My Science School

The narwhal is the unicorn of the sea, a pale-colored porpoise found in Arctic coastal waters and rivers. These legendary animals have two teeth. In males, the more prominent tooth grows into a swordlike, spiral tusk up to 10 feet long. The ivory tusk tooth grows right through the narwhal's upper lip. Scientists are not certain of the tusk's purpose, but some believe it is prominent in mating rituals, perhaps used to impress females or to battle rival suitors. Females sometimes grow a small tusk of their own, but it does not become as prominent as the male's.

Narwhals are related to bottlenose dolphins, belugas, harbor porpoises, and orcas. Like some other porpoises, they travel in groups and feed on fish, shrimp, squid, and other aquatic fare. They are often sighted swimming in groups of 15 to 20, but gatherings of hundreds—or even several thousands—of narwhals have been reported. Sometimes these groups become trapped by shifting pack ice and fall victim to Inuit hunters, polar bears, or walruses.

Inuit people hunt the narwhal for their long tusks and their skin, an important source of vitamin C in the traditional Arctic diet.

Credit : National Geographic 

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Humpback whales are found in every ocean in the world. Their Latin name, Megaptera novaeangliae, means "big wing of New England." It refers to their giant pectoral fins, which can grow up to 16 feet long, and their appearance off the coast of New England, where European whalers first encountered them. They have dark backs, light bellies, pleats on their throats, and a small hump in front of their dorsal fins, leading to the common name of "humpback."

Humpback whales are known for their magical songs, which travel for great distances through the world's oceans. These sequences of moans, howls, cries, and other noises are quite complex and often continue for hours on end. Scientists are studying these sounds to decipher their meaning. It is most likely that humpbacks sing to communicate with others and to attract potential mates. Humpback calves are known to "whisper" to their mothers.

These baleen whales are found near coastlines, feeding on tiny shrimp-like krill, plankton, and small fish. Humpbacks migrate annually from summer feeding grounds near the poles to warmer winter breeding waters closer to the Equator. Mothers and their young swim close together, often touching one another with their flippers with what appear to be gestures of affection. Females nurse their calves for almost a year, though it takes far longer than that for a humpback whale to reach full adulthood. Calves do not stop growing until they are 10 years old.

Humpbacks are powerful swimmers, and they use their massive tail fins, called flukes, to propel themselves through the water and sometimes completely out of it. These whales, like others, regularly leap from the water, landing with a tremendous splash. Scientists aren't sure if this breaching behavior serves some purpose, such as cleaning pests from the whale's skin, or whether whales simply do it for fun.

Credit : National Geographic 

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Gray whales have a hump and a ridge of sharp bumps along their backs, instead of a dorsal fin. They are a type of baleen whale, which means they filter food from the water through special bristly structures in their mouths. Gray whales stay close to shore and feed in shallow water. Their well-known migrations take them between feeding and breeding areas, swimming as much as 12,000 miles round trip.

Critically endangered western gray whales migrate into their summer feeding grounds near Sahkalin Island, Russia in late May or early June and return to their winter feeding grounds in the South China Sea in late autumn. Summer feeding grounds for the eastern population lie in the Bering and Chukchi Seas between Alaska and Russia. In the winter, these eastern gray whales migrate south along the west coast of the US to Mexico to breed and have their calves.

The calm, warm waters of the lagoons are a safe place for young whales, free from predators like killer whales. Locals here affectionately call gray whales "friendly ones" as they have an unusual tendency to approach whale-watching boats and check out the occupants.

Credit : WWF

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The blue whale is the largest animal on the planet, weighing as much as 200 tons (approximately 33 elephants). The blue whale has a heart the size of a Volkswagen Beetle. Its stomach can hold one ton of krill and it needs to eat about four tons of krill each day. They are the loudest animals on Earth and are even louder than a jet engine. Their calls reach 188 decibels, while a jet reaches 140 decibels. Their low frequency whistle can be heard for hundreds of miles and is probably used to attract other blue whales.

Whales are at the top of the food chain and have an important role in the overall health of the marine environment. During the 20th century, the blue whale was an important whaling target and even after it was protected and commercial whaling stopped in 1966, exploitation efforts by the former Soviet Union persisted.

Blue whales live in all the world's oceans, except the Arctic, occasionally swimming in small groups but usually alone or in pairs. They often spend summers feeding in polar waters and undertake lengthy migrations towards the Equator as winter arrives.

These graceful swimmers cruise the ocean at more than five miles an hour, but accelerate to more than 20 miles an hour when they are agitated. Blue whales are among the loudest animals on the planet. They emit a series of pulses, groans, and moans, and it’s thought that, in good conditions, blue whales can hear each other up to 1,000 miles away. Scientists think they use these vocalizations not only to communicate, but, along with their excellent hearing, to sonar-navigate the lightless ocean depths.

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Belugas are extremely sociable mammals that live, hunt and migrate together in pods, ranging from a few individuals to hundreds of whales. Their bulbous forehead, called a "melon”, is flexible and capable of changing shape. This allows them to make different facial expressions. Belugas can produce a series of chirps, clicks, whistles and squeals, which give the beluga its other name, "the canary of the sea." They may sound like music or even nonsense to us, but to fellow belugas they convey important information.

Many populations of belugas migrate as the sea ice changes in the Arctic. They move south in the fall as the ice forms and then return to feed again in the spring, as the ice breaks up. They can also be found near river mouths, and sometimes even venture up river. Belugas feed on a variety of fish species, such as salmon and herring, as well as shrimp, crabs and mollusks.

Whales, like the beluga, are at the top of the food chain and have an important role in the overall health of the marine environment. Beluga whales are also culturally important to indigenous communities in the Arctic. Like polar bears, the beluga depends on sea ice for its existence and can be directly impacted by climate change.

Credit : WWF

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Olive ridley turtle is a species of turtle that live globally in the coastal waters of at least 80 countries. It is named for the generally greenish colour of its skin and shell, or carapace.

It is among the smallest of the sea turtles, reaching only about 2 feet in shell length. It feeds on jellyfish, snails, crabs, and shrimp and occasionally algae and seaweed.

Females migrate hundreds or even thousands of miles every year to lay eggs on tropical and subtropical beaches. They lay about a hundred eggs, but may nest up to three times a year.

These turtles are solitary, preferring the open ocean. They migrate hundreds or even thousands of miles every year, and come together as a group only once a year for the arribada, when females return to the beaches where they hatched and lumber onshore, sometimes in the thousands, to nest.

Olive ridleys have nesting sites all over the world, on tropical and subtropical beaches. During nesting, they use the wind and the tide to help them reach the beach. Females lay about a hundred eggs, but may nest up to three times a year. The nesting season is from June to December.

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When danger threatens, the squid, like the octopus and the cuttlefish, can squirt dark ink fluid to conceal themselves. The ink clouds the water and confuses their enemy.

Squid are aggressive hunters, but some species are worse than others. The Humboldt squid is of particular danger to divers because it's large -- about the size of a man -- and shows little fear or hesitation when hunting prey. Colossal squid are just as aggressive and fast hunters, and they top out at 2,000 pounds. Thankfully, these giant sea creatures tend to stay in deeper water away from where humans typically dive.

When trying to avoid squid, divers might look for the telltale oblong shape and colors such as red or white. What makes squid dangerous is that their colors aren't constant. They have the ability to change color almost instantaneously to match their environment. If you spot a squid while diving, you could lose sight of him quickly as he morphs to blend in with the background. He can hit you from what seems like out of nowhere.

Many squid have more than suction cups on their tentacles -- they have sharp teeth or claws to grab prey. When a Humboldt squid grabs a diver, for example, he engages teeth that ring each suction cup. Each squid can have up to 35,000 teeth. These sharp teeth bite through protective swim gear to grasp and tear flesh. Squid with claws can rip and tear through your suit and skin. Squid also have sharp beaks designed to pierce the hard flesh and exoskeletons of sea creatures; your skin isn't a match for this strong mouthpiece.

Credit : Pets on Mom

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It sounds like a galleon but it is really a very dangerous type of jellyfish! Its poisonous stinging tentacles up to 25 m (82ft) long can sometimes kill humans.

The man-of-war comprises four separate polyps. It gets its name from the uppermost polyp, a gas-filled bladder, or pneumatophore, which sits above the water and somewhat resembles an old warship at full sail. Man-of-wars are also known as bluebottles for the purple-blue color of their pneumatophores.

The tentacles are the man-of-war's second organism. These long, thin tendrils can extend 165 feet in length below the surface, although 30 feet is more the average. They are covered in venom-filled nematocysts used to paralyze and kill fish and other small creatures. For humans, a man-of-war sting is excruciatingly painful, but rarely deadly. But beware—even dead man-of-wars washed up on shore can deliver a sting.

Muscles in the tentacles draw prey up to a polyp containing the gastrozooids or digestive organisms. A fourth polyp contains the reproductive organisms.

Credit : National Geographic 

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You are hearing ordinary sounds echoing and re-echoing as the air inside the shell vibrates. Another roaring sound is the amplified sound of the blood rushing through your own ear!

As lovely as that concept might be, though, it's only a metaphor: When you listen to a shell, you're not really hearing the sound of the ocean. The shape of seashells just happens to make them great amplifiers of ambient noise.

Any air that makes its way into a shell's cavity gets bounced around by its hard, curved inner surfaces. The resonating air produces sound.

The pitch of the sound depends on the size of the shell. Air takes longer to bounce back and forth in a bigger shell than it does in a smaller one, so you'll perceive the pitch of sound emerging from a bigger shell as being lower than that from a smaller one. Whether high or low in pitch, almost all shells sound pleasantly ocean-like.

Credit : Live Science 

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The puffer fish, which puffs itself up when threatened, is one of the world's most poisonous fish. They are eaten in Japan, after careful preparation by a trained chef, who removes the poisonous sac.

This delicacy is known as a fugu and is eaten raw. Many people die each year from eating this dish. The poison paralyses the nervous system and there is no known antidote.

A predator that manages to snag a puffer before it inflates won’t feel lucky for long. Almost all pufferfish contain tetrodotoxin, a substance that makes them foul tasting and often lethal to fish. To humans, tetrodotoxin is deadly, up to 1,200 times more poisonous than cyanide. There is enough toxin in one pufferfish to kill 30 adult humans, and there is no known antidote.

There are more than 120 species of pufferfish worldwide. Most are found in tropical and subtropical ocean waters, but some species live in brackish and even fresh water. They have long, tapered bodies with bulbous heads. Some wear wild markings and colors to advertise their toxicity, while others have more muted or cryptic coloring to blend in with their environment.

They range in size from the 1-inch-long dwarf or pygmy puffer to the freshwater giant puffer, which can grow to more than 2 feet in length. They are scaleless fish and usually have rough to spiky skin. All have four teeth that are fused together into a beak-like form.

Credit : National Geographic 

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This fish cannot fly like a bird, but it leaps into the air, up to 6m (20ft) then glides for about 400m (1,300ft) before splashing back.

There are roughly 40 species of flying fish. Flying fish are tropical and temperate marine species that can be seen off both the Atlantic and Pacific coasts of the United States. They are also found in the Atlantic, Pacific, and Indian oceans. Open oceans provide a habitat for most flying fish, but some live instead on the outskirts of coral reefs.

It’s thought that flying fish evolved a flying mechanism to escape from their many oceanic predators. Once in the air, though, they sometimes become food for birds. Young flying fish may have filaments protruding from their lower jaws that camouflage them as plant blossoms.

Spawning takes place in the open ocean, near the water’s surface. A female deposits eggs, which are attached by sticky filaments to seaweed and floating debris. Newly hatched flying fish have whiskers near their mouths, which disguises them as plants, thus protecting them from predators. A flying fish lives for an average of five years.

Credit : The National Wildlife Federation

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Manatees are large, slow-moving marine mammals. They have stubbly patches of individual hairs here and there on their body. Like their whiskers, their body hair is said to be super sensitive to touch which helps them to navigate the waters with ease. They are graceful swimmers, but have to surface every three or four minutes to breathe air.

Manatees are aquatic herbivores (plant-eaters). Also known as "sea cows," these herbivores usually spend up to eight hours a day grazing on seagrasses and other aquatic plants. A manatee can consume from 4 to 9 percent of its body weight in aquatic vegetation daily.

Manatees use their tails in an up and down motion to propel themselves forward. Strong swimmers, they are capable of reaching speeds of 15 miles per hour in short bursts. Manatees rest from 2 to 12 hours a day either suspended near the water's surface or lying on the bottom, usually for several hours at a time.

While most people tend to see many manatees gathered together at winter warm-water sites, during the rest of the year these animals are semi-social as they travel around the state’s waterways in search of food, mates or places to rest. Except for cow/calf pairs and small mating herds, manatees do not need to travel together although they do socialize when other manatees are encountered.

Manatees reach sexual maturity in 3-5 years (females) and 5-7 years (males) and may live over 65 years in captivity. Gestation is approximately 13 months and usually one calf is born. The calf may stay with its mother (cow) for up to 2 years. Male manatees (bulls) are not part of the family unit. Bulls will leave a cow alone after her breeding period is over. Of the wild manatees that reach adulthood, only about half are expected to survive into their early 20s.

Credit :  FWC

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Scientists have stumbled across a decades-old recording of an Australian musk duck which was able to reproduce sounds and speech, according to an AFP report. It could imitate the noise of a door slamming and someone muttering the phrase. "You bloody fool". Searching through archives, biologist Carel ten Cate found an eerie 1987 recording of "Ripper", a musk duck hand-raised at the

Tidbinbilla Nature Reserve, near Canberra. "You bloody fool," the duck says, over and over, dropping the "1", which is apparently hard for ducks to pronounce. Males of the species emit a musky odour which is what gives them their name.

The recordings had been kept in a sound archive and referenced occasionally until Ten Cate rediscovered them in the course of his research on vocal learning in birds. Ten Cate said Ripper had a bit more in his repertoire – he could also make a noise like the sound of a door closing and its latch clicking.

Some species of animals, and notably birds such as parrots and songbirds, are capable of mimicking human speech. But the phenomenon is rare – if somewhat more common in animals raised by humans. “To find a species quite outside these groups…in a duck, that’s quite extraordinary. So it’s an independent evolutionary occurrence of the ability for vocal learning – that’s very special,” Ten Cate said.

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