My Science School

There is a pink bottlenose dolphin known as "Pinky" in Louisiana. She is believed to be an albino dolphin which is missing melanin, the pigment that gives colour to skin and eyes. She was first spotted as a calf in 2007 in Lake Calcasieu.

Pinky was first spotted in June 2007 by a boat captain, Erik Rue. In 2015, Rue was able to capture photo evidence of Pinky mating, proving that she is female. The dolphin has become a tourist attraction, and conservationists have asked visitors to leave the dolphin alone. Pinky's behavior is similar to the rest of the dolphins in her pod, although she tends to spend more time underwater.

Although it is quite rare to see an albino animal in the wild, Pinky has a few signs that appear confirm her albinism. Blood vessels and eyes with a red-ish hue can be seen through Pinky's skin, a key indicator that the cells that normally make pigment melanin, are hardly active in this dolphins body. Although albinism can be hereditary, it is unknown if Pinky's parents were of a pinkish/white hue or if they simply carried the specific mutation of a gene that they passed down to Pinky.

In 2017, a video was taken showing two albino dolphins swimming in the lake, presumed to be Pinky and her calf.

Picture Credit : Google

Before the first trip round the whole world, the ocean was called “ocean sea”, but it is when Magellan was sailing the world ocean that he decided to call the ocean “Pacific” when he realised that the ocean he was sailing on was calm. From then, all parts of the world ocean were given a name: Atlantic Ocean, Indian Ocean, Austral Ocean, Arctic Ocean. If we look into the definitions of “ocean” and “sea” we notice that the difference between the two is very subtle. However, there are a few points that help us distinguish a sea from an ocean.

We often hear that size does not matter but in the maritime field it does. Indeed, it is a matter of size! It is the huge surface area of the ocean that easily distinguishes it from the sea. Even if the sea is also defined as a large body of salt water, its surface area is smaller. To give you a reference, the biggest sea (Arabian Sea) has a surface of 3.6 million km² whereas the smallest ocean (Artic Ocean) has a surface of more than 14 million km².

The difference between the sea and the ocean does not stop here, it is also a matter of borders! If we look into the definition of the ocean, it is written that an ocean is always surrounded by continents.

The borders and size of the water body are not the only distinctions between ocean and sea. Indeed, the salinity of water is also a factor to take into account.

Surely, it is not by comparing the taste of water that you can distinguish the ocean from the sea, even if the water in the oceans is less salty than in the seas (the salinity of oceans is on average of 35g/L). Why are seas saltier? Ocean currents enable to regulate the salinity of oceans thanks to thermohaline circulation. To understand this phenomenon better, we invite you to read our article about ocean currents.

On the other hand, seas are saltier because of more important water evaporation. As salt does not evaporate, thus sea water has a higher density of sodium chloride.

Credit : Ocean Clock

Picture Credit : Google

The Sargasso Sea located within the Atlantic Ocean is the only sea without a land boundary. It is surrounded by ocean currents on all sides. It's different from the other parts of the Atlantic Ocean because of the presence of the brown sargassum seaweed. Mats of the free-floating weed provide shelter to many marine animals such as white marlin and salmon shark.

Sargassum provides a home to an amazing variety of marine species. Turtles use sargassum mats as nurseries where hatchlings have food and shelter. Sargassum also provides essential habitat for shrimp, crab, fish, and other marine species that have adapted specifically to this floating algae. The Sargasso Sea is a spawning site for threatened and endangered eels, as well as white marlin, porbeagle shark, and dolphinfish. Humpback whales annually migrate through the Sargasso Sea. Commercial fish, such as tuna, and birds also migrate through the Sargasso Sea and depend on it for food.

While all other seas in the world are defined at least in part by land boundaries, the Sargasso Sea is defined only by ocean currents. It lies within the Northern Atlantic Subtropical Gyre. The Gulf Stream establishes the Sargasso Sea's western boundary, while the Sea is further defined to the north by the North Atlantic Current, to the east by the Canary Current, and to the south by the North Atlantic Equatorial Current. Since this area is defined by boundary currents, its borders are dynamic, correlating roughly with the Azores High Pressure Center for any particular season.

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Manatees constantly grow molars, but are incapable of biting anyone. These gentle marine mammals eat seagrass many hours a day. The sand granules eaten along with the grass wear down their teeth which eventually fall off. As the front teeth fall off the molars at the back get pushed forward, which is why they are called "marching molars."

Manatees were once thought to be mermaids by early sailors, including Christopher Columbus, who described the “mermaids” as less beautiful than he imagined with masculine faces. In fact, manatees belong to the order Sirenia, which derives its name from the sirens (or mermaids) of Greek mythology. A common myth regarding manatees is they are an invasive species in Florida imported to control exotic aquatic plants. Florida manatees are in fact native to the United States, as seen in both the fossil records and in Native American sites. Depending on the time of year they can be frequently found in Florida, Alabama, and Georgia. On very rare occasions Florida manatees have been seen as far north as Massachusetts!

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.

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When one hears the word "migration", what one thinks of is perhaps the large-scale wildebeest migration in Africa, or even the seasonal migration of birds between countries and continents. Did you know several other creatures - including marine - also migrate? Let's take a look at one such annual event that happens underwater.

Occurring from May through July/August, South Africa's east coast hosts a spectacular annual migration of sardines. What makes this spectacular? Consider this in the blue waters of the Indian Ocean, millions of sardines move in silvery masses that can totally be a few km wide, many km long, and several mt deep. To add to the drama, tens of thousands of birds, including cormorants, terns, and gulls swoop down on the shoals, while dolphins, sharks, whales, seals, and even some species of fish gobble up these sardines. "Bottlenose and common dolphins work together in a sheepdog fashion, forcing thousands of fish at a time into 'bait balls, forcing them closer to the surface where they can pounce on" the fish.

The sardine run attracts even humans, making it a phenomenon of great economic significance too-while fisherfolk catch and sell fish, many tourists use this occasion to watch sharks, dolphins, whales, etc. Though this migration is large, in terms of sheer number, it is not as well-known or well-documented as the wildebeest migration occurring on the same continent. It is also not clear what causes the migration, though there are several theories. One is that it is a seasonal reproductive migration, and another states that as cold-water fish, they migrate to avoid the seasonal warm currents and reach places with cooler currents. Irrespective of their reasons for migration, what is of concern is that the run may no longer be a phenological event. A phenological event is a biological event that occurs at the same time every year. A study found that over the last 66 years, "sardines arrived off the coast of Durban increasingly late- at a rate of 1.3 days later per decade. Over the six decades this has meant the date has changed from arrivals as early as mid-June at the beginning of the record to dates as late as mid-July in the last decade".

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Tardigrade is a phylum, a high-level scientific category of animal. (Humans belong in the Chordate phylum — animals with spinal cords.) There are over 1,000 known species within Tardigrade, according to Integrated Taxonomic Information System (ITIS).

In many conditions, they survive by going into an almost death-like state called cryptobiosis. They curl into a dehydrated ball, called a tun, by retracting their head and legs. If reintroduced to water, the tardigrade can come back to life in just a few hours.  

While in cryptobiosis, tardigrades' metabolic activity gets as low as 0.01 percent of normal levels, and their organs are protected by a sugary gel called trehalose. They also seem to make a large amount of antioxidants, which may be another way to protect vital organs. Water bears also produce a protein that protects their DNA from radiation damage, according to research by the University of Tokyo.

In cold temperatures, they form into a special tun that prevents the growth of ice crystals. 

Tardigrades reproduce through sexual and asexual reproduction, depending on the species. They lay one to 30 eggs at a time. During sexual reproduction, the female will lay the eggs and the males will fertilize them. In asexual reproduction, the female will lay the eggs and then they will develop without fertilization. 

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Tardigrades, also known as water bears, are microscopic, usually about 0.5 mm long. These water-dwelling, eight-legged micro-animals can survive extreme heat and cold, besides even radiation in space. They are often found on mosses and lichen. Did you know when short on water they can dry out for years and revive without any damage when reintroduced to water?

Tardigrades are semi-aquatic. They can survive in watery as well as terrestrial environments — from oceans and lakes to mountains, forests and sand dunes. They're found all over the world, from frigid Antarctic glaciers to active lava fields. They’re most commonly found living in moss.

Most tardigrades eat algae and flowering plants, piercing plant cells and sucking out their contents though their tube-shaped mouths. Some, however, are carnivorous and may eat other tardigrades.

Tardigrades are nature’s pioneers, colonizing new, potentially harsh environments, providing food for larger creatures that follow. Scientists say, for instance, that tardigrades may have been among the first animals to leave the ocean and settle on dry land.

Tardigrades pose no threat to humans. Scientists have yet to identify a species of tardigrade that spreads disease.

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The barreleye is a small fish with a completely transparent head, found in the depths of the Pacific Ocean. It has light-sensitive tubular eyes that can rotate within a see-through, fluid-filled shield covering its head. The fish lives close to the depth of the ocean where sunlight barely reaches. Its eyes, capped by bright green lenses, help in its search for prey overhead in the dark waters.

Barreleyes inhabit moderate depths, from the mesopelagic to bathypelagic zone, circa 400–2,500 m deep. They are presumably solitary and do not undergo diel vertical migrations; instead, barreleyes remain just below the limit of light penetration and use their sensitive, upward-pointing tubular eyes—adapted for enhanced binocular vision at the expense of lateral vision—to survey the waters above. The high number of rods in their eyes' retinae allows barreleyes to resolve the silhouettes of objects overhead in the faintest of ambient light (and to accurately distinguish bioluminescent light from ambient light), and their binocular vision allows the fish to accurately track and home in on small zooplankton such as hydroids, copepods, and other pelagic crustaceans.

The bioluminescent organs of Dolichopteryx and Opisthoproctus, together with the reflective soles of the latter, may serve as camouflage in the form of counterillumination. This predator avoidance strategy involves the use of ventral light to break up the fishes' silhouettes, so that (when viewed from below) they blend in with the ambient light from above. Counterillumination is also seen in several other unrelated deep-sea families, which include the marine hatchetfish (Sternoptychidae). Also found in marine hatchetfish and other unrelated families are tubular eyes, such as telescopefish and tube-eye.

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Do you know what keeps marine creatures such as seals, whales, and walruses warm in the chilly waters they inhabit? Blubber. It is a thick layer of fat right under the skin of marine mammals, and covers their entire body, except for their fins, flippers, etc. In addition to insulating the animals, it stores energy and increases buoyancy. So one can imagine how integral the blubber is to these mammals existence. But the sea otter, among the smallest of marine mammals, has no blubber at all. And how it stays warm has been a mystery.

Otters are found on all continents, except Australia and Antarctica. They inhabit both freshwater systems such as rivers, lakes, and wetlands, and marine ecosystems. The sea otter is found in the Pacific Ocean. It has been known all along that the sea otter's thick and water-resistant fur offers it some help with heat loss. But that isn't enough to protect itself from the cold water of Alaska, where a lot of these otters reside. Scientists also knew "the sea otters burn a lot of energy - approximately three times greater than predicted for mammals of their size, and to keep up with the demand, they may consume up to 25 percent of their body mass in a day". But what they could not find out was "which tissues were making use of this energy and how it was going towards producing heat".

And that is what a new paper published in a journal discloses - these creatures have a unique energy conversion system whereby their muscle tissue "leak" large amounts of heat throughout their bodies. Normally, a living creature's metabolism rate is linked to its activity level. In the case of a sea otter, the metabolism is high but without much activity. So this metabolic energy is being lost as heat rather than being used for powering its muscles. As a news report quotes the lead author of the paper, "they're really good at making heat by being inefficient. The team behind the study found that this "thermogenesic effect was present in sea otters from the time they were babies to adults.

Apparently, this effect is presumed to be prevalent among animals in the polar regions, but seen for the first time in these marine creatures. The study's lead author also imagines that understanding this metabolic system could help find solutions to obesity in humans.

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