Marine Mammal Groups of Sri Lanka

Saturday, October 10th, 2020 | Blog

Like all other mammals, including humans, marine mammals give birth to welldeveloped young following a period of internal gestation and nourish them during their early lives by suckling. They also share common mammalian characteristics such as endothermy (producing the warmth they need to function from within their own bodies), air-breathing and well-defined limbs. A few even have fur at some point in their life-cycle – dolphins, for example, are born with a few bristly hairs on their chins. Marine mammals also tend to be highly intelligent; indeed, dolphins are considered to be among the most intelligent animals on Earth.

Marine mammals in the Indian Ocean belong to two distinct groups: cetaceans and sirenians. The former include whales, dolphins and porpoises, while the latter comprises manatees and dugongs. Members of both groups are found in Sri Lankan waters. Other marine mammal groups include pinnipeds (seals, sea lions and walruses), sea otters and the polar bear. None of these are found in the vicinity of Sri Lanka.

Cetaceans: Whales, Dolphins & Porpoises

Cetacean (pronounced ‘see-tay-shun‘) comes from the Greek word ketos, meaning sea monster.

A Latinisation of this word, cetus, is used in scientific terminology to mean’whale’. Cetacea is the name formally given to the order of placental mammals having a blowhole for breathing and no hind limbs. Cetology is the branch of marine science associated with the study of whales, dolphins and porpoises.

Worldwide, zoologists have counted some 90 cetacean species (the actual number varies depending on various taxonomic controversies).

Confirmed sightings of 28 of these have been made in Sri Lankan waters, with a further two whales tentatively identified; in all, 14 species of whale, 15 species of dolphin and one porpoise species are possibly found near or around Sri Lanka at various times of year. It should be noted, however, that taxonomic classification of cetacean species is not perfect, and there are arguments over whether some cetaceans sighted in these waters should be classified as separate species or grouped together as one. Other species may have subspecies associated with them. It is hoped that this book will help resolve some of these controversies by making it possible to identify marine mammal sightings more accurately.

As common names vary by country and even region, the standard scientific names for each species are used in the Observer’s Guide. These names are recognised worldwide and using them helps us accurately identify and describe our sightings for others.

Quoted from Out of the Blue, by Howard Martenstyn