Blue Whale - Balaenoptera
also called: Sulphur Bottom
Whale - Sibbald's Rorqual
Blue Whale Statistics
27m (89ft) males / 33.5m (110ft) females
weight: 200 tonnes max. / 110-120 tonnes average
Life span: 90 years
uncertain estimated at 5 - 15 years
Birth length: 6-7m (20-23ft)
Birth weight: 3.3 tonnes
Distribution: worldwide, but separated
into distinct stocks
Current world population:
up to 12,000 / pre-whaling - 200,000, maybe 300,000
whales are one of the rorquals, (the blue was initially
studied by Scottish naturalist Sir Robert Sibbald in 1694 hence
the title "Sibbald's Rorqual"). Rorquals are characterised
most obviously by the longitudinal pleats that allow the throat
to expand enabling the whale to take in huge gulps of food-laden
water before expelling the water through the baleen plates which
filter out the food - small fish or plankton - and then gulping
it down. The pleating increases the volume of water in a single
mouthful to increase by an estimated 6x over non-expanded size.
There are between 55 and 68 of these pleats or ventral grooves
that extend as far down as the navel. The whale looks like one
of those weird deep-sea gulper fish when it has a mouth-full
before it expels the water (but bigger!).
At the height
of the feeding season in Antarctica an adult blue whale consumes
3-4% of their own body weight in krill per day. For a 150 tonne
blue whale, that is 6 tonnes of food a day consisting of some
6 million individual krill. When the days are long and the
food is abundant the feeding goes on almost without stopping,
blue whales are thought to feed for 8 months of the year and
then fast for the other 4 living off their reserves of fat or
blubber built up during the days of plenty.
Blue whales are
light grey/blue to dark grey while at the surface, but seen
underwater they are a luminous aqua blue, they can be distinguished
from other large whales as they have mottled skin. The whalers
would sometimes refer to the blue whale as the "sulphur
bottom". When they have reached Antarctic waters in the
austral spring, day light is near to if not already 24 hours
a day and phytoplankton are growing wherever they can. This
means mainly in the water column, but some species of diatom
algae start to grow on the whales themselves, the blue whale
and the green algae give a yellow effect so earning the name
Unlike some other
whales, blues are almost completely free of external parasites
and hangers-on such as barnacles, their swimming speed probably
makes it impossible for them to attach and hang on unlike with
the slower moving whales such as the right whales.
There are three
recognized subspecies of the blue whale. The pygmy blue
whale (B. m. brevicauda) is found in the Southern Hemisphere
and northern Indian Ocean. This is shorter with a maximum length
of about 24m ("pygmy" is a relative term when it comes
to describing blue whales!) and has a relatively larger head.
It is possible to distinguish pygmy blue whales from other blue
whales at sea if a good view can be achieved. The body shape
is more 'torpedo-shaped' (with a relatively narrower
head) for the "standard" blue whale.
The Northern Hemisphere
subspecies is known as B. m. musculus these are around
23-27 m long, females being larger than the males. The Antarctic
blue whale subspecies, B. m. intermedia is the largest
of all, and measures up to 29 m, although a specimen over 33
m has been recorded.
Size and other statistics
Blue whales hold just about every record going for animal
size. They are larger than any dinosaur ever was, growing
to such a huge size by tapping the food chain low down near
the source of energy and by being aquatic so their great bulk
is supported by the water. It is very difficult to measure how
heavy such huge animals might be, it isn't possible to pick
them up and weigh them or walk them onto some kind of scales
or weighbridge like we could with other animals. Any weights
are therefore estimates. The original figures for the weight
of blue whales were determined in 1926 by the weighing a part
at a time by a whaling company of an individual being processed.
This set a benchmark and with more modern methods of estimating
volume, so estimates can be arrived at.
Average fully grown blue whales are around 100-120 tonnes and
particularly large individuals have been estimated at 200 tonnes!
An average blue is about the equivalent of about 25 fully grown
African bull elephants. Another way of looking at it is that
an elephant is to a blue whale as a rabbit is to a human.
All figures about blues are awesome, their circulatory
system pumps 10 tonnes of blood through the body using a one
tonne heart the size of a small car (such as a VW Beetle). A
child could crawl down the whales' main blood vessel, the
aorta. In its development, a blue whale calf can drink 100 gallons
of its mother's milk and gain 200lbs per day - that's
over 8lb an hour!
A blue whale laying on its side would be 10 feet (3m) high and
the width across its flukes (flippers) about 20 feet (6m), a
full grown man standing on tip-toe and reaching as high as he
could wouldn't reach as far as from the tip of one fluke
to the middle of the two. It's fins are the size of large
dining tables and its 3-5 tonne tongue would overload a good
life expectancy of blue whales is particularly difficult
to estimate, it is certainly beyond 25 years and has been estimated
as from 30 to 80 years with suggestions of as much as 100 years.
The "blow" of a blue whale is a powerful blast of
water as thick as a mans arm and reaching up to around 6m.
One of the most
impressive things about blue whales are the sounds that they
make. Whales communicate regularly by sound with each other
when they are in groups or "schools". Sound travels
far better in water than in air and while whales do not have
any external ears, they have a very good sense of hearing, their
flesh and bone carry the sound to their ears that are "buried"
in their skull.
As small animals
tend to make high pitched squeaking sounds, so larger animals
make deep rumbling sounds. Divers have reported blue whale vocalizations
as being "felt" more than heard. Blue whales make
very deep low-pitched sounds that have been recorded as high
as 188 decibels (at 1m from the sound source) - far and away
the loudest sound made by any animal. A passenger jet at take
off makes a noise that is 120 decibels. Blue whales sound can
be heard at a distance of over 500 miles (800 kilometres) -
as long as you can hear that frequency.
despite almost every other measurement being so large, a blue
whale's oesophagus or gullet is a mere 4 inches or 10 cm
in diameter, so it would have problems swallowing a whole grapefruit,
this could never have been the whale that swallowed Jonah.
Blue whales may be found world wide, though
there are two distinct populations a northern hemisphere population
and a southern hemisphere population. Each population spends
the summer in high latitudes, Arctic or Antarctic feeding continually
and growing fat on the high productivity that long days bring
to coastal waters. In the winter months in their respective
hemispheres, they migrate to tropical or temperate waters to
mate and calve. As the two hemispheres have opposite seasons,
so the two populations do not intermix and remain distinct.
In addition to this, there are two separate northern populations,
one in the Pacific and one in the Atlantic.
It is generally the larger and older animals
that will venture into the highest latitudes.
a dive, blue whales lift their flukes only slightly out of the
water. They may blow frequently, every 10 to 20 seconds for
2 to 6 minutes, diving for 5 to 20 minutes (although they are
able to stay under for longer). Short dives (10-20 minutes)
are most common, although dives of up to 30 minutes have been
recorded. Blue whales are generally fairly shallow divers to
no more than 100 m depth, as that is where their prey is. It
is believed that they can dive to 500 m. Blue whales have occasionally
been observed breaching.
Blue whales are
usually encountered alone or in pairs. Like the other large
baleen whales, it seems that they form schools that are loose
associations mainly in areas of high food concentration. In
such circumstances many animals feeding together can aid each
others effectiveness. Mixed schools of blue and fin whales have
Blue whale - photo courtesy NOAA
Blue whale blowholes - the whale is swimming away from
the camera, note how the blowholes
are aligned so as not to be filled with water when swimming
- photo courtesy NOAA