All whales, dolphins and porpoises
Although the cetaceans include the largest animals in the world, there are many small forms as well. Because they live completely in the water they are often thought to be fish, but they are true warm-blooded mammals which have lost their legs and most of their hair, and acquired fins and other modifications for living in the sea. They still breathe air, give birth to live young, and feed them on milk.
If not seen well, some whales could be mistaken for sharks, as the dorsal fin sometimes appears similar. However, amongst other differences, whales have a blowhole on top of the head, visible when the animal breathes, and horizontal tail flukes instead of a vertical tail.
Whales and dolphins are often difficult to identify, as they are usually hard to see well in the water. Even experienced observers familiar with the behaviour of the animals cannot identify every cetacean seen, and it can be especially difficult for a beginner. However, some species are quite tame, allowing good views, while others show themselves several times, eventually allowing enough to be seen for identification.
Very few people have studied whales around Borneo, and the few confirmed records available are mostly stranded specimens. However, there appear to be many small porpoises and dolphins in the offshore waters, and several species of large whales are likely to pass through Bornean waters at least occasionally. Because of this, all of the species known to occur in the tropical Pacific or Indian Ocean are included here, even if they have not definitely been recorded from Bornean waters.
SEI WHALE (Balaenoptera borealis)
The rorquals include some of the largest whales and can be recognized by their huge size and small dorsal fins near the back of the body. They feed by filtering food and water through huge baleen plates in their mouths. They can often be distinguished from the Sperm Whale at a long distance by the shape of the spout when they breathe - tall and conical or low and bushy as opposed to the Sperm Whale's spout which is angled forwards and to the left. This, however, is less conspicuous in warm tropical air.
The various rorquals can only be separated when they are seen well. Key features include size, the shape and position of the dorsal fin, the shape of the head and the coloration. The size and colour of the baleen can be helpful for distinguishing dead whales found stranded on beaches.
Measurements. TL 12-14 m, maximum 17-21 m. Females larger than males.
Identification. Body uniform dark-grey with ovoid white scars; belly whitish. Conspicuous dorsal fin about one third of way forward from tail; angle of front of fin usually more than 40o. Single prominent ridge from blowholes to front of rostrum; tip of snout slightly down-turned in profile. Fin usually visible at same time as blow. Baleen uniform grey-black with white fringes; sometimes a few half-white plates near front of mouth.
Similar Species. Fin Whales, B. physalus, have a more shallow dorsal fin visible just after the blow, and asymmetric white lower lips; Bryde's Whale, B. edeni, has a slightly smaller more pointed fin and 3 ridges on top of head.
Ecology and Habitat. Rarely dives very deeply, often feeding near the surface. Eats krill, squid, and small fish. Often in small groups. Migrates annually from high-latitude feeding grounds to low-latitude wintering grounds.
Distribution. One specimen stranded at Pusa, S. Saribas in Sarawak.
Common Dolphin (Delphinus delphis)
This family includes all of the well-known dolphins as well as the large Killer Whale. They have rows of peg-like teeth in both jaws, well developed dorsal fins and often a distinct beak.
Measurements. TL up to 2.5 m, but usually less than 2.3 m.
Identification. Black brownish-black to black, belly white; sides with broad criss-crossing stripes of buff or grey and white; dark V-shaped saddle below dorsal fin distinguishes from all other dolphins if seen clearly. Dorsal fin tall and triangular, all black to white with a black border. Beak long and narrow, usually black but sometimes with a white tip.
Similar Species. the Striped Dolphin, Stenella coeruleoalba, has thin dark stripes from the eye to the anus and the eye to the flippers.
Ecology and Habitat. Feeds mostly at night on deep-sea fish and squid. Very active during the day, often jumping and playing in the water.
Distribution. Throughout the tropical and sub-tropical seas. Sight records off Sabah (in the east and north) and Sarawak.
Finless Porpoise (Neophocaena phocaenoides)
Similar to dolphins, but with no beak. The only species found in Bornean waters has no dorsal fin.
Measurements. TL 1.6-1.9m.
Identification. Uniform slate grey, sometimes very pale - never black except after death. Rounded head; no dorsal fin.
Similar Species: all other potentially similar species such as the Irrawaddy Dolphin, Orcaella brevirostris, and the Hump-backed Dolpin. Sousa chinensis, have a distinct dorsal fin and are usually larger.
Ecology and Habitat. Eats small squid, prawns, and small fish. Found in shallow coastal waters and river estuaries in small groups or singles.
Distribution. reportedly common in estuaries of northern Sarawak, formerly also in southern Sarawak.