To see photographs of the Sperm Whale (Physeter macrocephalus) click here.
Sperm Whale (Physeter macrocephalus)
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protected: © 2002 Kelvin Aitken.
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Sperm Whales belong
to the Physeteridae family of toothed whales.
Calves are born at 3.5-4.5 meters and grow to 12 meters, if it is a female,
or 18 meters if a male.
The mighty Sperm Whale (Physeter macrocephalus) can be found in all oceans
from the tropics to the poles. Females tend to stay together with calves
and sub adults in tropical to temperate zones from 0-40 degrees latitude
with mature bulls tending to be solitary and travelling closer to the
polar ice floes. These mature bulls visit the tropical “harems”
during winter months to breed and socialise. Other groups which are non-breeding
contain bachelor pods of immature bulls or assortments of sub adults.
The appearance of Sperm Whales is unique and, when seen clearly, unmistakable.
They are a toothed whale with heavy dentition in the slender lower jaw
used to grasp their prey. The head is massive, square to slightly bulging
in profile, narrow when viewed from above and taking up at least 1/4,
sometimes 1/3, of the total body length. There is a single blowhole set
on the port (left) upper front corner of the head which blows a conical
spout at a 45 degree angle. The eye is small and set midway down the body
behind the narrow jaw and forward of the small paddle-shaped pectoral
fins. The skin is light to dark brownish-grey with pale patches around
the mouth and genitals and appears to be wrinkled, as if left in the water
for too long. The dorsal fin is a low rounded hump followed by a series
of knuckle-like bumps which are clearly seen when the whale rolls forward
to dive. The tail is broad, sculptured and, when undamaged or newborn,
with a clean edge. Marks on the tail from fights or attacks from killer
whales are used to identify individuals.
Sperm Whales are deep water oceanic dwellers, rarely coming into waters
shallower than 180 meters. They are able to dive to at least 2.8 kilometres
and stay submerged for over an hour. When surfacing they rise vertically,
levelling out at the last minute to blow from their forward mounted blowhole.
The whale then rests, taking a number of breaths over a few minutes, or
anywhere up to an hour, then performs a “stretch”, taking a
breath and submerging completely without diving as they inversely arch
their backs. This is followed by the final dive which always, unless the
whale is harassed, shows the rolling knuckled rear portion of the spine
followed by the huge flukes which are lifted up well clear of the surface.
During their deep dives Sperm Whales feed primarily on squid, including
the enigmatic Architeuthis or Giant Squid as well as various fish species
including deep water sharks, salmon, cod and rays. Their head contains
a giant reservoir of spermaceti oil which is part of their sonar equipment
used to detect and possibly stun their prey. It is this oil for which
Sperm Whales were primarily hunted. Using their blowhole it has been postulated
that the sperm whale can alter its buoyancy at depth by drawing in cold
sea water to cool the oil, thereby partially or completely solidifying
the spermaceti oil to subtly altering their entire buoyancy.
Females care for their young as a group. The mother of a calf can therefore
feed at normal depths with the rest of the pod being present by turns
to care for calves at the surface. When danger threatens the entire pod
forms a circle or “rosette”; tails out with calves protected
in the centre.