FREE ESSAY ON HUMPBACK WHALES

HUMPBACK WHALES

The Humpback Whale
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.