The word plankton derives from the Greek word for “wanderer” or “drifters” and it is applied to a variety of organisms that, essentially, are weakly swimmers. These organisms inhabit all oceans, rivers and lakes from tropical regions to the Arctic and Antarctic. Furthermore, they represent the baseline of the marine food chain and one of the most important suppliers of oxygen.
In fact, a particular group called “Phytoplankton” is considered the main life-support system on Earth. While you are reading this article, you are probably breathing part of this oxygen, since these marine plants produce around 50% of the global atmospheric oxygen.
Phytoplankton esentially comprises of unicellular and multicellular algae. Along this group the zooplankton is the “animal” part encompassing small crustaceans, various larvae, jellyfish, combs and many others. So, generally speaking, plankton is not necessary linked to “size” since we may have bacteria of few micrometer (Nanoplankton) to jellyfish longer than 30 meters (Megaplankton)!
Zooplankton is also the favourite food of a great variety of gigantic inhabitants of the oceans. Whales, mantas and whale sharks are the frequent visitors of areas where zooplankton is abundant. Such “restaurants” are distributed in various parts in the world and are linked to seasonality. Thus, depending on where these special restaurants open whales, mantas and whale sharks migrate or move, sometimes for thousands of kilometres across the oceans.
In the Maldives, we may experience directly and easily observe the yearly migration of mantas. The distribution of these gentle animals is strongly influenced by the seasonal reversing of the monsoons. Wind blows from South-West during May to October and from North-East during December to March. As wind direction changes also oceanic currents change, thus nutrient rich water is abundant down-stream. Here, phytoplankton abundance may increase (an event called “bloom”), followed by zooplankton and eventually, mantas!
To answer the question “When is the best period to see mantas?” we need to follow the plankton blooms: from May to October on the East side of the atolls and from December to March on the West side of the atolls. In this way you can enjoy amazing snorkelling and diving excursions with mantas!
The plankton world is complex and surprising, nevertheless, we need to remember an important fact: a world without plankton is a world deprived of life, where also human-beings are excluded. Thus, we need to take care of our blue life support system as we take care of our own lives.
For further information visit these links
https://www.nationalgeographic.org/activity/save-the-plankton-breathe-freely/
and for more technical information about the migration of mantas in the Maldives, visit this link
