Friday, February 15, 2013

Science Week 19: Finfoots and Kelp Dwellers

Australian Fur Seal There are many species of seals named for the fine fur that makes them so attractive to hunters. The large northern fur seal, found in chilly northern waters, was hunted to near extinction during the 19th century. These animals were protected by law in 1911, and populations later rebounded to 1.3 million animals.
There are eight species of southern fur seals, all smaller than their northern relative. They include the Guadalupe fur seal of Baja California, the South African fur seal, the South American fur seal, and the Australian fur seal.
Fur seals have sharp eyesight and keen hearing. They have small ears, unlike the earless or hair seals.
Although they breathe air, seals are most at home in the water and may stay at sea for weeks at a time eating fish, squid, birds, and tiny shrimp-like krill. Fur seals may swim by themselves or gather in small groups.
When breeding season arrives, however, these social animals gather on shore in very large numbers. Powerful males, known as bulls, establish territories and gather harems of up to 40 females, battling their rivals to establish dominance. During this season, coastlines are filled with roaring, growling, honking seals.
Female fur seals, or cows, give birth during this breeding season, then mate again just a few days later. The following year they will return to give birth to a single pup after a nearly yearlong pregnancy, and mate once again to continue the cycle.
Many fur seal populations have not rebounded from extensive hunting, and now face additional threats from climate change and overfishing, which can limit their prey. - National Geographic
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As with whales, dolphins, porpoises, and manatees from last week, seals are another water dwelling mammal.  The seals are altogether comfortable there, and wherever cool currents flow and small food animals abound, the finfoots will gracefully dive, leap, and play.
Even though the seal's feet have toes and nails, their wide webs resemble fins. The order of the seal family is Pinnipedia, meaning "fin-footed."  These mammals sometimes spend months of every year entirely in the water, but they also pull out on land and shuffle about. Some seals migrate, others feed along the same shorelines every season.

Senses
Sight: to be efficient underwater hunters, seals need to detect and catch prey. Since very little light penetrates at great depths, the eyes of seals are specially adapted to allow them to see underwater. The eyes are especially large – one of the endearing feature of pups – and the lens is structured to allow as much light in as possible. When on land, the eye is protected from bright sunlight by closing the pupil. Thus seals can see well both underwater and on land. Sight is probably more important on land than in the water, and anyone watching common seals will
notice that they raise their heads regularly to look for danger.
Hearing: the ears of the seals are also adapted to allow them to hear underwater as well as on land. The bones of the middle ear are larger than in land mammals, and there are changes in the shape and size of other bones in the skull. Sensitivity to sound helps them to detect prey underwater. It has been suggested that seals echo-locate, like whales and bats. Common seals are known to make clicks and trills underwater. It could be, however, that they are simply talking to each other.
Touch: when water is especially dark or murky, seals cannot use their excellent eyesight to help catch their prey. They have, however, sensitive whiskers called ‘vibrissae’ that grow on either side of the snout, above the eyes, and on top of the nose and are thought to detect vibrations in the water caused by moving prey. There are cases of blind seals surviving for a number of years in the wild, suggesting that for fishing the whiskers are more important than sight.
Smell: a sense of smell does not work in water for seals. If you watch a seal, you will see that it closes its nostrils tightly before diving, to prevent seawater from irritating the delicate membranes in the nose. But the nose-bones in the seal are large and quite complex, suggesting that a sense of smell is important on land. As soon as a pup is born, it and its mother sniff at each other. Not only do they recognise each other by their individual call, but by their individual smell. Basking seals often raise their heads and sniff at the air.

God's perfect design for the large brown eyes of the finfoot is to enable them to see equally well in air or in water. In the air, the pupil is slit-shaped horizontally. In the water, it expands to a round shape to take in more light. Seals have little to no duct on the inside of the head to drain away tears as most mammals do. For this reason, when they are out on shore and their fur is dry, they often appear to be crying.
Hair seals have ears that are only openings in the side of their head. When the seal dives, these ears are closed partly by water pressure and partly by the seal's own muscles. Their nostrils close, too. Since sound travels so much better in water than in air, the seals can still hear, just as whales can, while their ears are closed.
Whales have no vocal cords, yet they are able to call in quite audible voices (remember the whale song clips from last week?) Seals, however, have vocal cords, and they can yelp, whimper, yap, bark, and roar. Sounds that are not vocal are often heard from seal pods. As the noisy, chubby mammals lie dozing and basking, packed together, one will hear coughs, yawns, sneezes, and more. The common harbor seal also beeps high squeaks beyond what the human ear can hear. It could be echolocation to aid them in finding the fishes, shell fishes, and crabs they feed on.

Limbs and movement
A seal has much shorter limbs than most mammals: what appear to be the armpit and groin of a seal are, in fact, the equivalent of the wrist and the ankle. By comparison, the bones of their flippers are enormously long, and the skin between them forms a web which is used like a paddle to propel the seal along. They have long, sturdy claws on their front flippers which they use to help them move on land, especially when they need to grip onto rocks or ice.
When a seal swims quickly, it holds its front flippers tightly against its sides, and propels itself with its powerful hind flippers. Its lower body moves from side to side, rather like a fish, as it moves along. When the seal is swimming slowly, the front flippers are used as stabilisers and stick out to the sides.
On land, a seal moves with a ‘hitching’ action. It forces it weight onto its chest, and then stretches its back to swing its rear end forward. The weight is transferred to the pelvis, and the chest is thrown forward. It is an inefficient way to move, and has made them vulnerable to hunting by humans. On ice, however, the seals are far more limber. Ribbon seals and leopard seals, that live in the Arctic and the Antarctic respectively, can move faster than a human can run, by flailing their hind flippers vigorously.

God has also planned for the flippers so that they do not need to be as warm as the other parts of the bodies. Little heat is lost through the flippers. Fur covers the flippers of mammals in the hair seal family. The bones of the front limbs resemble the leg and toe bones of other mammals. The long ones are inside the body, and the five rows of small bones support a wide spreading flipper complete with five toenails. When the hair seal swims, these front limbs are tucked into hollows somewhat like the human armpit, unless the creature wants to steer or to turn. Once on shore, the hair seal's front flippers take over the main work of locomotion. The hind flippers cannot be turned forward. The finny fingers are curved, stiffened, and dug into the sandy ground as the wet, slippery creature wriggles along to a spot near its fellow seals.

Regulating body temperaturesHarp seals are very good at conserving their body heat. With a thick layer of blubber under their skin, harp seals are able to hold their body heat more easily. This layer of fat also provides a means of buoyancy, stores energy, and gives the seals a shape that is better suited for the aquatic environment where they are often found. In young harp seal pups you can find fur on the surface of their skin in order to keep their small bodies warm.Another interesting way that the seals keep warm has to do with the same redirect of blood flow that allows them to remain submerged longer. They lower their heart rate by 90%; supplying only the nervous system and sense organs with a normal flow of blood. By redirecting the circulation away from the surfaces, they are preventing a substantial amount of heat loss.     

Animal Corner, Seal Anatomy
Exploring Nature Seal page
General Seal Characteristics
Skin & MoltingHarp seals are well known for having a fuzzy white coat as a pup. The fur of a pup is well adapted to the lifestyle of harp seals. There is a water repellant layer on the outside to help lessen resistance in water; however there is still a warm insulating layer underneath that to help with thermoregulation. It was for this very reason that the harp seals were almost hunted to extinction. Hunters found the fur of these creatures to be very valuable.  
Molting for harp seals happens once a year. During the molting period the seals get rid of their worn out skin and replace it with a new one. Most often during this time, harp seals remain on land; when replacing their skin there is a compromise to how well they can retain body heat. So as not to risk hypothermia, harp seals wait for their skin to be ready for the frigid waters of the arctic.
A Harp Seal's Life Cycle

Most mammals drop their hair and flakes of skin all year. This dead hair and skin would be uncomfortable when water soaked while swimming. Each year, seals molt and emerge with an entirely new set of skin and hair. Seals often stay near land while the days, or the weeks, of their molt last.

The Lifecycle of the Seal
Harbor Seal Fact tabs, Alaska Dept. of Fish and Game


The Elephant Seal, National Geographic site (has a great audio clip as well)
The Marine Mammal Center
Squidoo Lens on Seals

The Elephant seal, the largest finfoot of all, is a hair seal that can dive to great depths and may go down as deep as 2000 feet. The male has a trunk-like nose that develops after the male is 2 years old. It sometimes becomes long enough to overhand the mouth by as much as a foot when it is relaxed. The roar of the big elephant seal may be heard for several miles. Elephant seals eat their food without being chewed so their intestine is very long. It was noted that one elephant seal had an intestine tract 662 feet in length!
Each year in the late spring, cow and bull seals choose a stretch of beach and repel other cows and bulls trying to come ashore at that point. Seals do not appear to be sensitive to pain and will continue to fight despite deep wounds, even lost eyes. The fights can dye the surrounding beach and waters for miles, but one seal rarely kills another. Bulls do not leave the spot even to hunt for food. For 1-2 months, both cows and bulls bellow and battle.
Pups are born a week or more after a cow comes ashore, but many are crushed in the constant fights surrounding them. At birth, a pup weighs 80 lbs, is 4 ft. long, and is covered with black, wooly fur. During their first 3 weeks of being nursed, the pup may gain as much as 300 lbs, eating the rich, 4/5ths fat milk. The pups immediately lay in a blubber layer that will nourish them for as long as a month after their mothers leave them; however, many die that first year before learning how to feed themselves, as many as 50% of those who managed to survive the dangers of being born into fighting grounds.


image
photo credit: Exploring Nature

Walrus Mom video, National Geographic
National Geographic Walrus page
Defenders of Wildlife Walrus
Walrus printout  Enchanted Learning
ThinkQuest Walrus
Heart of Wisdom links
a great Pinterest board of Arctic studies, with crafts and ideas for this weeks study
Squidoo Lens on Ocean Life with usable bits
I Choose Joy! blog has a great post on the top ten Walrus study videos at YouTube.

The walrus...a bulky, almost hairless creature, with a hide that may be as much as 2 inches thick of lumpy and bumpy skin and up to 6 inches of blubber. A heavy mustache of about four hundred stiff, white bristles, droops from the huge nose, and from the upper jaw to protect two great tusks that may weigh as much as 12 lbs each, and reach a length of 3 1/2 feet in the male, and 2 feet in the female. No flaps protect the holes that are its ears.
The walrus feeds in shallow water, digging up mussels and clams from the bottom, sorting out the empty pieces with the bristles of the mustache. The shell fishes are taken into the mouth and ground apart with the short, sharp teeth. The meat is eaten, the shells spit back into the water to sink.
Most scientists recognize two subspecies of walruses: Odobenus rosmarus rosmarus (Atlantic) and Odobenus rosmarus divergens(Pacific). Odobenus comes from the Greek: "tooth walker", and refers to the walruses' method of pulling themselves up onto the ice with their long tusks.
The scientific name of the walrus means "he who walks with his teeth" and it does pull itself up onto the edges of ice floes with its tusks. It can turn its flippers forward to travel more easily on land than the hair seals. These sociable creatures like to be close to each other, and latecomers to the ice floe have no choice but to begin another layer. Sometimes the floe is overloaded at one side and will tip, dumping the whole herd back into the frigid water.
Unlike the hair seal, the walrus sleeps in the water, in an upright position. Alongside the neck are pouches the walrus can inflate at will. These hold as much as a cubic foot of air. Possibly they hold the head out of the water while the mammal slumbers.



The Encyclopedia of Earth, eared seal page
Animal Planet
SeaWorld Lesson Plans, Seals, Sea Lions, and Walrus' PDF

Another finfoot is the eared, or true, seal. They number 12 species, and like the walrus, they have massive forequarters. They swim by paddling of the front flippers. The flippers are naked, usually of black skin, with arm and leg bones projecting from the body in addition to the hand and foot bones.  The rear flippers can be turned forward to support the weight of the body. The eared seals have shuffling walk and even a clumsy gallop about as fast as a man can run.
Worldwide there are 5 species of sea lion. They sport short, pointed ear flaps, the huge neck and shoulders, and the naked flippers of the eared seals. The California Sea Lion is commonly found in zoos, where it is easily tamed and taught several tricks.

The Marine Mammal Center, Sea Lions
San Diego Zoo Animal Bytes
National Geographic 

Baby Sea Lion Swim lesson


California sea lions are faster than any other seal or sea lion. They can swim at
speeds up to 25 miles per hour. They can also make deep dives, staying under
water for up to 10 minutes pursuing fish, squid and shellfish.
Size  Males can weigh up to 1,000 pounds and grow up to 8 feet long.
Females tend to be significantly smaller, weighing up to 400 pounds and
growing up to 6.5 feet long.
Diet  A variety of fish, including Pacific whiting, market squid,
shellfish, rockfish, herring and salmon
Lifespan  18 to 25 years
Range  Eastern North Pacific Ocean from the Gulf of Alaska to Baja California
Habitat  California sea lions are generally found in waters over continental shelf
and slope zones; they frequent coastal areas, including bays, rivers and harbor mouths.
Predators  Sea lions are hunted by orcas and large sharks; pups are hunted by
coyotes and feral dogs on land.
Relatives  Sea lions and Northern fur seals are in the same family known as "eared seals."
They are known for their ability to rotate their flippers under them and "walk" on land.
Family life  California sea lions do not form pair bonds; one male will breed with many females.
After an 11-month gestation period, the female gives birth to a single pup. Pups weigh 13 to 20
pounds at birth; they are usually weaned after 12 months.

Photo: A New Zealand fur seal and her pup lounge on a rock

In the fur seal family there are 8 species, living off the coasts of all the continents of the world except Europe. the northern or Alaskan fur seal lives along the eastern and western coasts of the North Pacific. These seals have very thick, fine fur that traps air and insulates them against the cold. Fur seals molt by shedding their hairs singly, though not all the hair is shed. Through the years to coat becomes thicker.
Every September the females and young move down the Pacific coast, swimming up to 50 miles offshore, and going as far south as California, returning to their home by June. Fur seals find it easy to become too warm out on land in the summer. They lose heat by panting and by sweating through the many sweat glands of the flippers. Sometimes they wave their black, naked fins like fans.

Photo: Sea otter with head and paws visible above the water

Kit the Sea Otter 

Exploring Nature, Sea Otters

The sea otter, belonging to the weasel family, spends more time in the water than seals do. This creature, of the Carnivora order, eats all kinds of shell fish and other sea animals. It has the most beautiful and valuable fur in the world, with one skin bringing as much as $10,000 in the early 1900s. There are as many as 650,000 single hairs in each square inch of the pelt!
Sea otters nearly always swim on their backs, with their heads up. When the sunshine glares they shade their eyes with their paws. Shell fish, when brought up from the depths, are held and cracked open on a rock resting on their stomach. The young otter is held on the stomach, too, and fed from the milk glands. They live out from the Pacific coast in kelp beds within a mile from shore. The young are born here, and the adults sleep with strands of the kelp wrapped around themselves to prevent their drifting out into open water.

God's Amazing Sea Creatures unit, Homeschool Helper Online
lapbook, Maria's Comet, HomeschoolShare loosely tied to the mammals of the sea weeks
Squidoo Lens on marine biology topics, some good reading for these weekly studies

These mammals have all experienced the fate of the whales over the years. The walrus has always been used by Eskimos without reducing the population. Hides, tools, rope, fuel oil, and ivory were products gained from the walrus. When whales became scarce, the whalers began hunting walruses for oil until they could no longer be found in numbers large enough to be profitable. Since 1960, walrus cows and calves have been protected.
The elephant seal, being large, yielded much oil. California sea lions were also taken in great numbers for oil. The northern fur seals and the sea otter were nearly wiped out for their valuable fur. The international treaty of 1911 brought the killing to a halt, and 22 years later, a single herd of elephant seals numbering less than 100 was found.
After the treaty of 1911, no sea otters were known of, yet, in 1938 a few were discovered in a very craggy spot where hunters had failed to find the last specimens. Today they are completely protected as well.
In the treaty of 1911, nations agreed to kill only the fur seals, and only on land, where they could distinguish the cows from the bulls. The beautiful fur is now harvested annually, some 60,000 skins from bulls only. The Alaskan herd numbers 2 million.











Monday, February 11, 2013

Science Week 18: Mammals of the Seas



Yet again, Blogger ate my draft awaiting publishing. I guess I just need to get into a schedule where I can sit at the computer weekly and not store posts to set into place at later dates.
Even the sea monsters draw out the breast, they give suck to their young ones...Lamentations 4:3
Jeremiah, a prophet of old Israel, knew about the order of mammals that spends its whole life in water.  He called it the sea monsters and noticed the tender feeding of the young on milk.

List of Cetaceas, Wikipedia


To get you started:
Whale Lapbook, Homeschool Share
Whale Lapbook components, Lapbook Lessons

The order Cetacea contains 90 species of whales, dolphins, and porpoises. Since cetaceas only live in water and have long, streamlined bodies, some people mistake them for fish. How do we know they are mammals?
(Mammals are warm-blooded vertebrates that have hair, usually bring forth their young alive, and nourish them with milk).
Many adults have whiskers and some young have soft hairs early in life, or before birth. All cetaceas bear their single young alive and nourish it with milk. Whales, porpoises, and dolphins have powerful flukes that spread horizontally, unlike the vertical tails of fishes. As other mammals do, they breath air through lungs.  Most mammals have 2 pairs of limbs, but cetaceas have only a single pair. the manatee is another mammal without a rear pair of limbs.


The cetaceans most important sense is hearing, with sight a close second. Just as bats in total darkness find their way with echolocation (remember week 12/bats?), so do cetaceans. God has so delicately constructed these almost unbelievable hearing organs that the dolphins can sort out all the echoes of his own cries from dozens of other signals raised by other citizens of the sea, By these sounds the size, shape, and speed, distance away, and direction of the movements of other creatures are understood as well as the outlines of the sea bottoms, and other physical features.

Song of the Whale


Kingdom of the Blue Whale

PBS: Realm of the Killer Whales

Cetaceans are divided into 2 main groups. The toothed whales have a single blowhole and flippers with four rows of bones. The toothless whales breathe through a double blowhhole and have flippers with five rows of bones. Toothless whales have hundreds of thin, flexible bones called baleen in their mouths. Fine mesh hangs from the inner surfaces of each one. The baleen whales do not swim below 325 feet. They feed on young shrimps, snails, sea jellies, lobsters, sponges, crabs, fishes, sea stars, and various one-celled creatures. these are called plankton or krill. 
In former times, whale baleen was used in making umbrella ribs, fishing rods, and buggy whips. In 1897 whalebone, or baleen, sold for $5000 a ton. Metal and plastics are used for these purposes now. 

Photo displaying dozens of baleen plates. The plates face each other, and are evenly spaced at approximately 0.25 inches (1 cm) intervals. The plates are attached to the jaw at the top, and have hairs at the bottom end.
Baleen is a filter-feeder system inside the mouths of baleen whales. The baleen system works when a whale opens its mouth underwater and then water pours into the whale's mouth. The whale then pushes the water out, and animals such as krill are filtered by the baleen and remain as food source for the whale. Baleen is similar to bristles and is made of keratin, the same substance found in human fingernails and hair. Some whales, such as the bowhead whale, have longer baleen than others. Other whales, such as the gray whale, only use one side of their baleen. These baleen bristles are arranged in plates across the upper jaw of the whale. Baleen is often called whalebone, but that name also can refer to the normal bones of whales, which have often been used as a material, especially as a cheaper substitute for ivory in carving.

photo and Where Whales Live text via WhaleFacts.org
So where do whales live?
  • Killer Whale – The killer whale can be seen traveling throughout the worlds major oceans, but they typically prefer cooler climates compared to the tropical climates found near the equator. As stated earlier the migration pattern of these whales is more often than not determined by their prey’s migration.
  • Gray Whale – Gray whales are often found swimming in the eastern and western north pacific ocean during feeding season and will migrate towards the Baja peninsula of mexico and the southern golf of california where they mate and bare off spring during their mating period.
  • Humpback Whale – While humpback whales can be found traveling all over the world they prefer the cold waters in and around the Arctic and Antarctic oceans.
  • Blue Whale - Blue whales (like humpback whales) can also be found traveling all the major oceans. They can often be seen swimming in the colder regions during feeding season and will migrate towards tropical waters when mating.
  • Bowhead Whale – Unlike other species of whale bowhead whales are generally found traveling in Arctic/sub Arctic oceans year round and aren’t known for making long migration trips.
  • Minke Whale - There are two known species of minke whales currently in existence, the common or north Atlantic minke whale (which inhibits the north Atlantic waters) and the Antarctic or southern minke whale (which lives in the Antarctic region south of the equator). Due to differences in climate changes in both regions the two species of whale do not meet one another during mating periods because their mating seasons are different.
  • Sperm Whale - Sperm whales can be found in all of the worlds major oceans. Female sperm whales and their young prefer to stay in near tropical waters all year-long while the males can be seen traveling back and forth from the colder climates to the warmer climates during mating periods.
  • Beluga Whale – Beluga whales are generally found swimming in shallow coastal water in and around Arctic waters. Depending on the area and environment the whale is in some beluga whales will make seasonal migration trips while others will only travel within a small localized area.
  • Narwhal Whale – Narwhal whales can be found living in or near the Canadian Arctic and Greenlandic waters throughout the year. During the fall and winter they migrate away from the coastal waters (off shore) in order to avoid large areas of ice and frozen water and will move back towards coastal grounds during the warmer spring and summer months.
Largest Blue Whale Colony, Sri Lanka

The whale's blowholes have powerful valves. As it comes to the surface, the hole opens. A volume of compressed air rises perhaps 20 feet, taking along any water that happens to be over the blowhole. A deep breath rushes into the lungs and in 2-3 minutes is absorbed by the blood. The whale blows again and refills its lungs. Finally, after a number of blows, the whale is fully recovered and ready for another long breath-holding dive.  Oxygen enters even the muscles. The lungs are folded flat. The whale jack-knifes, then as it goes down, raises its flukes from the water in a backward kick that sends it to the bottom. The heartbeat slows to about 1/3 of its usual rate. In the cold, blood leaves the skin, flippers, and flukes to enter the heart and brain. The body temperature drops. Many whales have heating systems that keep them warm in icy seas. This system overheats when the mammal is stranded on the beach. Without the support of the ocean currents, the heavy blubber on a whale's body will prevent its lungs from filling up. A large cetacean will suffocate under its own weight when it is not in the water.

Whaling History Notes:
History 1800s Whaling, About.com
A Right Whale study, 5 lessons from Wheelock
....Metompkin and Her Story online here
Herman Melville's Moby Dick free online
ThinkQuest Whaling page


Properties of Underwater Accoustics
Whalesong.net with live streaming
Humpback whale songs, Ocean Mammals Institute
NOAA Fisheries, Dept.of Protected Resources has some nice lesson plans on whales for teachers and students
Enchanted Learning, Whales
Defenders of Wildlife, Whales
UCMP Berkley, Intro to Whales
Whale behavior, Whale Trust
Great (Baleen) Whales also check out links at end of article
Whale Facts, About.com, such as...
..........Whales rest one-half of their brain at a time when they sleep.
The way whales "sleep" may sound strange to us, but makes sense when you think of it like this: whales cannot breathe underwater, which means they need to be awake just about all the time in order to come up to the surface when they need to breathe. So, whales "sleep" by resting one half of their brain at a time. While one half of the brain stays awake to make sure the whale breathes and alerts the whale to any danger in its environment, the other half of the brain sleeps.
                                 
bottle-nosed dolphin

Dolphin lapbook from HomeschoolShare
Island of the Blue Dolphins lapbook, Notebooking Nook
   full length movie here on YouTube
Dolphin Facts, About.com Marine Life

The smaller toothed whales, called dolphins, having been kept in captivity, have learned to mimic the sounds of human conversation as many parrots and myna birds do. In captivity, they can successfully be trained to do various sea-faring tasks, as evidenced by Morgan, a pilot whale trained by the U.S. Navy.
Porpoises live on the northern Atlantic coast, and on the Pacific coast south to California. They feed mainly on fish which they gobble without much chewing. They remain underwater only a few minutes at a time. Dolphin and porpoise spouts are not visible.

Mother Whale and Calf

A great whale's milk glands can squirt milk up to a distance of 6 feet. Located in two folds of skin, they deliver a rich milk that is more than 1/3 fat. The cow usually turns on her side so the calf can drink with its blowhole out of the water. The calf adds about 230 lbs a day, gaining a ton every 9 days. Their rate of growth slows as they mature. They will continue nursing for 9 months. They may be 8 years old before they themselves can become parents.
This slow reproduction rate makes it impossible for the whales to multiply as fast as they are being hunted and killed.  Speedy catcher ships equipped with bomb-carrying harpoons shot from cannons, and with underwater detecting devices, fan out from modern factory vessels that completely process a whale's body in less than an hour. Along with widely cruising spotter planes, these outfits regularly visit the whale's feeding grounds in the Atlantic and Arctic. Since 1925, 2 million whales have been slaughtered and changed into oil, meat, and fertilizer. At present, it is estimated that we lose 50 thousand whales every year.
No product made of the body of a whale can be legally brought into the United States thanks to the Marine Mammal Protection Act, passed in 1972. Fifty-six other countries have agreed to protect completely tghe blue, the humpback, the right, the gray, and the bowhead whales. Only native peoples are not covered by this law.
New Bedford Whaling Museum, Whaling History 1861-1987

Access the Jacques-Yves Cousteau channel on YouTube here.

David Schrichte manatee photo

The manatee, also called the sea cow, is a tropical vegetation-eating water mammal. Like whales, it has no hind limbs and swims by up and down motions of its horizontal, very round, flukes. A full-grown manatee may eat as much as 100 lbs of water plants daily, scooping them into a big-lipped mouth with its flippers. Manatees feed with their head and shoulders out of the water. They drift slowly about the warm bays and lagoons of southern Florida. They live mostly in the protected sanctuary of the Everglades National Park, which will help allow the species to continue.
The milk glands of the manatee are on its chest, and the mother floats upright in the water, clasping her single young one with her flippers while it nurses. As the mother manatee grazes on water plants, the father holds the calf in his flippers. The manatee infant is cradled in the flippers of either parent for some weeks after birth. Nearly 2 years pass before the young is left to make its own way.

Manatee, A Gentle Giant

Save the Manatee Club...listen to their calls here...see diagrams of their anatomy here...a manatee book list here...Save the Manatee coloring book PDF...


Did You Know?Manatees only have molars, which are used to grind food. As they wear down and fall out, they are replaced with new teeth.Manatees only breathe through their nostrils, since while they are underwater their mouths are occupied with eating! A manatee's lungs are 2/3 the length of its body.

Friday, February 1, 2013

Science Week 17: Great Bears of the Forest and Ice Floes

Except for opossum babies, no other mammal infants are as tiny in comparison to their mother as the bear infants. Born during the mother's winter hibernation, they may weigh as little as 1/200th of her weight. In the dark, cold den, the small rat-sized cubs are nearly lost in the dense fur of their mother. Hairless and blind, they snuggle contentedly into the shaggy folds of the mothers abdomen, where hidden milk glands allow for warm, comfortable nursing.

photo credit: Drive to Nature blog

Bears are mostly created for forest and mountain regions. In the spring bears graze like cattle on the new tender shoots and grasses. Later in the season, they use their strong shoulders, and powerful claws, to rip open rotting logs to lick up ants, beetle grubs, termites, and many other insects. Digging into ground burrows, they find chipmunks, marmots, moles, mice, ground squirrels, and lemmings. Crickets, grasshoppers, birds and their legs, snakes, frogs and toads, acorns, fruits, and wild honey, keep these big mammals well nourished.

Black Bear
photo credit: Bears of The World

The black bear is the smallest and most common of the American bears, and like other bears, it travels alone except for when still being cared for by its mother as a young cub. The same trails through forests and thickets will be followed for 50 years or more. Along these trails, bears will stand on their hind legs and rub their backs against the bark of trees. They bite it until it shreds loose in places, where pitch oozes out and sticks their hair to the trees. The next bear on the trail will do the same thing, leaving his scent behind for the next trail walker.


Grizzly Bear

Next in size to the widespread black bear is the grizzly. Originally found in the western part of North America, from Alaska to central Mexico, and east to Minnesota, there are now very few south of the Canadian border except in protected wildlife park areas.


The grizzly's diet is roughly 80-90% vegetation, though they come down to meet the salmon that run up-river from the sea. As the salmon swim up-river, the bear will knock it out of the water with a blow from its paw. When injured or attacked, the grizzly will react fearlessly.  It can run as fast as a horse, and a blow from its paw will crush or break the bones of even a huge bison.

Grizzly Bears, Bears of the World

File:Bear Square.JPG
photo credit: Wikipedia

The brown bear, also known as The Alaskan Brown Bear or Kodiak Bear is the largest of all bear species. Like the grizzly, it has its own set of trails along the rivers of British Columbia and southern Alaska. As the salmon swim up the river by the thousands, the big brown bears have a feast. After spawning, the salmon die and float down-stream, sooner or later coming to rest against a rock or sandbar. The great bears enjoy eating carrion, so the smelly dead heaps of fish are quickly removed and the riversides become clean in short order.

Brown Bears, Bears of the World
Brown bears, Alaska Dept. of Fish & Game be sure to check all the tabs below the article for more information

Brown bears are larger than black bears with male grizzly bears standing about 7 feet tall and generally weighing from 200 to 600 pounds. There have been some male bears that have weighed more than 800 pounds. Females are smaller, usually weighing between 200 and 400 pounds. Generally remaining on all fours, when a grizzly does stand, it is commonly perceived to be a threatening pose however they are just simply curious or surveying their surroundings.
Despite being categorized as ‘black bears' and ‘brown bears' to make a distinction, color is never an indicator of species. Both black and brown bears can range from almost white to blonde to pure black and many color phases in between depending on age, sex and season.
The main differences between the black bear and brown bear, is that the brown bear has a rather concave face, high-humped shoulders, and long, curved claws. The grizzly's thick fur, which varies from light brown to nearly black, sometimes looks frosty-looking, hence the name "grizzly," or the less common "silvertip."
Furthermore, the grizzly has more rounded shorter ears. Nevertheless, you cannot pin point one characteristic to distinguish between a grizzly and black bear, it is a combination of characteristics that will help you identify the bear specifically. Each may have a similar-colored coat, a less-than-concave face and small or large shoulder humps.
~~via Brown bear.org




File:Polar Bear - Alaska.jpg
photo credit: Wikipedia

The polar bear is the monarch of the arctic ice pack. On snow covered floes, these great bears will drift for hundreds of miles in the Arctic ocean, the Atlantic ocean, or through the Bering Strait into the Bearing Sea. They may swim 15-20 miles out to an iceberg in search of their most important food source, seals. When the seals are scarce, they will live on carrion. A sudden freeze may strand a white whale or a narwhal inside a little bay that later becomes so small the creature cannot breath adequately. A polar bear may kill even a whale that is 15 feet long. The powerful carnivore is able to drag an 800-pound animal out onto the ice. A large dead whale will provide food for bears, arctic foxes, gulls, and ravens all winter.
Fast Facts
  • Size
  • Males: 600–1200 lbs. 8–10 ft.; Females: 400–700 lbs.
  • Lifespan
  • 25 years
  • Distribution/Range
  • Circumpolar, northern hemisphere only
  • Diet
  • Ringed seals, bearded seals, walruses, beluga whales
  • Predators
  • Male polar bears, and Alaska Native hunters
  • Reproduction
  • 2 cubs once every 3 years


Bears lapbook, Homeschool Share, another one here, heared toward Preschool-1st
Polar Animals lapbook, Homeschool Share
Polar Bear Squidoo Lens
Polar Bear lapbook at The Schroeder Page blog
Polar Bears, Early and Modern at Bears of The World

Bears like to clown around and play like most animals. A polar bear will rock themselves on a drifting ice floe or slide down a slanting, slippery glacier side. They have been seen walking along a narrow wall of ice with an almost vertical glacier below, then jump onto the slick surface of the glacier and whiz itself down, without trying to slow themselves down, until they reach the edge of the glacier. There, with a sheer 50 ft drop, they will sail into the air and plunge into the water below. Sometimes they will sit near an icy slope and, just as you or I would, rock themselves back and forth to get started sliding downward. 

bear track account, Wilderness College