Humpback Whales Essay, Research Paper

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.