MARINE BIODIVERSITY
A frigate bird flies off with a fish it has robbed from a common tern.
The term biodiversity, short for biological diversity, generally refers to the variety of living organisms and the habitats in which they live. The simplest way of quantifying biodiversity is to count the number of species. However, species diversity is not just about numbers. Also important is the range of evolutionary and ecological adaptations species display in the environments in which they live.
Of the 33 main groups of animals, 28 have representatives in marine systems and 13 are entirely marine. Malaysian seas are home to many of these major groups. Species diversity increases towards the tropics in almost all groups of animals. The reasons for this include the length of time the species have existed in tropical regions, the more stable climate over geological time, warmer temperatures, and the greater amount of sunlight which allows high levels of photosynthesis in phytoplankton and other plants—thus building up large food reserves at the bottom of the food chain.
Of the tropical seas throughout the world, those of the Indo-West Pacific region, where Malaysia's seas are situated, are the most diverse. An indication of this is that of the world's 20,000 fish species 4,000 are found in Malaysian seas compared with only 500 in the Bahamas, in the tropical Atlantic region. This high species diversity in the Malaysian seas is even more marked in marine reptiles. Of the 50 species of sea snakes worldwide, 22 are found in Malaysia, and 4 out of the 7 sea turtles species nest on Malaysia's shores.
The seas and coastlines of Malaysia support many different ecosystems, each with its unique range of species, contributing to the country's overall high levels of biodiversity. There are the numerous worms and molluscs on the mud flats, uniquely adapted tree species in the mangrove-lined estuaries, and a myriad of coral and fish species in the coral reefs. The communities of the coral reefs exhibit the highest concentrations of biodiversity. The glorious technicolour hard and soft coral species range from branching staghorn and ridged brain coral to shimmering sea fans and whips, moving with the currents. A vast and varied range of fish live in this designer habitat, their colours and patterns complementing those of the coral.
Many organisms have adapted to survive in specific environments. Marine organisms of the intertidal zone are good illustrations of this fact. The creatures of these areas have devised ways of surviving both in and out of the water. Barnacles keep themselves hydrated—enclosed within waterproof plates—when the tide goes out, and ghost and fiddler crabs have tufts of abdominal hair to absorb the water from damp sand. Yet other organisms have adapted to living in the darker depths of the sea—red seaweeds, for example, have pigments that allow them to make use of the blue light that penetrates to these depths.
Included in the roll-call of marine creatures are mammals such as Fraser's dolphin and the oceanic and shore sea birds which thrive off the rich pickings of Malaysia's productive seas.