World_of_Animals_Issue_46_2017

Meet the family
Dolphins
After making their way back into
the water 50 million years ago, over
40 species of dolphin roam oceans
and rivers all over the world today
Orca
The deadliest relative
This is one of the most successful predators on the planet, killing around
95 per cent of the prey it sets out to catch. That’s immensely impressive
compared to a lion’s measly 17 per cent success rate. Orcas charge at prey
at 65 kilometres (40.4 miles) per hour before biting with their 40 to 50
teeth, which can reach ten centimetres (four inches) in length. But their
physical attributes aren’t the most dangerous thing about the aptly named
killer whale. Orcas have intelligence almost beyond belief, and this stems
from their close social bonds. Calves never leave their family pod and are
cared for by their parents, siblings and grandparents. Young orcas are
taught by their parents and given the chance to finish off prey weakened
by the adults. Teams co-ordinate and communicate to hunt animals on ice,
land or in the water by any means necessary.
orCa
Orcinus orca
Class Mammalia
Territory Global
diet Fish and marine
mammals
lifespan 80 years
adult weight 5,400kg
(11,905lb)
Conservation status
DATA DEFICIENT
The dorsal fin on the back contains
no bones – it’s pure cartilage.
Captive fins are prone to collapse
after giving into gravity because the
orcas spend an inordinate amount
of time floating at the surface of
their shallow tanks.
Spinner dolphin
The family acrobat
Aptly named, these dolphins can leap three metres (9.8 feet)
clear of the water and perform
spinner dolpHin
Stenella longirostris
Class Mammalia
Territory Tropical oceans
diet Fish and squid
lifespan 30 years
adult weight 59-82kg
(130-180lb)
Conservation status
DATA DEFICIENT
seven 360 degree twists before
landing. The rotation begins
underwater and once the animal
breaches the surface it can
twirl faster without the sea’s
resistance. There are lots of
theories to explain this spinning
but there isn’t a single accepted
explanation. They may be
attempting to dislodge remoras,
which are fish that attach to the
bodies of other sea creatures to
hitch a free ride. These dizzying
displays may also attract
mates or display dominance.
Alternatively, the loud splashes could communicate the
position of dolphin groups to others, or maybe it’s just for fun.
This species visits shallow waters to rest and socialise on a
regular basis, especially in the summer when the calves arrive.
The pectoral fins contain five long ‘finger’
bones and help the spinner dolphin get lift
when attempting a jump.
Hourglass dolpHin
Lagenorhynchus cruciger
Class Mammalia
Territory Southern Atlantic
diet Small fish and squid
lifespan Unknown
adult weight 94kg (207lb)
Conservation status
LEAST CONCERN
The black and white colouration
confuses predators. It makes
it difficult to tell where one
animal ends and the next
begins or even which direction
the group is travelling.
Hourglass dolphin
The sub-zero hunter
These rare animals are found in small groups in the freezing waters of
the Antarctic, following fluctuating cold currents. Like most other species
in the family, hourglass dolphins use echolocation to search for food,
beaming out sounds into the water and listening out for the echo. These
animals produce such high-pitched sounds that they are able to travel
twice as far as those produced by other dolphins. This is probably the
result of their ability to dive to depths of at least 1,500 metres (4,921
feet), far too deep for sunlight to penetrate, meaning the dolphins
have to rely on their hearing rather than their eyesight.
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