The Maldives is a tourist hot spot for dolphin cruises. These majestic animals are found commonly around Gili Lankanfushi and never disappoint with their impressive aerial displays and playful attitude.
The Maldives is a dream destination for wildlife seekers and ocean adventurers. The ocean temperature averages between 27 – 31°C, contains plentiful fish and has incredible visibility. This makes it an ideal location for cetaceans: whales, dolphins and porpoises. They are aptly named as the word cetacean means huge fish.
The Maldives is home to 23 out of the 85 cetaceans species globally. The most common encounters are spinner and bottlenose dolphins. The cetacean species here are very diverse; they range in size from one metre with a weight of 50kg to 30 metres and weighing over 150,000kg. The distribution of coastal dolphins is thought to rely on a number of factors including temperature, prey concentration, location, salinity, depth, tides, habitat type, type of ocean bottom and predation pressure.
The closest living relatives to cetaceans are hippos and other hooved animals like camels and pigs. They diverged from this group over 50 million years ago. The ancestor that made the leap from land to ocean is Ambulocetus which translates to running whale for it could both walk on land and swim, although it wasn’t great at either. This mammal lived in Pakistan and was around three metres in length. Its home was the brackish waters that reside in mangrove ecosystems. Over many millions of years Ambulocetus evolved into the cetaceans that we see today. The changes include the streamlining of the body, the hind limbs regressing, a decrease in hair, increases in blubber content, expansion of the hand bones into flippers, the relocation of the nostrils to the back of the head and changes to the snout.
Bottlenose dolphins are a long lived and larger species of dolphin with a length between two to four metres. Females live around 50+ years while males reach their 40’s. On the upper body they are grey in colouration whilst the underside is paler with the belly being white. Stripes can be observed from their eyes to the blow hole, older dolphins can exhibit spotting on the underside. These dolphins live in a variety of habitats including the ocean, tidal creeks, rivers, lagoons and estuaries. Bottlenose dolphins are one of the most extensively studied species of dolphins as they inhabit inshore environments making them more accessible.
The main calving period for bottlenose dolphins is late spring/summer when the water temperature is at its peak, although they can give birth year round. These dolphins have a yearlong gestation period with an interval of three years between each birth. After birth the calves remain with their mothers for three – four years, this duration is dependent on nutrition and size. These years together are critical for development of social, foraging and courtship skills. These skills can vary greatly between habitats. Weaning of calves starts after three years and within 10 months of the mother’s next pregnancy. The age at which dolphins reach sexual maturity ranges considerably. Females are considered mature between four and 13 years and males at seven to 16 years, the difference in age is dependent on geographical and environmental differences.
Different species of bottlenose dolphins travel in different pod sizes, for example one species prefers travelling in pods between five – ten individuals whilst others in pods between 25 – 100. This variability depends upon food availability, activity, time of day and number of calves. Within these dynamic groups there may be an affinity between a few of the dolphins. These associations are hierarchical and depend on individual range and habitat type. These affinities usually occur between same sexes and mothers and calves. They have been known to last many years, with one association lasting 13 years. It has been observed that females have stronger associations and a larger social network than males.
When hunting bottlenose dolphins use the entire water column and feed on a variety of prey including fish, cephalopods, eels, small rays and sharks. Foraging methods depend on habitat, number of individuals and prey type. Dolphins are known to feed individually, in small groups and can use cooperative feeding strategies including circling, herding and bubble blowing. Dolphins are intelligent hunters, for example some have learnt to follow trawlers whilst others have been observed to use sponges on their nose for protection during hunting. These dolphins can make seasonal movements in response to prey location, water temperature and predation threats.
Bottlenose dolphins share their habitat with other dolphins including spinner dolphins. It is thought that the different species are able to live together due to differences in prey requirements and social behaviours. This co-existence is seen more commonly in the tropics and around coastal islands. This could be due to the higher concentration of nutrients compared to the open ocean.
PADI’s guest blogger Emma Bell introduces herself:
I am a marine biologist and scuba diver from England. I have had the privilege of working in Greece, Seychelles and Maldives. I have worked in an aquaculture research centre where I focused on hormonal manipulation of a pelagic fish species. In addition, I have experience with coral restoration projects including frames and ropes; habitat restoration – crown of thorns, drupella and invasive plant species removal; educational activities and social media updates including blogs. I have also monitored population dynamics of bird, turtle, shark and cetacean species to aid in their conservation. I started my career working in the Maldives and I have done a round trip via Greece, England and Seychelles, I hope to increase my skills set and knowledge further whilst I am at Gili Lankanfushi, Maldives.