My Science School

Oral care experts under the ocean

'Cleaner' fish are much in demand among bigger fish. The cleaner fish are allowed to enter in through the mouth and eat up bacteria and other parasites, thus getting a meal and giving their clients a healthier mouth. However, the fish are known to engage in wrongful actions sometimes they eat mucus or scales, causing a jolt of pain to the client. The client, in return, chases the cleaner fish fiercely, giving the message! Apart from the fact that cleaner fish are too small to make a meal out of, the bigger fish face difficulty finding one. So, usually once trust has been established, the two are inseparable.

A relationship that's spot on!

Tarantulas are scary as it is - the Colombian Lesserblack Tarantula is huge, formidable and capable of eating small creatures! Yet, these mighty tarantulas spare spotted frogs. Maybe they don't taste good, but there's another reason for this special act of kindness. As mighty as they are, these tarantulas still need to protect their eggs from ants. And it turns out that spotted frogs are pretty nifty when it comes to eating up these ants, so living together offers great perks for both.

An assistant for pistol shrimp

The pistol shrimp has one mean weapon that makes other creatures jealous - rapid snapping claws! The shrimp snap their claws so rapidly that a jet of water shoots out in that direction. Despite having this weapon, nature has been cruel enough to give the shrimp lousy eyesight. That's where the goby comes into the picture. Like a guide dog leading its blind owner, the goby lets the shrimp's antennae hang onto its tail fins while it leads the way. In return, the goby gets free accommodation in the shrimp's tunnel, so all's well.

All for a sweet tooth

Meat ants have a mean reputation they're known to be violent towards other meat ants from a different territory as well as other species. Kicking, biting and spraying foul chemicals are some of their classic defence mechanisms. Yet, like everyone else, they have their weakness - a sweet tooth. What do they do to satisfy their need for sugar? They warmly welcome certain caterpillar species to their abode for the sake of the sugary fluid that the meat ants adore. In return, they even carry the caterpillars to places where plants grow so that they can feed. Talk about royal treatment!

Polar bears and arctic foxes

In the snow-filled Arctic world, finding friends and food isn't easy. So when Arctic foxes willingly join polar bears to hunt for prey, the bears don't really complain. As far as they know, the foxes don't cause any major inconvenience and the bears let them eat the scraps. The foxes are glad to get what would normally be difficult to, if they hunted by themselves.

Let's fish together

Last but not the least, dolphins work alongside fishermen! Believe it or not, without any kind of training, dolphins round up fish and alert fishermen when to throw their nets. What do they get in return? Fish that escape the net swim right into their mouths! How much better can it get? Turns out that dolphins interested in helping humans. hang out together in groups.

Picture Credit : Google 

Seals can sleep with half of their brains up and working with the other half completely asleep. This is called 'unihemispheric slow-wave sleep'. It gives a whole new meaning to the term 'sleeping with one eye open' as on the side of the brain that is asleep, the eye will close, and on the side that is awake the eye will be open!

This sleep occurs while they are in the water, but when they come up to sleep on land, they sleep with their whole brains turned off like humans.

The study's first author, University of Toronto PhD student Jennifer Lapierre, made this discovery by measuring how different chemicals change in the sleeping and waking sides of the brain. She found that acetylcholine -- an important brain chemical -- was at low levels on the sleeping side of the brain but at high levels on the waking side. This finding suggests that acetylcholine may drive brain alertness on the side that is awake.

But, the study also showed that another important brain chemical -- serotonin -- was present at the equal levels on both sides of the brain whether the seals were awake or asleep. This was a surprising finding because scientist long thought that serotonin was a chemical that causes brain arousal.

These findings have possible human health implications because "about 40% of North Americans suffer from sleep problems and understanding which brain chemicals function to keep us awake or asleep is a major scientific advance. It could help solve the mystery of how and why we sleep" says the study's senior author Jerome Siegel of UCLA's Brain Research Institute.

Credit : Science Daily 

Picture Credit : Google

The loggerhead turtle is named for its large head, which supports powerful jaw muscles that enable them to feed on hard-shelled prey, such as whelks and conch. Loggerheads are the most abundant species of sea turtle that nests in the United States. Juvenile and adult loggerheads live in U.S. coastal waters, but many adults that nest on U.S. beaches migrate from neighboring nations like the Bahamas, Cuba, and Mexico. 

Loggerhead populations in the United States declined due to bycatch in fishing gear such as trawls, gillnets, and longlines. The use of turtle excluder devices (TEDs) in shrimp trawls, gillnet bans, and other gear modification have reduced sea turtle bycatch in some fisheries, but bycatch in fishing gear remains the biggest threat facing loggerheads. 

Loggerhead turtles have large heads with powerful jaws. The top shell (carapace) is slightly heart-shaped and reddish-brown in adults and sub-adults, while the bottom shell (plastron) is generally a pale yellowish color. The neck and flippers are usually dull brown to reddish brown on top and medium to pale yellow on the sides and bottom. Unlike freshwater turtles and tortoises, sea turtles cannot withdraw their head or flippers into their shells. Hatchlings are mostly dark brown, their flippers have white to white-gray margins, and the  bottom shell is generally yellowish to tan.

Loggerhead turtles, like all sea turtles, are marine reptiles and must come to the surface to breathe air. Adult female sea turtles return to land to lay their eggs in the sand—they are remarkable navigators and usually return to a beach in the general area where they hatched decades earlier.

The life history of loggerhead turtles involves a series of stages of development from hatchling to adult. Hatchlings and juveniles spend the first 7 to 15 years of their lives in the open ocean. Then they migrate to nearshore coastal areas where they will forage and continue to grow for several more years. Adult loggerhead turtles migrate hundreds to thousands of kilometers from their foraging grounds to their nesting beaches. 

Through satellite tracking, researchers have discovered that loggerheads in the Pacific undertake a trans-Pacific migration. Hatchlings from nesting beaches in Japan and Australia migrate across the Pacific to feed off the coast of Baja California, Mexico, Peru and Chile—nearly 8,000 miles! They spend many years (possibly up to 20 years) growing to maturity and then migrate back to the beaches where they hatched in the Western Pacific Ocean to mate and nest and live out the remainder of their lives.

Loggerheads are carnivores, only occasionally consuming plant material. During their open ocean phase, they feed on a wide variety of floating items. Unfortunately, trash and other debris discarded by humans also tends to accumulate in their habitat. Small fragments of plastic are often mistaken for food and eaten by turtles. Juveniles and adults in coastal waters eat mostly bottom dwelling invertebrates such as whelks, other mollusks, horseshoe crabs, and other crabs. Their powerful jaws are designed to crush their prey.

Credit :  NOAA Fisheries 

Picture Credit : Google

Olive ridleys are considered the most abundant sea turtle in the world. They get their name from the coloring of their heart-shaped shell, which starts out gray but becomes olive green once the turtles are adults. They have one to two visible claws on each of their paddle-like flippers. Western Atlantic olive ridleys usually have a darker coloration than eastern Pacific olive ridleys. Adult turtles are relatively small, averaging 2 to 2.5 feet (0.6 to 0.7 meters) in length and weighing 80 to 110 pounds (36 to 49 kilograms). The largest of these animals are observed on the Pacific coast of Mexico.

The olive ridley is found in the tropical regions of the Pacific, Atlantic, and Indian Oceans. In the Pacific, it prefers beaches of Mexico south to Colombia. In the Indian Ocean, its greatest abundance is in eastern India and Sri Lanka. Only a small and declining population of olive ridleys nest in the western Atlantic along the western coast of Africa.

Olive ridleys do not nest along coastal beaches of the United States, but do utilize waters of the southwestern U.S., and sometimes north to the Oregon coast during feeding migration. The olive ridley appears to be more of an open ocean inhabitant, unlike the Kemp’s ridley, which primarily inhabits shallow nearshore coastal waters.

The olive ridley is omnivorous, meaning it feeds on both plants and animals, including algae, lobster, crabs, tunicates, mollusks, shrimp, and fish. Olive ridleys can be found foraging for invertebrates to depths of about 500 feet (150 meters).

Credit : National Wildlife Federation 

Picture Credit : Google

Hawksbill sea turtles inhabit the tropical and sub-tropical waters of all of the world’s major oceans. Hawksbills get their name from their unique beak-like mouth, which resembles that of a hawk and is perfect for finding food sources in hard-to-reach cracks and crevices. They are the only species of sea turtle that can survive on a diet consisting mainly of sponges. Hawksbill turtles play a key role in the function of marine ecosystems.

In many parts of the world, hawksbills face the unique threat of being hunted for their beautiful shell, also known as “tortoise shell”, which is used by craftspeople to create many types of jewelry and trinkets. The historical hunting and killing of hawksbills for their shell nearly drove the species to extinction. Today, the Convention on International Trade of Endangered Species (CITES) forbids the trade of any turtle products on the international market, including hawksbill tortoise shell, but illegal hunting continues to represent a threat to the species in many parts of the world.

Hawksbill turtles have mottled shells consisting of an irregular combination of shades of amber, orange, red, yellow, black and brown. The shells typically have serrated edges, with overlapping scutes.  Their head comes to a tapered point and their lower jaw is V-shaped, giving them a hawk-like appearance. Hawksbills grow up to 2 to 3 feet in shell length and can weigh between 100 and 150 pounds at maturity. Hatchlings are only 2 to 3 inches long and mostly brown in color. Hawksbills have four scales (two pairs) between their eyes and four scutes along the edge of each side of their carapace.

Credit : NOAA Fisheries

Picture Credit : Google

The leatherback sea turtle is the largest turtle in the world. They are the only species of sea turtle that lack scales and a hard shell. They are named for their tough rubbery skin and have existed in their current form since the age of the dinosaurs. Leatherbacks are highly migratory, some swimming over 10,000 miles a year between nesting and foraging grounds. They are also accomplished divers with the deepest recorded dive reaching nearly 4,000 feet—deeper than most marine mammals.

The leatherback turtle has the widest global distribution of any reptile, with nesting mainly on tropical or subtropical beaches. Once prevalent in every ocean except the Arctic and Antarctic, the leatherback population is rapidly declining in many parts of the world. They face threats on both nesting beaches and in the marine environment. The greatest of these threats worldwide are incidental capture in fishing gear (bycatch), hunting of turtles, and collection of eggs for human consumption. The Pacific leatherback turtle populations are most at-risk of extinction. Pacific leatherbacks are one of nine ESA-listed species identified in NOAA’s Species in the Spotlight initiative. Through this initiative, NOAA Fisheries has made it a priority to focus recovery efforts on stabilizing and recovering Pacific leatherback populations in order to prevent their extinction.

NOAA Fisheries and our partners are dedicated to conserving and recovering leatherback turtle populations worldwide. We use a variety of innovative techniques to study, protect, and recover this endangered species. We engage our partners as we develop regulations and recovery plans that foster the conservation and recovery of leatherbacks and their habitats, and we fund research, monitoring, and conservation projects to implement priorities outlined in recovery plans.

Credit : NOAA Fisheries 

Picture Credit : Google

The green sea turtle is the largest hard-shelled sea turtle. They are unique among sea turtles in that they are herbivores, eating mostly seagrasses and algae. This diet is what gives their fat a greenish color (not their shells), which is where their name comes from.

Green turtles are found throughout the world. They nest in over 80 countries and live in the coastal areas of more than 140 countries. Historically, green turtles were exploited for their fat, meat and eggs, causing global population declines. Many countries, including the United States, prohibit the killing of sea turtles and collection of their eggs. However, in some areas, the killing of green turtles for their meat or to supply shells to the wildlife trafficking trade remains a threat to their recovery. Bycatch in commercial and recreational fishing gear, vessel strikes, loss of nesting habitat from coastal development, and climate change are the biggest threats facing green turtles.

NOAA Fisheries and our partners are dedicated to protecting and recovering green turtle populations worldwide. We use a variety of innovative techniques to study, protect, and recover these threatened and endangered populations. We engage our partners as we develop measures and recovery plans that foster the conservation and recovery of green turtles and their habitats. And we fund research, monitoring, and conservation projects to implement priorities outlined in recovery plans.

Credit : NOAA Fisheries 

Picture Credit : Google

Most animals grow old and die. But there are a few exceptions such as the hydra. A tiny, soft-bodied freshwater animal, the tentacle hydra remains youthful because of its regenerative abilities. It carries powerful stem cells which are capable of continuous division, making the hydra renew its body with fresh cells.

Unlike most animals that must worry about old age, disease, or losing a limb, a hydra can constantly replace damaged parts of itself. In certain cases, an entirely new animal can grow from a detached chunk of hydra tissue. On average, they replace all their cells every 20 days, reports Discover magazine’s Katharine Gammon.

Though earlier studies have uncovered some of the secrets behind hydra tissue regeneration, researchers are still looking for answers about how the animal directs its cells to sprout a new head where one was lost. Learning more about the process of regeneration in animals like hydra could potentially lead to new insights about human development, too. In an effort to understand the genetic basis behind the ability, Mortazavi and his colleague Aide Macias-Munoz looked at which genes are switched on and off during head regeneration and how those genes are controlled.

Credit : Smithsonian 

Picture Credit : Google

Giant clams are iconic megafauna. And these creatures face several threats now. What are they?

Though the term megafauna is generally accepted and used to refer to large creatures, research papers have claimed that it sometimes includes smaller creatures and that there may not be any specific scientific approach for defining megafauna. Irrespective of the lack of clarity in the definition, giant clams have been classified as megafauna. Calling coral reef their home, giant clams are the largest aquatic mollusc on Earth, weighing up to 250 kg and one metre long.

They are found in the Indo-Pacific waters, and common in Australian waters. However, the same cannot be said of other regions. Their populations have been over-exploited for meat and shells. Some are said to have gone extinct locally. And so, not surprisingly, nine giant clam species have long been included in the IUCN's Red List of Threatened Species.

It is said that breeding programmes for more than 30 years have helped rebuild over-exploited wild populations in the Pacific Islands, Southeast Asia, and Japan. Even as the demand for their flesh and shell   continues, they're facing new threats "marine heatwaves and acidifying oceans" and "poor water quality and lower light levels caused by sediment-heavy run-off from cities and farms". Just like corals, giant clams have a symbiotic relationship with microalgae. When stressed (due to reasons such as warming waters), the giant clams expel these microalgae and turn white - they bleach, just like corals.

But does this mean giant clams will soon become a thing of the past? Not necessarily. While continuing the breeding programmes, researchers feel that finding new ways to manage clams on coral reefs "such as by seeking out possible new habitat for giant clams and breeding more resilient individuals" - can still save them from these threats. Other suggestions include aquaculture programmes that help baby clams get used to slightly warmer, more acidic and darker waters during breeding and rearing before transplanting them out to the wild" and offering the clams "symbiotic microalgae that are more tolerant to higher temperatures or light levels in early life". The best part? By protecting their habitat, we protect not just the giant clams but also corals, fish, and other invertebrates.

Picture Credit : Google

Blue whales’ average lifespan is estimated at around 80 to 90 years. Scientists can estimate the age of whales by counting the layers of wax-like earplugs collected from deceased animals.

Scientists know little about the life history of the blue whale. The best available science suggests the gestation period is approximately 10 to 12 months. Weaning probably occurs at around 6 to 7 months on, or en route to, summer feeding areas. The age of sexual maturity is thought to be 5 to 15 years. Most reproductive activity, including births and mating, takes place during the winter. The average calving interval is probably 2 to 3 years.

Blue whales are found in all oceans except the Arctic. They generally migrate seasonally between summer feeding grounds and winter breeding grounds, but some evidence suggests that individuals in certain areas might not migrate at all. Information about distribution and movement varies with location, and migratory routes are not well known. In general, distribution is driven largely by food availability—they occur in waters where krill are concentrated.

In the North Atlantic Ocean, their range extends from the subtropics to the Greenland Sea. Blue whales have been sighted in the waters off eastern Canada and in the shelf waters of the eastern United States.

Along the West Coast of the United States, eastern North Pacific blue whales are believed to spend winters off of Mexico and Central America. They likely feed during summer off the U.S. West Coast and, to a lesser extent, in the Gulf of Alaska and central North Pacific waters.

Blue whales with young calves are regularly observed in the Gulf of California (Sea of Cortez) from December through March. It is believed that this area is an important calving and nursing area for the species.

In the northern Indian Ocean, there is a "resident" population. Blue whale sightings, strandings, and acoustic detections have been reported from the Gulf of Aden, Arabian Sea, and across the Bay of Bengal. The migratory movements of these whales are largely unknown but may be driven by oceanographic changes associated with monsoons.

In the Southern Hemisphere, Antarctic blue whales occur mainly in relatively high latitude waters south of the "Antarctic Convergence" and close to the ice edge in summer. They generally migrate to middle and low latitudes in winter, although not all whales migrate each year. Pygmy blue whales (Balaenoptera musculus brevicauda)—a subspecies—are typically distributed north of the Antarctic Convergence and are most abundant in waters off Australia, Madagascar, and New Zealand. An unnamed subspecies of blue whale is found in the southeastern Pacific Ocean, particularly in the Chiloense Ecoregion, and migrates to lower latitude areas, including the Galapagos Islands and the eastern tropical Pacific.

Credit : NOAA Fisheries 

Picture Credit : Google

Ever wondered which animal's heart is the largest in the world? The blue whale's heart. Its heart alone can weigh about 450 kg. It's said that its blood vessels are wide enough for a baby to crawl through.

A blue whale's heartbeat is so loud that it can be heard from almost 2 miles away. But that’s not the only interesting thing about a blue whale’s heartbeat. On average, when it is at the surface of the water, the blue whale's heartbeat is around 25 - 35 beats per minute. However, when it dives deep underwater for food, a blue whale’s heartbeat can drop to almost 4 - 8 beats per minute, and sometimes even 2 beats a minute. This effectively allows the blue whale to minimise the amount of work its heart does while continuing to distribute blood evenly around the body, even at extreme depths and cold underwater temperatures.

Despite being comfortable underwater for upto 30 minutes, whales are mammals, like humans, and must come up to the surface regularly to breathe. Humans however, are involuntary breathers, which means that they don’t need to make a decision whether to breather or not. Breathing is an automatic process for humans and most other mammals. Whales, on the other hand, are conscious breathers, and have to take an active decision, when to breathe. As a result, they never fall asleep completely. Even when they are sleeping, one half of the brain remains awake, to ensure that they don’t drown, while the other half stays awake and alert.

Credit : Practically 

Picture Credit : Google