Humpback Whales

To look up into the mountains and see the steam rolling from a mountain stream
on a cold winters morning is a beautiful sight. However, to look out over the
horizon and see the white spray of salt water coming from the blow of a huge
humpback whale is much more exciting sight and a whole lot warmer. The first
time I had the opportunity to see the ocean was on a vacation to California,
when I was about 15 years old. It was even better than I had dreamed it would
be. The different animal in the ocean, the color of the water, and the warm sand
between my toes was what made me take a vacation to Hawaii. When I first saw the
humpback whale I was amazed at their huge size and how they could breach out of
the water so gracefully. It is as if they were trying to play or show off. So
when we were asked to choose a favorite animal, I had no problem deciding on the
humpback whale. The hump-back whale gets it’s name from the distinctive hump
in front of the dorsal fin and from the way it raises it’s back high above
water before diving. They are a member of the order Cetacea. This order is of
aquatic mammals and the humpback belongs to the suborder of the Mysticeti. The

Mysticeti are the baleen whales, which have three families and several species.

The family in which the humpback belongs is the Balaenopteridae, the true fin
backed whale. The thing that separates this genus from the other fin-backed
whales is the pectoral fins, which grow in lengths of about 16.4 feet. This

Genus is called Megaptera meaning great wing (Tinker 290). There was a
controversy over the species name in the late nineteenth and early twentieth
century. In 1932, Remington Kellogg finally settled the matter with Megatera

Novaeangliae (Cousteau 84). The common English name is the humpback whale. The
humpback whale lives in both the Atlantic and the Pacific oceans. Since we live
in the Pacific I’ll be discussing the humpbacks of the North Pacific. They
migrate from North to South. In the months of July through September they gather
in the Aleutian Islands, Bering Sea or the Chukchi Sea. They head south for the
winter. They go to one of three areas: Between the Bonin Islands, the Marianas

Islands, the Ryukyu Islands and Taiwan; The Hawaiian Islands, and along the
coast of Mexico (Tinker 291). One of the reasons these whales go north is for
feeding. They have a short food chain compared to most mammals. Phytoplankton
turns sunlight into energy and this energy is consumed by zooplankton. Small
fish eats the zooplankton and phytoplankton. The whale in turn eats the fish.

The chain is complete when waste products or dead whales decompose. They have a
very short time frame in which they eat compared to the twelve months out of the
year. They have not been seen feeding in Hawaii. It seems that they only feed
during the summer months up north. During the fasting periods, in Hawaii, they
survive on their blubber. They mix their diet with copepods, krill, and small
fish, primarily herring and capelin. They are considered filter feeders, using
baleen plates to filter out their food. They take huge amounts of water into
their mouth using a gulping method and then when they push the water out, they
put their tongue up so the water must pass through the baleens. The food becomes
trapped and falls toward the rear of the mouth. The two gulping methods humpback
whales use are lunge feeding and bubble net feeding. Lunge feeding is used when
food is abundant. The whale simply swims through the prey with its mouth open
engulfing the prey. They can do this vertically, laterally or inverted. This is
done toward the surface of the ocean. Bubble net feeding is used when the prey
is less abundant. The whale dives below the prey and discharges bubbles from its
blowhole. As the bubbles ascend they form a net that disorients the prey. Then
the whale swims upward and fills his mouth with the net of fish and bubbles
(Kaufman 55). Humpbacks have ventral grooves in their throat that expand
allowing an enormous amount of water to be gulped. Humpbacks consume nearly a
ton of food in a day’s time during their feeding season. The humpback
whale’s stomach consists of three chambers and the duodenal ampulla much like
a cow. The three stomachs are separate from each other. They have small and
large intestines, a rectum, caecum and an anus. These organs are very similar
and work much the same as in most mammals. The digestive glands of a whale are
somewhat different. They do not have salivary glands that are functional. The
liver is bilobed and the gall bladder is absent. The pancreas however resembles
that of most other mammals (Tinker 63). Mammals, which live in the sea, have a
continued problem of dehydration. Humpbacks get water from the food they eat and
during their fasting periods they get it from their blubber. However, the
salinity in the whale’s bodily fluids is much higher than land mammals but it
is still lower than the seawater. This creates a problem. They are in danger of
losing too much water. In order to maintain a proper balance the whale passes
large quantities of highly concentrated urine. The kidneys are specialized to do
this. The feces also permit discharge of salt. However, few studies have been
done on humpback’s feces or urine (Kaufman 31). As humans we can breathe
either from our mouth or nose. This is not the case of the humpback whale. The
whale can neither inhale nor exhale through their mouth. The nasal openings of a
whale are known as the blowhole. There are two paired openings at the top of the
head. The holes are closed and made watertight by two plugs (Tinker 65-68). If
you weighed ten elephants that would be the average weight of one humpback
whale. The male and female whale alike weigh between thirty and fifty tons. This
weight will vary depending on the season. While fasting in Hawaii the weight
will be much less. The calves are born in January and early February as a result
from the previous years mating. They are born at approximately fourteen feet
long and end up as long as sixty-two and a half feet with an average of fifty
feet. The calf, a young humpback, will drink one hundred pounds of milk each
day. This milk is very rich compared to domestic animals. The calf will begin to
nurse soon after birth from two nipples located on either side of the vaginal
slit. (Coustea 86). After birth they grow very fast. By March they more than
double their weight and are ready to begin their migration north. They will wean
in about five to seven months from birth. Whales are not monogamous. Males have
been seen romping and playing with females and it is thought that sometime
during this romping and playing mating occurs. It has never been determined
when. Over eleven to twelve months later, back in the same waters, the female
gives birth. Usually they do not have calves each year, however, it is possible.

The birth of twins has never been recorded however it is possible. Sexual
maturity is as early as four years old for both sexes. They live for about
thirty years but studies have shown they can live much longer. Using a "wax
plug" system, much like the system of the rings of a tree, one whale was
thought to have been fifty-eight years old before it died. (Balcom 15-19).The
reproductive organs are located internally. The male’s penis is withdrawn into
a slit. An erection of the penis is accomplished by a pair of muscles, much like
that of cattle and horses. The female’s ovaries produce single celled eggs.

When the egg is mature it is discharged into the fallopian tubes, a process
known as ovulation. At this time if mating occurs and the egg is fertilized with
sperm from the male the birth of a baby whale is on the way. (Kaufman 31-33).

Most mammals usually have five sense organs. The whale only has three. Touch,
which is located in the skin, is the sense that can feel pain, heat, cold and
vibration. They also have feelers called vibrissae. These feelers are very
similar to whiskers on a domestic cat. The vibrissae are located in rows on the
end of the lower jaw, on the sides of the lower jaw and on top of the head.

Sight is the sense that allows the whale to see. The shape of the whales eyeball
tend to make them far-sighted below the surface and nearsighted above the
surface. Since the eyes are located on either side of the head it makes it
impossible for their visual fields to overlap, therefore, they do not have depth
perception. Their auditory sense, or hearing, is very important because in the
ocean the visibility is poor. Good hearing is used to help locate food, hear the
approach of enemies, and communicate with each other. Their ears are gone and
only a slit appears midway between the eye and the base of the flipper. The
sense of smell and taste are not present like in most mammals (Tinker 81-85).

Due to the size of these enormous animals they have few predators. Man is their
worst enemy. However, they do have confrontations with other whales. Some of the
defenses used are, filling their mouth with water or air so to bluff the invader
into thinking they are bigger than they are. As a second line of defense they
will use the head and fins as weapons. They also use their huge body as a
defense mechanism by positioning themselves between the invader, like a boat,
and mother and calf. (Kaufman 93-115). A more subtle defense is counter shading
, where the top of the whale is dark which makes it harder to see from above
looking down and the bottom is light so looking up it is hard to see against the
lighter surface of the ocean. Humpbacks produce a wide range of sounds. Often
these sounds are long and complex that are repeated for hours. O.W. Schreiber
recorded the first sounds here in Hawaii in 1952 on the basis of recordings
collected at the U.S. Navy Sound Fixing and Ranging Station. One whale sung a
song for fourteen hours without stopping. Since singing is done primarily during
the mating season it is thought to serve a reproductive function. It has been
shown that only the males sing this song. It may also attract females, scare
away other males, or maintain the distance between singers. Males and females
alike make other sounds, which are associated with feeding and socially active
groups (Kaufman 73-77). The whale’s pectoral fins is not used for propulsion
but to balance and steer. The tail or fluke is used to move this massive mammal
through the water. The muscle caudal peduncle move the fluke in an up and down
direction, which propels the whale through the water (Tinker 55). The worldwide
population of humpbacks is estimated between ten thousand and fifteen thousand
animals. This count is down from over one hundred and fifty thousand last
century. (Dietz 39). Man has hunted the whale close to extinction. The good news
is that we have bans against killing whales in most waters. Hopefully we did
this in time to save them from extinction. It would be a true shame if my
grandchildren could not enjoy these wonderful creatures.