  “Science Screen Report: The Amazing Red Crab of Christmas Island !,” by Allegrosjf YouTube Channel, 25 September 2009 . URL: (accessed on 5 Apr 2010)
  3. “Red Crabs,” by Environment Australia. URL: on 6 Apr 2010)
  4. Agnieszka M. Adamczewska, Stephen Morris, 2001. Ecology and Behavior of Gecarcoidea natalis, the Christmas Island Red Crab, during the Annual Breeding Migration. Biological Bulletin, 200(3): 305-320
  5. “Christmas Island: kingdom of the crab,” by Nick Squires., 21 Oct 2007. URL: xxx (accessed on 6 Apr 2010).