Environmental Engineering Reference
In-Depth Information
Act (1972) has stated about the protection of the
species, and several agencies (e.g. Chilika
Development Authority) have undertaken several
initiatives to conserve the species through creation
and ecorestoration of habitats.
Suborder Mysticeti includes the whalebone or
baleen whales, who have no teeth. They are not
deep divers and are mainly
Order Carnivora
This order includes land predators ranging from
dogs and cats to bears and weasels, but the sub-
order Pinnipedia (that includes seals, sea lions
and walruses) are exclusively marine. Unlike the
cetaceans, the gregarious pinnipeds leave the
ocean for varying periods of time to mate and raise
their young. Pinnipeds have four limbs that are
modi
lter feeders and feed
actively on krill, few metres below the surface.
They have baleen plates, which help in screening
plankton engulfed along with sea water. The
baleen consists of keratin
ippers. Although they are more at
home in the water, they possess the capability to
come on the land, mainly to mate, give birth, and
moult. Their bodies are spindle-shaped and many
species have several layers of fat under the skin to
provide insulation. Seals are important members
of suborder Pinnipedia. Seals have smooth head
with no external ear
ed into
fl
bres that are fused
together and function to strain the plankton,
mainly krill on which the animal feeds from the
water. Baleen whales include right whales,
rorquals and grey whales. The largest animal is
the blue whale, which requires 3 metric tonnes of
krill per day during the feeding season. Some
species migrate annually from polar to tropical
waters and back. Some common examples of
baleen whales are humpback whale, bowhead
whale, minke whale, right whale,
aps, which enhances further
streamlining of the body. They are graceful
swimmers and generally their diet consists of
small
fl
shes. The rear appendages of hind limbs are
fused partially and always point back from the
hind end of the body. The elephant seal, named for
its long snout and large size, holds the diving depth
record for air-breathing vertebrates. Eared seals,
which include fur seals and sea lions, have visible
external ears. True seals andwalruses lack external
ears. Eared seals primarily use their front limbs to
propel themselves through the water. True seals
use their hind limbs and walruses use a combina-
tion of both. The hind limbs of eared seals can be
rotated at right angles to the body axis and act as
legs on land. Sea lions have a coarse coat of
nothing but hairs, while fur seals have a thick coat
of fur. Fur seals were at times relentlessly hunted
for their coats, but now they are protected by
international law. The populations of sea lions are
mainly concentrated in the Paci
n whale, sei
whale and gray whale.
The Bay of Bengal is a bay that forms the
north-eastern part of the Indian Ocean. It occu-
pies an area of 2,172,000 km 2 . It is bordered by
India and Sri Lanka to the west, Bangladesh to
the north, and Myanmar and the southern part of
Thailand to the east. Its southern boundary
extends as an imaginary line from Dondra Head
at the southern end of Sri Lanka to the northern
tip of Sumatra. A number of large rivers
Gan-
ges, Brahmaputra, Irrawaddy, Godavari, Maha-
nadi, Krishna and Cauvery
ow into the Bay of
Bengal. The Ayeyarwady River of Myanmar also
fl
fl
uenced bay
sustains diverse population of marine mammals.
Schools of dolphins can be seen, whether they
are the bottlenose dolphin (
ows into the bay. This river-in
fl
c coast. Califor-
nia sea lions (
Zalophus californianus
) are found in
the near-shore waters along the Paci
c coast from
Vancouver Island, British Columbia to Baja
Mexico. North of southern California, the hauling
out grounds are occupied by males only, who
migrate north for the winter. The females and their
pups remain in California all year. Males often
reach 850 pounds and 7 ft in length and females
can acquire a weight of 220 pounds and up to 6 ft in
length. They are extremely social animals. The
main haul-out areas along the Oregon coast are
Tursiops truncatus
),
pantropical spotted dolphin (
Stenella attenuata
)
or the spinner dolphin (
).
Tuna and dolphins are usually residing in the
same waters. In shallower and warmer coastal
waters, the Irrawaddy dolphins
Stenella longirostris
(Orcaella brevi-
rostris) can be found. A list of marine mammals
sighted in and around the bay is highlighted in
Table 2.18 .
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