Coral reefs are among the most diverse natural system on Earth and corals are the most important piece of this great mosaic. As we know, they are animals able to create a complex structure which provide food and protection to thousands of other organisms such as fish, mollusks, seastars, and so on. Despite being so simple (actually not so simple as we believe), corals are animals like us, although we are much more complex than corals, we do share many similarities in terms of requiring oxygen for to breathing, food for energy our systems can fail and we get sick.
It is not an uncommon sight when we come across corals that seem to be in distress due to particular diseases or bacteria. A disease can be classified as any deficiency of vital body functions, systems or organs and is a natural aspect of coral populations and also one mechanism in which coral populations are kept place. Coral diseases can be caused by bacteria, viruses or fungi and may cause significant changes in the community structure, species diversity, reproduction and growth rates as well as the abundance of reef-associated organisms. There are several mechanisms and environmental conditions that support disease transmissions such as high coral cover, water quality and certain predators (corallivorous fish, polycheates and gastropods).
Similar to human populations, certain coral colonies with high abundances are also more susceptible to diseases and this is because some diseases spread more rapidly within crowded populations for example the white band disease, a highly contagious disease that affect any healthy coral tissue through direct contact. The band, which ranges between few millimeters to 10 centimeters can work its way from the base of the coral colony to the branching tips at a rate of approximately 5 millimeters per day. The result is a dead bare skeleton which may later be colonized by filamentous algae. Diseases such as white band disease, white pox, aspergillosis and white plague are believed to be caused by known bacterial pathogens whereas some diseases such as black band disease may be caused by a complex association of microbes and may contain up to 50 different bacterial types within the disease.
Another disease which has also been identified on one of the coral frames is skeleton-eroding band disease (SEB) which is a visible as a black or dark grey band that slowly advances over corals, leaving a spotted region in its wake. SEB was first noticed 1988 near Papua New Guinea and then in Great Barrier Reef and also Mauritius in 1990. It was only in 1994 when surveys around the Red Sea regarded this condition as a unique disease and is now considered of the commonest disease of corals in the Indian and Pacific Oceans, especially in warmer more polluted waters. SEB is a progressive disease and they can spread over an infected coral at around 2 millimeters per day in colonies of Acropora.
Many coral diseases have not been thoroughly characterized and the causative agents for many diseases still remain unclear. Understanding the causes and impacts of coral diseases allow managers and conservationists to understand how coral reef management and human impacts affect the spread and severity of these diseases and make informed management decisions. Here at Thudufushi we do our best to inform all visiting guest about the importance of corals and how to behave when in the water during excursions. Our coral conservation project also aim at restoring damaged coral fragments by attaching them onto steel structures which would, given the right conditions, grow into a small coral reef. As unfortunate as it is to see corals fighting against these diseases, there is not much we can do for them in nature. As for the coral frames, we do our best to remove any infected corals before they spread to the healthy corals
Further reading and video:
Have you ever noticed how fish color differs between species? Reef fishes are aware of their colors and they use this to their advantage in their surroundings by means of camouflage and protection against predators. At the same time, their colors can also be used for thermoregulation, communication between species or attraction of mating partners.
Various patterns such as horizontal and vertical stripes, unusual spots, “false-eye” patches and other shapes have evolved for decoration and concealment and play an important evolutionary role in their development. In addition, color patterns may also change during the development of certain fish mainly due to physiological changes during their lifecycle. An example is the Oriental Sweetlips (Plectorhinchus vittatus). During its juvenile phase it has an attractive brown-and-white and yellow mottled pattern whereas the adult can easily be recognized with its yellow and black horizontal stripes. Numerous other species of triggerfish, angelfish, parrotfish and wrasses also have these color morphs from juvenile to adult and it is assumed that these patterns or colors of the juveniles may be less visible to predators.
A number of reef fishes also have different colors according to whether they are male or female and in a community where sex change is the norm, this is an important manner of attracting a mate. Males tend to be more brightly colorful as is the case with many parrotfishes and wrasses and is very useful for attracting mates or to intimidate others. In the case of parrotfish, its been found that all females appear to change sex which is also accompanied by a change in color should they live long enough. Wrasses are also known for their drastic color changes accompanied by sex change.
Color patterns can also serve as a warning. Have you noticed how animals on land may all use the same tactic? Animals such as frogs, snakes or insects use vivid red, yellow or orange colors to signal that they are venomous, and predators would do well to stay clear of them. On the reef, plenty of fish use their striking patterns and bold colors as a warning. Examples of toxic or venomous fish include most pufferfish species with their distinguished bright colors and characteristic patterns or the venomous lionfish which are well known for their red, white or black bands with venomous spines and unique tentacles.
Attempts at understanding the unique range of colors of reef fishes and whether they have a biological significance have been long debated. There can be overlap amongst different functions and meanings of their color such as mimicry and color sexual trait. Their colorful appearance lies in the fact that fish see colors differently than humans and their position on the reef is likely affected by the absorption of light and the wavelength of colors. None the less, the debate about diverse fish colors and patterns and how they are changing remains a complex topic and requires much more research
The Maldives rank among the top five places worldwide for watching whales and dolphins. Over 20 different species of marine mammals call the Maldives their home.
While cruising in the oceanic water surrounding the Maldivian atolls you may enjoy the encounter with the mighty Blue Whale (Balaenoptera musculus), the highly acrobatic Spinner Dolphin (Stenella longirostris), the Sperm Whales (Physeter macrocephalus) or the powerful Orcas (Orcinus orca).
Such great abundance of cetaceans is due to the nutrient rich water which supports the feeding habits of cetaceans. In addition, the ban of any hunting activities by the Maldivian law and the establishment of the Indian Ocean Whale Sanctuary in 1979 has fostered cetacean populations.
Most of the cetaceans inhabit the deep waters of the open ocean near the atoll boundaries while others are more abundant in the shallower waters of the atolls. Actually, nearby Athuruga and Thudufushi it is not rare to see cetaceans, including pilot whales (Globicephala spp.), mostly during January to March, bottlenose dolphins (Tursiops spp.) even if less common, and the spinner dolphins (Stenella longirostris) probably the most common sighting.
“Dolphin Check” is the typical tour focusing on searching for pods of dolphins to enjoy a magical encounter. Along the excursion, the marine biologist will include a detailed talk on board to unlock the mystery around the life of dolphins. The searching step is not random at all, we all know where to look for them! This is due to the fact that spinner dolphins follow a distinct daily pattern. They travel to shallow and protected lagoons during the day, to rest and socialize, while they travel outside the atolls using specific channels (called “Kandu” in Dhivehi, the local language) in order to get ready for the night hunt. They primarily feed on small fish and squids surfacing from the oceanic deep water during the night. It is also common to see a pod of dolphins swimming close to the Thudufushi house reef while having breakfast at the restaurant or the terrace of your watervilla.
Once the dolphins are spotted, we usually shout “koamas” which means dolphins in Dhivehi, and the captain will turn the boat towards the pod. At this moment the approach is slow and not directly towards the dolphins, they choose if they want to play with us or not. Usually, they start to swim in front of the bow of the boat. Spinner dolphins are particularly famous for their bow-riding preference Bow-riding is when dolphins position themselves in such a manner that they are lifted up and pushed forward by the circulating water generated by the bow pressure wave of an advancing vessel. It is not really known why dolphins bow ride. At times they may appear to bow ride to get from one area to another while saving energy. Bow riding is even something dolphins appear to enjoy doing and often do for fun, just like when people go body surfing.
Sometimes, instead of bow-riding we can enjoy different behaviour, for example, they may start performing acrobatic jumps, from which their name comes from. Skilled acrobats, the small dolphins regularly leap out of the water and perform complicated aerial manoeuvres. They can spin multiple times in one leap, which can be nearly 3 meters high.
The power of the spin comes from the tremendous acceleration under the water and the torque of the tail just as the dolphin breaks the surface. Dolphins may also make nose-outs, tail slaps, flips, head slaps and side and back slaps. The leaping and spinning likely serves several purposes, including the removal of irksome remoras. They also use their moves to communicate, each one signalling something different: “Let’s go” or “Danger!” or “I find you attractive”.
Despite our efforts in understanding and protecting these magnificent spinner dolphins and all the marine cetaceans, there are several threats to their survival. A big threat for spinner dolphins is by-catch. As they frequently swim together with schools of yellow-fin tuna or other commercially targeted fish, they may be trapped and caught in big nets as by-catch. Sadly, it seems that thousands of dolphins die every year because of by-catch.
On the International Union for Conservation of Nature (IUCN) their status is highlight as “Least Concern”, meaning that their population is not under sever threat, however data on global population status is missing, and adequate information is needed to make an assessment of its risk.
Surely, the best practice for protecting dolphins from by-catch is to buy “Dolphin safe” tuna can. In addition, a study, published in 2018 on Science, highlighted the best practice to reduce our impact on the planet and protect marine and land life. By reducing the consumption of meat and fish we can reach a sustainable use of the food resource worldwide.
If you want to know a little more about dolphins:
IUCN website on spinner dolphin global population:
On bow-riding and spinning:
TheGuardian article regarding the study on sustainable products consumption:
Suggestions on easy solutions:
The “Big 5” is a fairly known term for those who have travelled to Africa, particularly Southern Africa. For those less familiar, the Big 5 refers to the most iconic and charismatic animals of the country. It is these animals that we have a particular interest in seeing and also those that we applaud in terms of conservation. Maybe you have different reasons for visiting the Maldives, but at some point, the blue waters are calling to each of us to explore the natural beauty within. Flying over multiple atoll islands with the seaplane towards your destination you can clearly see the outlines of the coral reefs around and often times, depending on your location and height you can even spot some mantas, dolphins or whale sharks. This brings me to the topic of this month’s blog: the Big 5 of Maldives. An estimated 2000 species of marine life can be found in the Maldives and many of which can be found living amongst the coral reefs. Not all these species have a direct association with the reefs, but many of them rely on these areas for shelter, food or cleaning at some point. The four other species discussed here is marine turtles, dolphins, mantas and sharks.
You may not be aware, but corals are actually tiny invertebrate animals called Cnidaria. These animals (includes jelly fish and sea anemones) all share the same distinguishing characteristics, a simple stomach and a mouth opening covered with stinging tentacles. Each individual animal is called a polyp and they live in large colonies which creates coral reefs. These animals have been around for nearly 500 million years and even outlasted the dinosaurs. Today they cover a mere 1% of all our oceans and 3% of the world’s corals can be found right here in the Maldives, 9% in the Philippines and another 15% in the Great Barrier Reef. In 2016, a worldwide El Nino event (heating of the ocean waters) killed more than 60% of the corals in the Maldives and around the world more losses were reported with some reefs completely disappearing. Luckily the reefs are slowly starting to recover and their colors are returning once more.
Marine turtles have been around for almost 100 million years and they are of the only reptiles that inhabit marine environments except for marine iguanas and sea snakes. Worldwide there are around 7 species of turtles and 5 of them can be found here in the Maldives. You can read more about these amazing animals in our previous blog.
Dolphins are part of the group called Cetaceans which also includes whales and porpoises. There are over 81 species of cetaceans in the world and can be found in varying parts of our oceans. Furthermore there are those such as the killer whale, pygmy killer whale, pilot whale and melon-headed whale which is referred to as “whales”, but are in fact dolphins. They are highly intellectual and social animals and can often times be spotted in big pods hunting, feeding and even playing together. In the Maldives there are roughly 20 species of dolphins and the most common one is the spinner dolphin. You can read more about this species and dolphins in general in our newest blog post.
The last two species of the “Big 5” is manta rays and sharks. These species, unlike the bony fish are classified as cartilaginous, meaning their skeleton is made of cartilage, a bone similar to what humans have in their ears and nose. This makes them lighter and more flexible in their swimming capabilities. Similar to stingrays, they are classified as elasmobranchs, meaning plated gills. Compared to other fish species with their gills covered inside the operculum, mantas, stingrays and sharks have “open” gill slits below the body (i.e. mantas or stingrays) or on the side of the body (i.e. sharks) which they use for extracting oxygen from the water. Manta rays can be found in most tropical waters around the globe and two species can be distinguished, the giant oceanic manta (Manta birostris and the reef manta (Manta alfredi), the former being the most commonly sighted in the Maldives. These animals have a unique spot pattern on their ventral side which is similar to a human fingerprint and can be used by scientists to tract their movement and population with the use of photography.
Lastly, sharks. The first shark fossil ever discovered dates back to around 370 million years and looking at their shape, they haven’t changed much over the course of evolution, which means they doing something right. Today there are over 500 species of sharks, although with developing technology this number constantly changes as they discover new parts of the ocean. In the Maldives there are over 26 species of sharks in various parts of the atolls and the biggest one of all is the whale shark. Not only is this the largest shark, it is also the largest fish in our oceans, measuring up to 18 meters and weighing up to 20 tons. Like the manta rays, they are also filter feeders, meaning they feed only on the tiny particles living suspended in the water, more commonly known as plankton. They will spend hours of traveling searching for sufficient “blooms” where they will gorge themselves up to 30,000 calories worth of food. These really are the gentle giants of the ocean and are magnificent to behold.
If you want to read more about these animals, you can follow these following links
Turtles: https://coralframe.planhotel.com/2019/03/22/get-know-marine-reptiles/ & http://wwf.panda.org/knowledge_hub/endangered_species/marine_turtles/
Dolphins and porpoises: https://www.worldwildlife.org/species/dolphins-and-porpoises#
Manta Rays: https://www.mantaray-world.com/ & https://www.fisheries.noaa.gov/species/giant-manta-ray
Sharks: https://www.worldwildlife.org/species/shark & https://defenders.org/sharks/basic-facts
This month is the dawn of a new beginning for coral reef rehabilitation at Thudufushi Diamonds Resort. Our latest frame number 94 is now the start of our new cutting-edge project that pertains to coral reef rehabilitation. Our mission remains the same, to provide the much needed stability for naturally or unnaturally broken fragments in an act to return a degraded ecosystem back to its predisturbance state. In our new project we are using new and innovative designed structures that are inexpensive and more practical on a large scale. These structures also allows for better unrestricted water flow, trapping broken coral fragments and rubble, it effectively stabilize the substratum and as a result support high coral recruitment, growth and diversity. Following the methods and design of a recent large-scale coral reef rehabilitation project in Indonesia, we will be placing these structures in a large degraded area of our reef in order to create a chain that will stretch easily over 150 meters with the aim of stabilizing the damaged section by increasing the live coral cover and restoring it to its once pristine condition.
Their hexagonal shape consist of the same materials as before which is reinforced steel bars (rebars) covered in proxy glue and coral sand, however our new “spiders” are much smaller and lighter compared to the triangle shape used before, which make its construction cheaper. The benefit of the spiders are that they can be placed in much shallower water without being exposed during the low tide, they are more stable on uneven surfaces and they are more effective for large-scale restoration. Results from the study showed that the live coral cover on the structures increased from less than 10% initially to greater than 60% between 2013 and 2015. Although this large-scale study consisted of approximately 11,000 structures covering up to 7,000 m2 our smaller project is only the beginning and if successful we will implement these structures over greater areas of the reef.
Images in the slideshow below show the new design of the spiders, our first frame of the project as well as the location for the first chain in the lagoon.
and for the technical report
Along with Manta Rays and Whale Sharks, Sea Turtles are of the most wanted encounters in the Maldives. Everyone wants encounter a graceful moving sea turtle, see their hatchlings coming up from the sand or even touch the sea for the very first time.
So, get ready for some advice and facts about these wise reptiles!
Globally, there are 7 species of sea turtles in the world: Green, Hawksbill, Loggerhead, Olive Ridley, Leatherback, Kemp Ridley and Flatback. In the Maldives it is possible to encounter at least 5 of these species (first 5 listed before).
One of the most common species of sea turtle you can spot on our coral reef is the Hawksbill turtle (Eretmochelis imbricata), a smaller species of (up to 1 meter) and also the magnificent Green turtle (Chelonia mydas). The former Hawksbill turtle are considered as one of the most endangered species of sea turtle in the world and also listed as Critically Endangered by the IUCN (The International Union for Conservation of Nature), meaning they face an extremely high risk of extinction in the wild in the next few years.
Green Turtles, so called due to the green colour of the fat under its shell are currently listed as Threatened, not far behind the former species, they may also soon be in danger of extinction. Green turtles feed mostly on sea grass and algae, and they are the only sea turtle that is strictly herbivorous as an adult. You can easily see them tearing vegetation between different patches of corals or swimming around seagrass meadow in the shallow lagoon.
Since 2015, Thudufushi hosted 3 sea turtle’s nests. Building a nest is long and hard work: the female can spend anything between 4 to 6 hours to find a suitable area of sand, where she then digs a circular hole 40 to 50 cm in depth and lays on average 150 tiny ping-pong sized eggs. She then camouflages the nest with sand using her rear flippers and returns her journey back to the ocean, leaving the eggs untended. After around 60 days, hatchlings break out of their eggs and out of the sandpit. This usually happens during the night to order to avoid predators where they use the moonlight and calibrate their internal magnetic compass to reach the sea. Once in the water, turtles swim between foraging areas and migratory routes until they reach maturity. Much of this time is know as the “lost years”, since there is little information about turtles during this period. Due to the low survival rate, it is estimated that only 1% of hatched sea turtles will survive to reproductive maturity.
Sadly these species of turtles are prized for their beautiful shells (carapace) their scutes, streaked with amber, black and brown nuances, are still used to make hair ornaments, jewellery and other decorative items in some countries. Meat and eggs are used for human consumption. Many countries believe the eggs have aphrodisiac qualities, but there is no scientific evidence to support this.
Other indirect threats for sea turtles include bycatch and ghost nets; this is commercial fishing nets that have been lost, abandoned or discarded at sea, but, in the water, they can trap almost anything that swims around. Along with these, marine debris is of the most significant problems in our oceans, not only to turtles, but also all marine life worldwide, because of ingestion and entanglement. More than 80% of this plastic is derived from land. It washes out from landfills, beaches and the streets. It travels by winds and storm drains that lead into rivers, streams and our oceans. As a result, thousands of turtles accidentally swallow these plastics, mistaking them for their food. This plastic can fill the stomach of the turtle, thus making less space for nutritious food and as a result cause the turtle to starve. Plastic and other marine debris can also block the movement of food within the gastrointestinal tract which can have severe health implications. An ingested plastic bag can also cause a turtle to dive incorrectly. Basic movements such as swimming and diving will require lot more energy which could be invested in finding its food.
With so many things threatening sea turtles, we need to help them with their survival!
You must remember that we share our oceans and beaches with many other species and many have been there before we started to harm their habitats. Respect the environment and think how every one of our actions can have a possible effect on other organisms, is a must!
You can help by doing regular clean-ups, use less plastic in your household, avoid using straws and contribute to conservation projects who aim to conserve the protection of sea turtles.
You will be surprise about how many things we can do all together.
For further information:
About rescue and research on sea turtles in the Maldives
On marine debris and sea turtles interaction:
About sea turtles and plastic straws:
Bioluminescence is the creation of light by a living organism through a biochemical reaction.
In other words, some creatures are able to create their own light, just like we turn on the light in a room by pressing a switch.
The chemical reaction involves oxygen, an enzyme called Luciferase and a chemical named Luciferin.
The result is a cold light, with blue, light blue, green and sometimes purple colors.
Since light is one of the most important variables in the marine environment a variety of different organisms, from bacteria to fish, have developed the ability to produce light.
This light is used for communication, defense or hunting, where light is absent, for example during the night or in the very deep ocean.
In fact, sun light starts to decrease with depth. In tropical areas, once we reach 150-200 meters and below in depth, the dominant light in not sun light, but bioluminescence!
In the deep and dark ocean, bioluminescence is vital for a great variety of organisms.
The firefly squid, known as Watasenia scintillans, occurs in the Western Pacific Ocean at around 300 meter depth. It owes its name to the presence of tiny photophores through the entire body which may be flashed to attract small fish for a meal or a partner for a blind date. Furthermore, it produces light for counter-illumination camouflage: it matches the brightness and color of its ventral surface to the light coming from the surface, making it difficult for predators to detect it.
However, bioluminescence also occurs in very shallow water, for example the famous phenomenon known as “Sea of Stars”. In the Maldives, you can be lucky enough to see bioluminescence in action right on the surface of the sea, or walking on the wet sand of the beach at night. What is really happening is that so called Dinoflagellates, which are tiny unicellular algae, are stressed by the movement of the water or sand caused by our body. As a response they produce bioluminescence in order to scare you or the potential predator with this sudden and unexpected light.
There is not best season for spotting bioluminescence, so you will need a little bit of luck to see this natural firework in the water. In any case, it is a great bonus after your sunset snorkeling or during a night walk.
For further information, an interesting talk about bioluminescence with amazing videos:
For more scientific information about mechanisms, diversity, and ecology of bioluminescence in dinoflagellates:
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
and for more technical information about the migration of mantas in the Maldives, visit this link
It is almost impossible to believe that the coral framework of the Maldivian ecosystem which existed for nearly 57 Million years is now under threat. Threats to the oceans such as plastic pollution, overfishing and mass occurrence of coral eating predators are now the leading headline of many articles in newspapers and scientific reviews. We cannot deny hearing about the phenomenon called “coral bleaching”, which may be confusing for the average reader, but is a recurring threat for any marine biologist.
Coral bleaching is often mistaken for a chemical reaction in corals simply because of the false connection between “bleach” and “chlorine”. In fact, coral bleaching is a recurring occurrence that happens when ocean surface temperatures heat up for longer than usual periods of time. The coral animal that lives in a mutual relationship with the algae called zooxanthellae that provide it with food and oxygen may expel itself from the polyps (in which it is housed) when stress levels becomes too high (such as in El Niño years). Once this tiny algae is no longer present, the transparent tissue of the coral skeleton become a bleaching white color. Corals that are bleached totally white, having lost nearly all of their symbiotic algae, have an extremely low chance of recovering because it takes several months for the algae to come back. In contrast, most corals that are only partially bleached will survive and recover quickly.
So how can we restore what has already been lost? The coral adoption and restoration initiative has great ecological value as it involves replanting reef fragments to accelerate the regeneration of coral growth in the Maldives’ reef-fringed atolls. Various methods are adopted in the Maldives and its success is monitored over many months and years. The contribution to coral reef conservation may include attaching coral fragments to steel structures, ropes attached to frames (floating nursery), to monofilament hanging from tree-shaped structures and sometimes mesh nets floating in mid-water of the reef.
The initial aim of attaching a coral to an artificial structure is to take it out of the sand and rubble where it could get smothered and subsequently, as it grows, it can adapt to its new surrounding conditions and grow to a juvenile size before it can get used to restock damaged reefs. Once it reaches sexual maturity it will be the base of a new breeding stock that can colonize even distant reef areas.
This necklace of atolls that make up the island of the Maldives are characterized by beautiful blue oceans and amazing white sandy beaches and is situated in the Indian Ocean to the south of India and west of Sri Lanka. From north to south the chain of atolls extends a mere 648 kilometers and consists of a total of 1,200 islands, approximately 100 of these are holiday resorts and another 200 which are inhabited. Although considered as uninhabited, some of the other islands are used for crop cultivation and various activities that also include tourism. Today, the Maldives are known for their fragility in the face of global warming, where the rising sea levels could cause these low profile islands to completely disappear (The highest point in the Maldives lies in the Addu Atoll at 2.4 meters!). The tiny islands we see today are the remains of volcanoes that belongs to the Chagos-Maldives-Laccadive Ridge which, over millenia, have subsided leaving behind the coral-fringed flattened tops as the only evidence above water that they exist.
In its surrounding waters, over 2000 species of fish can be found that ranges from the tiny, colorful reef fish, moray eels and rays, to giant pelagic fish, such as tuna, sharks, dolphins and whale sharks. The Maldives is home to five of the world’s seven species of sea turtles, two of which are regularly seen, namely the critically endangered hawksbill turtle (Eretmochelys imbricata), and the endangered green turtle (Chelonia mydas). The islands provide critical nesting sites for the green turtle and many conservation programs are focusing on protecting these sites and the tiny hatchlings that emerge from them. Due to the small size of the island nation, there are very few land-based mammals, amphibians, and reptiles, most of which are widely distributed throughout the atolls. There two species of fruit bat, as well as Maldivian garden shrews. Cats, rats, and mice have been introduced by humans, often invading the uninhabited areas of islands and becoming pests, and it is strictly forbidden to bring domestic dogs to the Maldives.
Due to the oceanic location, the avifauna of the Maldives consists mainly of pelagic or seabirds. There are over 100 species of birds around the islands, 36 of which are seabirds, such as the seasonal frigate birds, and white terns. Other bird species that inhabit the marshes and island bushes include the grey heron, various species of plovers, sandpipers and gulls, as well as swifts, doves, pigeons, sparrows, swallows, and shrikes. The national bird of the Maldives is the white-breasted waterhen (Amaurornis phoenicurus).
Vegetation and other ecological features vary between islands from the north and south of Maldives, moreover these features also vary between interior and exterior islands. Since the exterior island is subjected to greater oceanic currents, vegetation is continuously subjected to harsh environmental factors and the profuse growth of trees, some of which may attain even 30 m height, indicates the uniqueness of the Island’s terrestrial vegetation. Tall trees such as Ficus, Casuarina and Coconut are very common in most of the islands. Large mangrove trees are characteristic of some of the northern islands. In general, the diversity of terrestrial flora is low because of the uniform topography, soil and climate. However, the islands support extremely rich coastal vegetation.