Monk
Seal
Three Polynesian Aquatic Animals
Joana A. Cordoba
Monk
Seal
Curious Facts
The monk seal is one of Hawaii’s favorite pinnipeds ( Latin for
“fin-footed”) and keeps strong ties with its terrestrial ancestors, the bear
and dog. Pinnipeds are one of the thirty-four species of seals related to
mammals. The ancient Hawaiians had
named the seal Ilio-holo-i-ka-uaua, meaning “dog that runs rough waters”.
The native Hawaiian seal referred to is the Hawaiian monk seal; it is one
of the many interesting native species of the Hawaiian Islands.
The Hawaiian monk seal is mostly recognized for its monk like behavior of opting for solitude rather than companionship like other seal species. It is characterized mainly by its large eyes, prominent snout, and four swimming flippers. Its population is estimated to be between 1,500 and 1,200, making this an endangered species. An adult monk seal can weigh between 400 and 600 pounds and its length can extend up to seven feet. Curiously, in the monk seal species the female is much larger than the male. Their life expectancy is a maximum of thirty years.
The Hawaiian monk seal likes to feed upon invertebrates and fishes, though while breeding in the Northwestern Hawaiian Islands they often include octopuses, eels and spiny lobsters common around the shore in their diet. The male seals travel near the Northwestern Islands during the spring and summer months to mate. They mate with more than one female seal, making this species polygamous. Their polygamous relations are partly due to their uneven sex ratio, as are more males than females. The uneven sex ratio along with the fact that female seals can only be considered sexually mature at the age of six contributes to the low reproductive rate.
Reproduction
Female Hawaiian monk seals give birth every two years, one pup at a time.
The pups are usually born between March and June, a year after
conception. The mother seal nurses
her pup for six weeks. During those weeks the mother seal lives off the fat
stored, so as not to leave her pups unattended.
The monk seal mothers have been known to exchange their pups.
It is also known that a mother seal can abandon her pup if disturbed by
humans. Due to their low
reproductive rate and their endangered situation, as well as the mothers’
sensitivity to disturbances, careful measures need to be taken to ensure this
species survival.
Threats
There are five factors affecting the Hawaiian monk seal population.
One is hunting and human disturbances, as seals are hunted mainly for
their oil and pelts. A second factor affecting the monk seals’ population is
fishing. Fishing represents a
threat to monk seals because they get tangled in the fishnets used for catching
fish. Another factor is one nature
provides, sharks, which are the main predators of monk seals, particularly the
younger seals. A fourth factor
affecting the population of monk seals is the disease Ciguatera.
Ciguatera affects monk seals only if they ingest fish with high
concentrations of toxins (this disease has also been known to affect humans).
The last factor affecting the monk species comes from within the species
itself, and it is an event known as mobbing.
Mobbing consist of violent attacks performed by many adult monk males
upon female monks and their pups in attempts to mate; this behavior has been
known to occur by individual male monks also.
Protective measures being taken to assure the survival of the monk species include federal laws and regulations. Some regulations go as far as protecting the monk seals from harassment. Regarding the fishing factor, which poses a problem for monk seals, distinctive measures have been take to make fishnet illegal, or at least restricted. All of these measures are being enforced and reinforced in order to preserve this very important Hawaiian native species, the Hawaiian monk seal.
Green
Sea Turtle
Curious
Facts
The Hawaiians call
this turtle “Honu,” the green sea turtle.
Unlike land turtles, it cannot retract its head into its shell.
It is also unusual in that, being primarily aquatic, it requires the capacity to
retain oxygen when sleeping at the bottom of
the ocean. Green sea turtles can
remain under water for up to 2 hours without breathing by
efficiently using the oxygen stored in their lungs. This unique system,
however, is only exhibited by older green sea turtles; the juveniles only acquire the system with maturity.
Another adaptive mechanism allows the green sea turtle to keep
their bodies from dehydrating despite their salt water habitat.
In order to maintain the proper amount of salt within their systems they have
developed a salt
gland. The salt gland is located
near the eye and it secretes the excess salt from the body in the form of tears.
So when you see a green sea turtle, you often will notice its constant stream of
tears. Another interesting fact
about the green sea turtle is that the older ones are herbivores
while the younger ones are carnivorous. It
is still unknown how long green sea turtles may live--some live beyond, and
perhaps far beyond, 100-years-old. Although heavy--an adult can weigh well
over 500 pounds--they can travel relatively swiftly, up to 35 mph, when in the
water.
Reproduction
Sea turtles reach sexual maturity at the average
age of 25. Adult females always
return to the beach of their own birth to lay, in turn, eggs for the next
generation. The
nesting beaches for most green sea turtles are located in the
Northwestern Hawaiian Islands. The
females sometimes migrate as far as 800 miles, in order to
reach their natal beach. The males usually
accompany the females that they later mate
with. Matting season usually occurs
in the spring and as often as five times every fifteen days. When the female turtle is ready to release her eggs, she
waits until night to nest. When
night comes she slowly progresses onto land, and then when on the sand uses her hind
flippers to make a hole in which to deposit her eggs.
Threats
There are five factors affecting the green sea turtle population.
One is hunting; green sea turtles are hunted for their shells, meat, and eggs.
The second is fisheries--when swimming in the sea the green sea turtles
can get caught in fishnets and drown. The third factor
affecting their population is coastal development, which degrades the habitats of these turtles by disrupting
the nesting areas. Another factor affecting green sea turtles is marine debris, mainly
plastics. The problem plastic
presents to the green sea turtles is that they may eat it and eventually die because of
it. The fifth and last factor
affecting green sea turtles is a disease called fibropapilloma. The fibropapilloma disease is a form of tumor that grows on
the soft tissue of the turtle and which ultimately kills it.
Some of the protective measures that have been established to protect
the green sea turtles are federal and state laws, which prohibit hunting, injuring,
or capturing them. Furthermore,
a recovery team in Hawaii has been set with the ultimate goal of
restoring
the species' population to its previous levels. Other laws
make buying or selling of sea turtle products illegal in the United States.
Overall, these protective measures will hopefully keep the green sea
turtle from becoming extinct.
Humpback
Whale
Curious Facts
The typical adult can
range in size from 35 to 48 feet long. Their scientific name is derived from their flippers,
Megaptera noveangliae, meaning giant wings.
In Hawaii, this graceful and peaceful animal is called Kohola.
The Kohola is not a native species to the Hawaiian Islands; instead they
are found all over the world. Nevertheless, the Kohola is considered a Hawaiian species because of
its annual trips to Hawaii.
The
Humpback whale belong to the suborder of Baleen whales or mysticetes because of
their feeding methods. Instead of
teeth these whales have baleen plates, known as whalebone.
The baleen plates are made of keratin, the same substance found in human
hair and nails. The feeding method
consists of opening their mouths and filling it with water; then they close the baleen plates and
expel the water.
A curtain of hair surrounding the plate’s inner edge then traps the
food. Then a rasping tongue
collects the food from the hairs. The
diet is made up of small fish, mackerels, and tiny shrimp-like organisms. The
blowhole for the Humpback or baleen whale has two openings.
When the air is expelled, a misty cloud of condensation appears above the
ocean's surface and horizon. .
Named
after their high, arched backs, the humpback whale can exhibit various acrobatic
leaps. One of the acrobatic leaps
is called breaching; when the humpback whale breaches it lifts its body about
two-thirds out of the water while simultaneously twisting. It is believed that whales breach because they are indulging
in a playful activity or because they are courting female whales.
An aggressive behavior is called head lunging.
Most of the time whales resort to head lunging to warn off
competitors. Curiously, whales can
also "sing." Scientists believe that only the male humpback
can sing, and his songs
change within a given area and season. Finally,
the most interesting of all behaviors is the pods that whales form.
Most pods represent a social group of whales with two or three members, although
larger pods have been documented.
Reproduction
Most pod relations are short-lived, with the exception being that between mother
and baby whale. The
cow-calf pod association occurs between a mother whale and her calf.
These pods usually last for a year, in which the mother whale nurses her
young. The cow-calf pod is one of
the most important because of the young whale's great need for attention and
care. During this period of five to
seven months the baby whale can attain a weight of a ton and a length of 27
feet. The calf is born eleven to
twelve months after its mother's routinely winter migration to warmer waters
in Hawaii. After becoming an
adult, the whale can live an average life span of 30 to 40 years.
Threats
Although
the humpback whale is a resilient animal, there are many factors affecting its population. One of the most
serious factors is whaling.
Commercial whalers kill whales for their oil, meat and whalebone. The
slaughter was immense in the nineteenth century; but today Hawaiians try to
maintain a policy of eco-tourism that makes preserving whales profitable.
Driftnets pose a serious problem for humpback whales because they can become
entangle din them; consequent, since 1993, driftnets have been rigorously regulated in Hawaii.
Marine pollution not only poses a threat to humpback whales, but all
marine life. Ocean dumping and
coastal runoffs take a toll on the oceans' delicate life balance.
Most of the oceans pollutants originate form the land, like
eutrophication and polychlorinated biphenyl (PCB).
These and other pollutants heavily stress the whale population.
Bibliography
for Polynesian Aquatic Animals
Johnson,
Brian W. The Hawaiian monks seal
on Laysan Island: (prepared by the U.S. Marine Mammal Commission).
Springfield, VA: The Commission; National Technical Information Service, 1981.
Ackerman,
Diana. Monk seal Hideaway. New
York: Crown Publisher, 1995.
Nolan, Ron S. Shark
control and the Hawaiian monk seal.
Springfield, VA: The Commission; National Technical Information Service,
1981.
Waters, John F.
Green turtles mysteries. New
York: Crowell, 1972.
Hirth,
Harold F.
Synopsis of the
biological data on the green sea turtle chelonia mydas. Washington D.C.: fish and Wildlife Service, U.S. Dept. of the
Interior, 1991.
Winn, Lois K. and Winn, Howard E. Wings In the sea: the humpack whale. Hanover [NH]: University Press of New England, 1985.
Nakamura,
Tsuneu. Gentle giant: at sea
with the humpback whale. San
Francisco, CA: Chronicle books, 1988.
Polynesian Flora & Fauna on the Web
General:
http://leahi.kcc.hawaii.edu/~et/wlcurric/
This site provides information (classification name, reproduction habits, endangered-species status, and interesting facts) on some of Hawaii’s aquatic animals such as the humpback whale, the Hawaiian monk seal, the green sea turtle, and dolphins.
This site focuses on Hawaii’s land species. You will be able to find information about yellow-faced bees, the hoary bats, koa/warrior tree, and other creatures. The site also offers information about Hawaii’s natural history, extinction issues, and alien species.
http://www.angelfire.com/h:/ecosystem/
In this site you will find
information about the Kodau Bog Fence Project.
The project is run by the U.S. Army’s natural resources staff in Oahu.
They are monitoring the rare plants and animals present in Hawaii, with
the hope of preserving them for future.
The Hawaiian Monk Seal:
http://leahi.kcc.hawaii.edu/~et/wlcurric/seals.html
http://ourworld.compuserve.com/homepage/jaap/monkksseal.htm#hawaiian/
The Green Sea Turtle:
http://leahi.kcc.hawaii.edu/~et/wlcurric/greenseaturtle.html
http://www.seaturtles.org.
http://www.turtles.org/
The Humpback Whale:
http://leahi.kcc.hawaii.edu/~et/wlcurric/whales.html
http://www.pacificwhales.com/
http://www.hwrf.org/
http://www.jasonproject.org/expenditions/whales2001/