Cetaceans are marine mammals divided into 2 sub-orders : odontocetes, which have teeth, and mysticetes, which have baleen. There are 85 species of cetaceans, of which at least 16 frequent Polynesian waters. A sanctuary for marine mammals was created in 2002 to protect them and a local law governs their approach. It is one of the few places in the world where it is still possible to swim with cetaceans.
Among the mysticetes, the most frequently encountered is a migratory species : the humpback whale (Megaptera novaeangliae). Anecdotally, Bryde’s whale (Balaenoptera edeni) has been sighted. Mysticetes have baleen – long keratin blades implanted on the upper jaw – allowing them to filter their food, made up of small organisms (plankton, krill, small fish). They are quite solitary animals unlike toothed cetaceans.
Among the mysticetes, the most frequently encountered is a migratory species : the humpback whale (Megaptera novaeangliae) Anecdotally, the Bryde’s whale (Balaenoptera edeni) has been seen. Mysticetes have baleen – long keratin blades implanted on the upper jaw – allowing them to filter their food, made up of small organisms (plankton, krill, small fish). They are quite solitary animals unlike toothed cetaceans.
Weight : 30 to 40 tons
Life expectancy : > 60 years
Physiognomy : Large and robust body. Flattened, triangular head with protrusions containing vibrissae. Characteristic pectoral fins up to 5 meters long.
Color : Dark gray to black back. Ventral area generally white, which may be black except for the underside of the pectoral.
Observation area : All oceans
Food : Small fish, krill, plankton
It is an emblematic migratory species of French Polynesia, which has been reconquering Polynesian waters since the 1990s, which it probably liked but from where it disappeared following industrial whaling which almost exterminated the species during from the 19th and 20th century. Thanks to its protected status and the moratorium on commercial hunting established in 1966, the data show that the population of the species has been increasing steadily and regularly over the past decades. It moved from the “vulnerable” category to “least concern” with the exception of two populations : the Oceanian humpback whale and the Persian Gulf. The only species of the genus Megaptera, it is also called "megaptere" (“large wings” in Greek) or jubarte. It is characterized by its color, but especially by its enlarged pectoral fins. The adult measures between 14 and 16 m but can reach up to 18m (the females are slightly larger than the males) for a weight between 30 and 40 tons.
They spend the summer at the poles to feed themselves and thus replenish their fat. Then, they migrate to the tropics and subtropics to reproduce and give birth. The Polynesian population therefore spends the winter in our waters, between May for the first arrivals, and December for the latecomers, the peak of the season being generally between mid-August and the beginning of November. After a long migration of 6000 km, the pregnant females will give birth, others will reproduce in the open sea. They are sight in all the archipelagos, with a predominance for the Austral Islands and the Society Islands, even if they are more and more present in the Tuamotus and more rarely in the Marquesas.
Rather solitary, it is however not uncommon to observe groups rarely exceeding ten individuals in phases of socialization, reproduction, during hunting scenes or during their migration. At birth, the calf has a white to light gray coat and is 3 to 4m in length for a weight of 700 to 1000 kg. He is breastfed by his mother for 6 to 8 months and will leave her after a year, when he returns to Polynesian waters. The suckling phase is essential for the survival of the calf, that drinks 100 to 150 l of milk / day to gain weight from 50 to 80kg / day.
Usually, the odontocetes live in matriarchal groups that can reach several hundred individuals in delphinids. They use sophisticated hunting techniques and each individual has a role to play. They are able to practice echolocation in order to have an acoustic image of their environment. Their range of sound is very expanded, they can emit clicks, pulsing sounds and whistling sounds, in a frequency range up to 40kHz. They have a unique blowhole allowing them to breathe on the surface.
In Polynesia, we find sedentary toothed cetaceans – such as spinner dolphins, often sight in the morning near the coast – but also nomadic or migratory cetaceans. The cetacean population is not uniform and varies according to the archipelagos.
Among the most frequently encountered around Tahiti and Moorea, we can mention the spinner dolphin (Stenella longirostris), the rough-toothed dolphin (Steno bredanensis), the tropical pilot whale (Globicephala macrorhynchus).
The bottlenose dolphin (Tursiops truncatus) is often seen in the Tuamotus and the Marquesas. The Electra dolphin (Peponocephala electra) is widespread in the Marquesas.
Much more rarely, killer whales (Orcinus orca), sperm whales (Physeter macrocephalus), Cuvier’s beaked whales (Zyphius cavirostris) and Blainville (Mesoplodon densirostris), dwarf sperm whales (Kogia simus), pantropical spotted dolphin (Stenella attenuata), Risso’s dolphin (Grampus griseus), pygmy killer whale (Feresa attenuata), false killer whale (Pseudorca crassidens), Fraser’s dolphin (Lagenodelphis hosei).
Weight : 55 to 80 kg
Life expectancy : 20 - 25 years
Physiognomy : tapered body, slender, long and narrow rostrum, triangular dorsal, pointed pectorals
Color : dark bluish gray back, gray sides clear and white belly. Dark line from the eye to the pectoral.
Distribution : tropical and sub-tropical waters.
Food : small fish and squid.
Form social groups up to several dozen individuals. Visible in the morning near the coasts, in the lagoons, and in the bays. They feed in the afternoon and at night, offshore. This species called spinner in English is characterized by its peak speeds (up to 30km / h) and spectacular jumps. Difficult to approach by swimming, they willingly come to play with the bow wave of the boats.
Weight : 130 to 170 kg
Life expectancy : > 35 years
Physiognomy : massive body, short rostrum and unmarked melon, sickle dorsal, pointed pectorals.
Color : Dark gray back, darker dorsal cape. Belly, lips and tip of rostrum white. Medium gray sides with round pink or yellow spots.
Distribution : tropical and temperate, warm and deep waters. Sometimes near the coast. Considered nomadic except in Hawaii and French Polynesia.
Food : fish and squid.
Form social groups of several dozen individuals. Most often discreet, sometimes approaching the coast, they can perform powerful jumps or surf from the bow of boats. They have a very friendly and playful behavior towards boats and swimmers.
Tropical pilot whale
Weight : <4 tonnes
Life expectancy : > 60 years old
Physiognomy : stocky body, no rostrum, globular melon, very wide and curved dorsal fin in males, curved pectoral fins.
Color : black with some gray areas.
Distribution : widely distributed in tropical and temperate waters of the Indian, Pacific and Atlantic oceans.
Food : mainly squid which it finds in depth, generally on the steep slopes of the continental shelf.
Sociable, playful and altruistic, pilot whales are often seen in groups of 10 to 30 individuals but can form groups of several hundred individuals.
There are 7 species of sea turtles in the world (compared to 300 tortoises) and 5 of them can be observed in Polynesian waters, including 2 frequently : the green turtle and the hawksbill turtle. Leatherback, loggerhead, and olive ridley sea turtles are rarely found near the coast.
All sea turtles are threatened with extinction globally. To limit the disappearance of sea turtles, laws have been passed at the international, national and local levels. In French Polynesia, all species of sea turtles are protected and it is strictly forbidden to harm them.
Weight : 120 kg
Food : mainly plants (algae and marine plants) but the young are carnivorous (small crustaceans, mollusks, invertebrates)
It differs from the hawksbill turtle by the shape of its beak, very rounded, its shell with smooth edges and scales between the 2 eyes : it has 1 pair. Like the hawksbill turtle, it has 4 pairs of scales on the sides of the shell. Green turtles regularly lay eggs in French Polynesia, the major sites being in the westernmost atolls as well as in Tetiaroa. Since 2004, a few nests have been observed in Moorea.
Crédit photo : Gilles Siu
Weight : 60-80 kg
Food : sponges
Its name comes from the superposition of the scales of its shell. Its very hooked beak allows it to cut sponges in coral reefs. The toxicity of its flesh would be due to this diet. It is distinguished from the green turtle by the shape of its beak, its shell with irregular edges and the scales between the 2 eyes: it has 2 pairs. Like the green turtle, it has 4 pairs of scales on the sides of the shell. In French Polynesia, they rarely lay eggs.
Crédit photo : Emmanuelle Camallonga
There are 28 species of nesting seabirds in French Polynesia. Some nest on land, others stay at sea to rest and feed. Some are endemic, others protected like petrels (source and copyright: Manu association)
Brown nodi - ʹOio
White-tail tropicbird - Hopetea
Frégate - Otaha
(Fregata ariel / minor)
Baillon's Shearwater - Tira'o
Huped Tern - Tarapapa
Gygis - Tata'e
Brown boobie - Kena
Tahitian Petrel -Noha
Copyright : Alain Petit, Alexandre Champarnaud, Fred Jacq, Thomas Ghestemme, Denise Koenig, Jean-Paul Mutz, Julie Champeau.