Sea mammals like whales, dolphins, and porpoises are highly adapted for marine life. They have torpedo-shaped bodies, lack external ears and hind limbs, and use tail flukes for propulsion. Their bones are lightweight and they have thick blubber for insulation. There are two orders - Cetacea including whales, dolphins, and porpoises which breathe air and give live birth, and Sirenia including manatees and dugongs which are herbivorous and inhabit fresh or marine waters. Cetaceans are divided into baleen whales which filter feed and toothed whales which hunt for food.

1. SEA MAMMALS

2. Mammalian features of Cetaceans
• Warm blooded
• Breathe air with lungs
• Give birth to young ones, that are suckled with milk secreted from
mammary glands
• Hair confined to mouth as whiskers

3. Adaptation of marine mammals
• Torpedo-shaped body, fish-like
• Elimination of neck
• Disappearance of external ears
• Forelimbs modified to flippers
• Absence of hind limbs
• Skin naked, except for few sensory hair-like bristle around the lips
• Locomotion - tail-propulsion, up & down movements of tail-flukes
• Bones are spongy, help in buoyancy
• Blubber (dermal fat) - insulation, storage of food

4. Odontoceti & Mysticeti

5. Adaptations to marine life
• Reducing body’s surface area by 23%
• A highly developed caudal oscillation locomotion that increases the thrust
and efficiency of the lift-based propulsion system
• Bradycardia
• Peripheral vasoconstriction

6. 2 ORDERS
• Cetacea – 14 families, 90 sps
• Sirenia – 2 families, 4 sps

7. Cetacea
• Whales, dolphins and porpoises
• They can be distinguished from fish by absence of gills and horizontal tail
flukes compared to vertical aligned tail fins of fish
• Suborder Odontoceti are carnivorous and eat crustaceans, small fish and small
marine mammals
• Suborder Mysticeti filter plankton and small copepods through large sheets
that hang in their mouth called baleen

8. CETACEA
• Suborder Mysticeti
• Balaenidae
• Neobalaenidae
• Eschrichtiidae
• Balaenopteridae
• Suborder Odontoceti
• Physeteridae
• Kogiidae
• Ziphiidae
• Platanistidae
• Iniidae
• Lipotidae
• Pontoporidae
• Monodontidae
• Delphnidae
• Phocoenidae

9. Balaena mysticetus (Bowhead whale)

10. Eubalaena australis (Southern Right Whale)

11. Caperea marginata (Pygmy Right Whale)
Neobalaenidae

12. Eschrichtius robustus (Gray Whale)
Eschrichtiidae

13. Balaenopteridae (Rorquals)
• Extremely large baleen whales with streamlined bodies, longitudinally
furrowed undersides, small dorsal fin, four-digit slender pectoral flippers,
and broad propulsive caudal flukes; filter-feeding specialists.
• 750-3200 cm.
• Cosmopolitan, inhabiting all the world’s oceans.
• Coastal to pelagic waters from surface to depths greater than 300m.
• 2 genera, 8 sps, 3 endangered

14. Balaenoptera acutorostrata (Common Minke
Whale)
• Smallest and most common, the Minke is dark grey or slaty brown above,
and white or pale grey-brown on its lower side.
• It has a sharp triangular head with pointed snout and a single longitudinal
ridge on the head.
• Most Indian populations have a white band on the flipper, although this is
variable.

15. Balaenoptera acutorostrata (Common Minke
Whale)

16. • It has a tall and slender dorsal fin which is sickle-shaped, small, dark flippers
and a small tail which is notched.
• Underside is pale and mottled with white scars.
• A single ridge on head.
• Silky, ashy baleen plates that number 300-410.
• Gujarat, Kerala and Tamil Nadu
Balaenoptera borealis (Sei Whale)

18. Balaenoptera edeni (Bryde’s Whale)
• A smoky-grey or brown tropical whale with blue-grey, purplish or creamy
undersides, the whale has three longitudinal ridges on its head.
• Their large tail flukes have whitish undersides.
• The throat grooves can be yellowish.

19. Balaenoptera edeni (Bryde’s Whale)

21. Balaenoptera physalus (Fin Whale)
• Asymmetric head coloration – left side of head including lower lip is
uniformly dark gray like body, while right lower lip and right inside of mouth
are white.
• Behind dorsal fin, peduncle is marked by distinct dorsal and ventral keel-like
ridges, features that give it the nickname ‘Razorback’.
• Baleen – front plates on right side are yellowish white and the rest are
striped blue-grey and cream.

22. Balaenoptera physalus (Fin Whale)

23. • Uniformly blue-grey with some mottling. The underbody is the same colour
as the back.
• The head appears broad and U-shaped like a submarine. Rear body is
elongated.
• The dorsal fin is tiny, perched way back and the flippers are large.
• Found normally in the top 100 m of the sea, rarely in the deep.
Balaenoptera musculus (Blue Whale)

24. Balaenoptera musculus (Blue Whale)

25. Megaptera novaeangliae (Humpback Whale)
• It has a slender head with a single ridge, and a number of knobs or tubercles on the
head and lower jaw.
• Longest flippers of any whale, also have tubercles along the edges.
• Dorsal side of body is uniformly black, and ventral surface can be variably coloured,
ranging from black to white or mottled black and white.
• Acrobatic displays
• One of the best vocalizers among aquatic mammals

26. Megaptera novaeangliae (Humpback Whale)

27. hmpback2.wav

28. Odontoceti (toothed whales)

29. Physeteridae (Sperm Whale)
• Largest of the toothed whales with a disproportionately large, box-
like head containing the spermaceti organ complex.
• Flat paddle-shaped fore flippers, conical teeth on narrow lower jaw.
• Most sexually dimorphic cetacean in body length and weight.
• 1100-1500 cm.
• Cosmopolitan (seen off Kerala coast)
• Deep, ice-free oceanic waters.
• 1 Species – Vulnerable.

30. Physeter macrosephalus (Sperm Whale)

32. Kogiidae (Pygmy and Dwarf Sperm Whales)
• Medium-sized toothed whales with under slung lower jaws, blunt squarish
heads, robust bodies tapering abruptly to tail flukes, and spermaceti organs.
• Suction feeding, cephalopod specialists.
• 200-420 cm.
• Cosmopolitan in tropical and temperate seas.
• Shoreward and seaward of continental shelves in waters of 400-3500 m or
more. Both recorded from Thiruvananthapuram.
• Dorsal fin of DSW is taller than that of PSW.

33. Kogia breviceps (Pygmy sperm whale)

34. Kogia sima (Dwarf sperm whale)

35. Ziphiidae (Beaked Whales)
• Medium-sized whales with spindle-shaped bodies and dorsal fins set
two-thirds of the way along the body
• Adult males of most species have a single pair of tusks for male-male
combat, and most juveniles and females functionally toothless.
• 400-1200 cm
• Cosmopolitan
• Deep oceanic waters from ice edges to the tropics.
• 6 genera, 22 species.

36. Ziphius cavirostris (Cuvier’s Beaked Whale)
• Most abundant
• Recognized by goose-beak
shaped mouth and a gently
sloping forehead.
• White or cream-coloured
scars are seen on the lower
side and on the tail.

37. Indopacetus pacificus (Longman’s Beaked
Whale)
• Spindle shaped body with greatest girth around its midpoint
• Flukes are wide in relation to body length and tailstock compressed
laterally
• Colouration dark brown, dark gray or black
• Two throat grooves and single pair of tusks

38. Mesoplodon densirostris (Blainville’s Beaked
Whale)
• This species can be
identified only at close
range by its large, single
lobed flattened teeth.
• Its dark bluish grey body
has a lighter patch on the
underside and a large
number of parasitic-
shark-bite scars all over.

39. Mesoplodon ginkgodens (Ginkgo-toothed
Whale)
• Dark brown, dark gray or black in color
with females and juveniles having paler
ventral surface
• There are 2 grooves on throat and adult
males have single tusk on each side of the
lower jaw
• Males Ginkgo-toothed Whales are
unusual in that they lack the long, pale,
linear scars caused by other males which
are found on most species of beaked
whales

40. Mesoplodon hotaula (Deraniyagala’s Beaked
Whale)
• Colouration is typically dark on
top and light ventrally, with a
paler lower jaw and chin
• 2 grooves on throat and single
tusk
• Species described in 2014

41. Platanistidae (South Asian River Dolphin)
• Medium-sized, stocky river dolphin with very long beak, diminished
eyes, large blunt pectoral flippers and tiny dorsal fin.
• 170-260 cm.
• Indo-Malayan region.
• 1 genera, 1 species, 2 sub species
• Platanista gangetica gangetica – Ganges and Brahmaputra river
basins
• Platanista gangetica minor – Indus river system of Pakistan and NW
India.

42. Platanista gangetica

43. Inia geoffrensis (Amazon River Dolphin)
Iniidae (Amazon River Dolphins)

44. Lipotes vexillifer (Baiji)
Lipotidae (Baiji)

45. Pontoporia blainvillei (Franciscana)
Pontoporiidae (Franciscana)

46. Monodon monoceros (Narwhal)
Monodontidae (Narwhal and Beluga)

47. Delphinapterus leucas (Beluga)

48. Delphinidae (Ocean Dolphins)
• Small to medium-sized dolphins, usually with relatively long beaks,
slender bodies, and prominent dorsal fins. And flukes with a distinct
median notch.
• 140-980 cm.
• Cosmopolitan, inhabitant all the world’s oceans and some river
systems.
• 17 genera, 36 species
• 1 endangered, 2 vulnerable

49. Orcaelaa brevirostris (Irrawaddy Dolphin)
• It is a blunt-headed, beakless,
‘beluga-like’ dolphin that varies in
colour from dark blue-grey to pale
blue.
• It has long and broad flippers with a
curved, trailing edge and a tail with
broad flukes notched in the middle.
It has a neck crease and the neck is
flexible.
• There is an isolated population in
Chilika Lake, Odisha

50. Orcinus orca (Killer Whale)
• Huge dorsal fin, can be
as long as 1.8 m.
• White oval patch behind
the eye.
• Very acrobatic species.
• Prey on other whales.

51. Delphinus capensis (Long-beaked Common
Dolphin)
• Characteristic hourglass
pattern on its body across
the flanks.
• The back can be brownish,
black or purplish, with a
yellow or tan patch on both
sides.

52. Sousa chinensis (Indo-Pacific Humpback
Dolphin)
• A large dolphin, coloured lead-
grey with a pinkish tinge on
the underside, flippers and
flukes, and with occasional
spotting on its body
• It can be identified by its
characteristic hump topped
with a small dorsal fin

53. Stenella attenuata (Pan-Tropical Spotted
Dolphin)
• Body extensively spotted.
• Three bands of grey across
its body.
• Beak is white-tipped and
has white lips.

54. Stenella coeruleoalba (Striped Dolphin)
• More robust in build than
other species of Stenella
• Skin with three-toned
colour pattern
• Pale-gray streak extends
from anterior planks into
cape
• Stripe from beak to black
ring round the eye

55. Stenella longirostris (Spinner Dolphin)
• Very long dark-tipped beak
with a prominent crease
where it joins the forehead.
• Grey dolphin with a creamy
white underside.

56. Steno bredanensis (Rough-toothed Dolphin)
• Head has a unique conical
shape.
• White lips and throat.
• Shape of the body is
reptilian.
• Yellowish or pink blotches
on under belly.

57. Tursiops aduncus (Indo-Pacific Bottlenose
Dolphin)
• One of the commonest dolphins in
Indian waters.
• Grey in colour.
• Short, distinct beak separated
from the forehead by a sharp
crease.
• A tall dorsal fin is darker than rest
of its body and a darker cape may
also be seen.

58. Tursiops truncatus (Common Bottlenose
Dolphin)
• Short and robust beak with
distinct crease separating it
from melon
• Flippers are recurved and
slightly pointed at tips
• Pale gray to black dorsally and
laterally, with pale and
sometimes pinkish coloration
on belly

59. Globicephala macrorhynchus (Short-finned
Pilot Whale)
• It has an off-white belly patch
on a dark grey body, a W-
shaped grey patch on its
throat, and a grey or white
diagonal stripe from its eye to
the dorsal fin.
• Pale throat patch.
• Very social, travels in large
pods.

60. Grampus griseus (Risso’s Dolphin)
• Dome-shaped forehead with a
crease that runs from the centre
to mouth line.
• It is almost beakless with body
heavily scarred with white
streaks.
• Dorsal fin of the female is almost
as tall as a Killer Whale’s and has
a rounded edge.

61. Peponocephala electra (Melon-headed
Whale)
• A dark, small dolphin with a
torpedo-shaped body. The
head becomes more bulbous
with age.
• The flippers are pointed and it
has a small inconspicuous
grey-white belly. It also has
white lips.

62. Lagenodelphis hosei (Fraser’s Dolphin)
• Back and flanks are dark grey or
brown and belly, throat and
lower jaw are white sometimes
with pinkish tinge
• Beak tips and lips are dark, dark
lateral stripe extending from
face to urogenital area

63. Feresa attenuata (Pygmy Killer Whale)
• Head is bulbous and rounded
with no visible beak
• Dark grey to black skin with
pale grey to white lips
• A narrow white patch runs
ventrally along the body
widening at urogenital area

64. Pseudorca crassidens (False Killer Whale)
• Slender in shape with rounded
head and no beak
• Slightly ‘S’ shaped flippers
• Tailstock is deep and grooves may
be observed in urogenital area
• Skin dark gray to black in colour
with pale-gray patch on chest

65. Phocoenidae (Porpoises)
• Small, relatively robust with short and poorly defined beaks, small spade-
shaped teeth.
• All oceans and some rivers in East and South Asia.
• Shoreward of the continental shelf, mostly shallow waters less than 180 m
deep, 2 sps in deep oceanic waters and 2 in rivers.
• 3 genera, 7 species.
• 1 CR, 2 VU

66. Neophocaena phocaenoides (Indo-Pacific
Finless Porpoise)
• As the name indicates, it has no
fin on its back and possesses
only a dorsal ridge with
tubercles.
• The head has a large, blunt
melon and a depression behind
the blowhole.
• The tail fluke is deeply notched
and has a concave trailing edge.

68. Order Sirenia

69. • Only Aquatic herbivorous mammals
• Have only six vertebrae
• They do not have canines, only incisors (first pair tusk-like in males) and
molars
• Dugongs have a notched tail and manatees has a rounded fluke

70. Manatees Dugongs
• Live in freshwater
• Manatees have only 6 neck
vertebrae
• Horizontal teeth replacement
• Tail is horizontal and paddle shaped
• Blubber help them fast for even six
months
• Three species in the world, none in
S Asia
• Live in marine water
• Tail has concave trailing
edge
• Feed on sea grass and
marine rhizomes
• “sea pig” or “sea cow”

72. Trichechidae (Manatees)
• Medium to large sirenians with pectoral flippers, no external hindlimbs, and
spatulate (spoon-shaped) tail flukes.
• 250-390 cm.
• Nearctic, Neotropical, and Afrotropical Regions.
• Tropical and subtropical shallow Atlantic coastal waters, lagoons, estuaries,
large rivers and tributaries where passage permits.
• 1 genus, 3 species, 3 VU

74. Dugongidae (Dugong)
• Medium-sized sirenian with pectoral flippers lacking nails, no external
hindlimbs, and a whale-like tail fluke with a median notch.
• 200-330 cm.
• Subtropical and tropical Indo-West Pacific waters.
• Coastal and island waters with seagrass meadows.
• 1 genus, 1 species, VU
• Sexes can be differentiated by the presence of tusks and heavy scarring of
body in males.

75. • Are voracious feeders of seagrass and in India they are known to feed on
Cymodocea serrulata, Halodule uninervis, Halophila ovalis and Enhalus
acoroides
• Dugongs dig up seagrass beds and eat tubers too
• Long life span (70 years), low reproductive rate and high investment in
young
• Dugongs are known to chrip, trill and whistle