Whether donning a regulator and scuba tank or just a mask and flippers, the best way to appreciate Malaysia’s underwater marvels is to get wet and have a look for yourself. Take a dip beneath the waves with Jennifer Cantlay as she experiences the wonders of Malaysia’s superlative underwater kingdom.
The tropical seas around Malaysia’s 4,675-km coastline harbour a variety of important marine habitats that support a huge number of species. Coral reefs are the most colourful and complex of these ecosystems, often described as “the rainforests of the sea” for the diversity of life within them, yet overall they cover less than one-tenth of one percent of the ocean floor worldwide.
Fantastic coral reefs can be found in abundance off the coast of East Malaysia, making Sabah one of the world’s top diving destinations. There are over 25 islands in the Celebes Sea, Eastern Sabah, which include the famous dive sites off Sipadan and Mabul islands. Divers are fortunate to find over 550 different types of coral in these tropical waters, which fall within the “Coral Triangle,” a six millionsquare km marine area containing over 75% of all known coral species worldwide. The area includes the seas around East Malaysia, Indonesia, the Philippines, Papua New Guinea, Timor Leste, and the Solomon Islands and is recognised by scientists to contain the highest biodiversity of marine life in the world. The Coral Triangle shelters at least 2,200 different species of reef fishes, providing them with safe spawning sites, nurseries for juvenile fish, and feeding grounds. Whales, dolphins, and dugongs all feed, breed, and follow migratory routes in this region. Six of the world’s seven species of marine turtle inhabit the seas within the Coral Triangle, with several major hawksbill and green turtle nesting sites found in Malaysia. Consequently, this country provides an underwater paradise for diving and snorkelling enthusiasts.
Many of us have been fortunate to swim in these tropical waters and experience the vibrantly colourful explosion of life in the coral reefs. However, we may not have appreciated the fact that the dazzling variety of corals forming the reef exists entirely because of the fascinating symbiotic relationship between coral animals and photosynthetic algae, called zooxanthellae. Corals exist in a special partnership whereby their polyps (each an individual miniature coral individual only millimetres in size) receive organic nutrients and oxygen for growth from the zooxanthellae that live inside their tissues. In return, the algae are provided with a safe home and a constant supply of nutrients (phosphate, nitrate, carbon dioxide) from the coral polyps. The coral colonies then have enough energy to produce the protective calcium carbonate skeletons essential for building the reef itself. It is vital that coral reefs receive sufficient sunlight for the algae to flourish and so they are naturally (and happily, for humans) limited to growing in shallow seas, which allow us to easily enter into their realms. It would be impossible to describe all the marine species that you may encounter here, so here is simply a brief introduction to some of the more distinctive and unique characters on the reef.
Predators and Prey
Some of the top predators roaming around are sharks, which are often feared and misunderstood by people. Many common shark species, such as blacktip and whitetip reef sharks, are not aggressive to humans and are simply curious to meet us in their own territory. During the day, they rest in favourite spots under ledges, hidden in caves or lie motionless on the seabed and often ignore fish (and divers!) swimming by. This docile behaviour changes at night, when they become stealthy and speedy hunters relying upon surprise tactics to catch fish unawares. Sharks have evolved over the course of 400 million years to locate prey with highly developed visual, tactile, olfactory, auditory, pressure, and electro senses. Their most unusual skill is the ability to detect fish from the electrical fields they emit by using electro-sensors on their head, thus providing accurate target location at close range. We may gain some insight into their lives during night dives when their skilful hunting techniques can be observed firsthand.
Another nocturnal predator is the moray eel, which prowls the reef using its acute sense of smell to find a meal of fish or crustaceans. The eels prefer to rest their long, slender bodies in crevices during the daytime and so divers may notice just the head poking out from the coral. The rhythmical opening and closing of the eel’s mouth may seem alarming to divers, but this behaviour simply allows water to continually flow through the gills for breathing. Despite having sharp fangs, moray eels are unlikely to bite a person unless they feel threatened.These charismatic creatures are often well hidden on the reef as they use a variety of pattern and colour combinations to provide camouflage. Therefore, it is a real privilege to be able to see one in its natural environment.
Groupers are one of the largest predatory fish species on the reef, with some individuals weighing up to 180kg and measuring over two metres in length. The 20- to 40-year lifespan of certain grouper species helps them to reach this prodigious size. Despite their stout appearance, groupers can pounce upon more agile fish with surprising speed from a motionless position. The grouper’s strong jaws and rapid mouth opening allow them to exert significant forces to pull fish from hiding places and suck them in. In spite of their size, groupers may become prey for bigger predators, such as sharks, and have therefore developed a technique for intimidating other hunters by vibrating their swim bladder to produce loud booming sounds. However, divers are more likely to become aware of a grouper on the reef from seeing its great size rather than from hearing its defensive sounds.
Lizardfish are also common ambush predators but are significantly smaller than groupers, only reaching up to about 60cm. The name is due to the lizard-like appearance of the head, making them readily identifiable underwater. The mouth is filled with sharp teeth attached to both the jaws and the tongue, which help prevent the accidental release of struggling prey. These fish are often surprisingly tolerant to a slow and close approach by humans, but will then suddenly dart away rather than bite.
Survival of the Fittest
Many reef fish have weird and wonderful reproductive strategies designed to increase their chances of breeding success. Highlighting grouper fish once again, it known that they are hermaphroditic, having the ability to become females or males. They begin life as females with the capacity to become males as the need arises. If the male grouper is removed from guarding his harem of females, then reproduction is temporarily halted until another female changes into a male to take over the mating role. This sex changing ability can also occur in hawkfish, whereby they initially reach sexual maturity as females but some can later change into males to gather up chosen females into harems, thus reducing the difficulty of finding a mate. Similarly, the anemone fish can use its sex-changing skills in certain situations to benefit the population. This occurs upon the death of the most dominant female anemone fish that was paired to the next-ranking male anemone fish. This event causes the male partner to change sex and become the new dominant female and then attract a new subordinate male to form the next breeding pair. In contrast to sex changes for mating purposes, cardinalfish maximise the chance of successful egg development by an unusual incubation technique. After spawning, the male cardinalfish incubates and protects the fertilized eggs in his flexible mouth and so is unable to eat food during this time. This personal sacrifice enables an effective incubation period to produce the next generation of cardinalfish.
There are also many unusual invertebrate animals to be found here, ranging from gracefully gliding flatworms to stinging sea anemones. Perhaps the most bizarre in appearance are the nudibranchs, which are essentially underwater snails without shells and have special tufted gills along their backs for breathing. Their vibrant and garish colours warn potential predators against attacking them because their toxic secretions and stinging cells make them an unpalatable meal. Some nudibranchs have even evolved to eat each other, with certain cannibal species engulfing and dissolving others using special enzymes, so even their own kind are not safe on the reef from gastropod greed!
Hopefully, this snapshot exploration of creatures in the coral reefs has increased your curiosity and encouraged you to discover more amazing marine life in Malaysian waters for yourself. Living in or visiting this country provides a wonderful opportunity for starting a new aquatic interest, with many great dive sites only a short flight connection away from Kuala Lumpur. For example, the many beautiful islands in the Celebes Sea can easily be reached by flying to Tawau, Sabah, then arranging a road transfer to Semporna, from where you can catch a boat across to Sipidan. At Sipidan, you will soon be diving adjacent to coral walls dropping more than 2,000 metres straight to the seafloor and most likely watching green turtles, barracuda, and manta rays swim by. There are even some marine species yet to be identified by science that live there. So as you can see, once you start diving or snorkelling, you will soon become enthralled by Malaysia’s stunning underwater world.
Source: Senses of Malaysia November/December 2013
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