13November2019

Andaman Chronicle

The Daily Diary of the Islands

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Some of the Strangest Eyes in Nature

Maneka Sanjay Gandhi

Imagine if your nose were to be on top of your head, eyes on your stomach and a mouth on your feet. I’m sure that such an animal exists somewhere, because Nature hasn’t left any combination out.

There is a newly discovered 4 mm marine worm in Scotland, Ampharete oculicirrata, which has a jumble of tentacles near its mouth and beady black eyes poking out of its bottom

Human eyes are among the least useful and become weaker with age, genes or bad nutrition. The animal kingdom has the strangest, most complex eyes in it. From six eyed spiders to geckos that can see 350 times better than humans. Some animals see infrared, and ultraviolet, parts of the spectrum not visible to humans. Some animals even use their eyes to frighten predators or, like butterflies, imitate the eyes of larger animals with completely different parts of their bodies.

Here are some of the strangest eyes in nature-

* Guitarfish don’t have eyelids. But they do have muscles that pull back their eyeballs almost 1.6 inches into their head. This is important because the guitarfish hunts for prey on the ocean floor and this protects the eye from sand.

* Chameleons have cone shaped eyes protruding from their head . Their eyelids join in a circle round the eye leaving only a pinhole for them to look through. Their eyes move independently of each other, so they can look in different directions at the same time. Each eye can move a full-360 degrees, which allows a chameleon to watch an approaching object while simultaneously scanning the rest of its environment. When the chameleon sees prey, it focuses both eyes in the same direction and shoots out its tongue at high speed, a technique that requires a very precise distance and depth perception. Chameleons have very sharp eyesight, being able to see an insect several meters away, and they can see ultraviolet light.

* The colossal squid has the largest eyes of any animal on the planet. They are nearly 11 inches across — about the size of soccer balls, with lenses the size of oranges. Each eye has photophores (light organs that work similar to headlights) that produce light for the squid to see its prey in the dark, useful for an animal that hunts 2,000 meters below the surface.

* Dragonflies have eyes that consist of thousands of thousands of tiny hexagonal eyes, giving them nearly 360-degree vision.  Their eyes are so big that they cover most of their head. These eyes are made up of 30,000 visual units called ommatidia, each one containing a lens and a series of light sensitive cells. They can see ultraviolet and polarized light. They have three smaller eyes, named ocelli, capable of detecting movement, allowing them to react within a fraction of a second.

* The leaf-tailed gecko has vertical slit-like eyes without eyelids. Its vertical pupils contain a series of “pinholes” that widen at night, allowing for amazing night vision, even seeing colours at night.  In fact, the leaf-tailed gecko can see 350 times better than humans! The pattern on the whites of their eyes is part of the full-body camouflage. Their eyes are protected by a transparent membrane and geckos clean this with their tongue.

* Goats have rectangular pupils which give them a 320 – 340 degree field of vision (compared to humans’ 160 – 210 degrees), and better peripheral and night vision. They can see virtually all around  without having to move.

* The nocturnal ogre-faced spider has six eyes. It has amazing night vision, 100 times better than humans, not only because of its large eyes, but also because of a light-sensitive layer of cells covering them. This membrane is so sensitive that it is destroyed at dawn and a new one is produced every night.

* Mantis shrimps, aggressive predators, have the most complex eyes of any animal on Earth. They are  two googly eyes, like muffins mounted on stalks compound like a dragonfly, but they have 12 colour receptors (humans have three), as well as ultraviolet, infrared and polarized light vision. Each of the mantis shrimp’s eyes is divided in three sections, allowing the creature to see objects with three different parts of the same eye. In other words, each eye has “trinocular vision” and complete depth perception, meaning that if a mantis shrimp lost an eye, its remaining eye would still be able to judge depth and distance as well as a human with his two eyes. While they have only 10,000 ommatidia per eye, in the mantis shrimp each ommatidia row has a particular function. For example, some of them are used to detect light, others to detect colour, etc. The eyes are located at the end of stalks, and can be moved independently from each other, rotating up to 70 degrees. Interestingly, the visual information is processed by the eyes themselves, not the brain.

* Spookfish have four eyes and ghost-like bodies. Most animals on Earth have eyes that use lenses to focus light and to see. Spookfish are different. Each eye has a swelling called a diverticulum, separated from the main eye by a septum. While the main part of the eye has a lens and functions in a similar way to other animal eyes, the diverticulum has a curved, composite mirror composed of many layers of guanine crystals. This “mirror” reflects light and focuses it onto the retina allowing the fish to see both up and down at the same time.

* Sea Stars, or starfish, have five eyes capable of sensing lightness and darkness — one on the end of each arm.

* Tarsiers, squirrel sized primates, have the largest eyes on Earth, relative to body size. They can’t move their eyes around but they can turn their heads 180 degrees in either direction to scan for prey or predators. With each eye weighing more than its brain, the tarsier has extremely acute eyesight and superb night vision, even seeing ultraviolet light.

* Four eyed fish, found in fresh or brackish water, feed on insects, so they spend most of their time swimming at the surface. Despite their name, four eyed fish have only two eyes. However, these eyes are divided by a band of tissue and each half of the eye has a pupil of its own. This bizarre adaptation allows the four eyed fish to see perfectly, and at the same time, both above and below the waterline, scanning for both prey and predators. The upper half of the eyeball is adapted to vision in air, while the lower half is adapted to underwater vision. Although both halves of the eye use the same lens, the thickness and curve of the lens is different in the upper and lower eye halves, correcting itself for the different behaviour of light in air and water.

* Stalk eyed flies have long stalks on the sides of the head with the eyes and antennae at the end. Male flies usually have much longer stalks than females and females prefer males with long eyestalks. Males, during mating season, often stand face to face and measure their eyestalk’s length; the one with the greatest “eye span” is the winner. Male stalk eyed flies also have the extraordinary ability to enlarge their eyestalks by ingesting air through their mouth and pumping it through ducts in the head to the eyestalks. They do this during mating season.

And these are just a few. Next time I will explore why and how eyes have evolved to be what they are. 

To join the animal welfare movement contact This email address is being protected from spambots. You need JavaScript enabled to view it. , www.peopleforanimalsindia.org

  • Written by Denis Giles
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Mortality Rates for Fungal Diseases

Maneka Sanjay Gandhi

Candida auris is a dangerous fungal infection that emerged in 2009 in Japan and has now spread round the world, especially in hospitals. It is a superbug: a germ that has evolved defences against medicines and cannot be treated. These include antifungals such as fluconazole (Diflucan), the antifungal drug of choice in many countries, and recently introduced antifungals known as echinocandins. First identified in Japan in 2009 after isolation from a patient’s ear, it is responsible for the rapidly increasing, hospital-acquired, invasive infections worldwide. It is a threat to intensive care units, because it can survive normal decontaminants such as chlorhexidine and bleach. Some hospitals have had to rip out floor and ceiling tiles to get rid of it.

If it gets into the bloodstream it can be life threatening. People with weakened immune systems are the most vulnerable - newborns, the elderly, people who have other infections, diabetics, people who have undergone antibiotic or antifungal therapy.

The rise of C. auris has been little publicized, in part because it is new. Outbreaks have been kept confidential by hospitals, doctors, even governments, as publicizing them would scare people into not going for other treatment. In America, the Centre for Disease Control is not allowed to make public the name of hospitals involved in outbreaks.

The symptoms of C. auris — fever, aches, fatigue — are not unusual, so it is hard to recognize the infection without testing. It is frequently misdiagnosed. One sign is that fever and chills  don't subside after being treated with antibiotics. Coma, organ failure and death may occur if appropriate treatment is delayed. Around 30-50 percent of patients, who contract Candida auris, die. The fungus can live for a long time on patients' skin, and in health care facilities, allowing it to spread to new patients.

Why is it spreading so rapidly across the globe ?

1. One reason is the indiscriminate doling out of antibiotics and antifungals by the medical community. This allows microbes to adapt, evolve and outsmart drugs. Without antimicrobials that work, common medical procedures, like hip operations, C-sections, or chemotherapy, have become more dangerous, and medical interventions — organ transplants, chemotherapy — may become impossible to survive. Gonorrhoea, certain strains of tuberculosis to name a few, no longer respond to any medicine.

2. The more important reason is that each country uses the same drugs on animals grown for food. In India we use tonnes of antibiotics and antifungals in poultries, piggeries. Animals are forcibly grown in such terrible conditions that keeping them alive, till they are large enough to be killed, is impossible without them. This applies in India mainly to the poultry industry, which has overstuffed birds in filthy cages with their beaks and toes cut off, infested with mites and fed rubbish. Their antibiotic/antifungal laced faeces spreads in land and water.  We eat contaminated food and drink contaminated water.

80% of India’s antibiotics are used to promote livestock and poultry growth, and protect the animals from the bacterial consequences of the filthy environments in which they are grown. In America 34 million pounds a year of antibiotics are used. In India it is more than that. According to the latest WHO surveys India is the largest user of antibiotics and fungicides in the world – and the country that originated the germ resistant to all medicine - the superbug.

3. Modern agricultural practices also depend on these drugs. C. auris’s resistance is traceable to industrial agriculture’s mass application of fungicides used in diverse crops like wheat, banana, barley, soyabeans, apples, grapes, soft fruits, corn, among  others.

In a paper “Worldwide emergence of resistance to antifungal drugs challenges human health and food security” by scientists Matthew C. Fisher and colleagues published in Science  2018, six main classes of fungicides – azoles, morpholines, benzimidazoles, strobilurins, succinate dehydrogenase inhibitors, anilinopyrimidines -  have been identified, which were hardly used in agriculture before 2007. It is not a coincidence that the fungi affecting us have all turned into superbugs in that period.

Azoles, used in both crop protection and medical settings,  are broad-spectrum fungicides, annihilating a wide range of fungi rather than targeting a specific type. They are now 26% of all fungicides used.

Candida auris is not the only deadly fungus which is showing multidrug resistance. One fungus, Aspergillus fumigatus, has been killing 2 lakh people every year. This species colonizes decaying vegetation in fields, forests, and compost heaps. It attacks immunocompromised humans. Azole antifungals itraconazole, voriconazole, and posaconazole have long been used to treat pulmonary asperillogosis, the infection caused by A. fumigatus, but in the last ten years it has developed a resistance to antifungal drugs. Studies, comparing long-term azole users and patients just beginning to take the drug, have shown that drug-resistant A. fumigatus was prevalent in both groups, showing clearly that the resistance has come from the food they are exposed to, rather than the medicines they were taking. Studies done in Bogota, Columbia, found  A. fumigatus in agricultural fields using fungicides. Soils were sampled from an array of crop fields treated with itraconazole or voriconazole fungicides. A. fumigatus was grown in the lab on agar treated with the same antifungals. In more than 25% of cases, A. fumigatus persisted despite the fungicide treatment. This simply means that, due to agricultural practices, Aspergillus is entering hospitals already adapted to the antifungals designed to check its spread.

Drug resistant strains of  Candida albicans,  C. glabrata and Cryptococcus neoformans, have also been recently reported. Candida glabrata has become the main bloodstream pathogen recovered from patients. There is also a growing threat from pathogenic fungi such as Aspergillus terreus, Scedosporium spp., Fusarium spp., and members of the Mucorales.

Azole fungicides need to be banned in crop management. The dangers of continuing upon this path of agricultural management are acute. Twenty-five forms of agricultural azoles are in use, compared to just three forms of medical azoles. Obviously, the medical use of azole based antifungals is ineffective. Azoles are increasingly failing as frontline therapies, with patient mortality approaching 100% . The rate of emergence of fungicide resistance is greater than the pace of fungicide discovery. This situation parallels the situation for antibiotics

But, instead of intervening in the interests of public health to limit azoles, government policy in recent years has promoted their expansion, fostering conditions for virulent drug-resistant fungi. Global sales have tripled since 2005, from $8 billion to $21 billion in 2017. Azoles are used not only for human and animal health care and crop protection, but also in antifouling coatings and timber preservation. Fungicides have expanded  in sales and in geographic distribution. In each new area fungicides percolate into the local environment. In 2012, USGS scientists studied 33 different fungicides used in potato production and found at least one fungicide in 75% of surface water and 58% of ground water samples.

As climate change brings higher overall temperatures and vacillation between drought and heavy rainfall, fungi will spread outside their current ranges. Aspergillus flavus, the producer of a cancer-causing aflatoxin that reduces corn yields and poisons humans, thrives in drought conditions and large crop-water deficits.

Instead of government blaming farmers for illiterate overuse, or using this opportunity to get more GMO gene manipulated seeds, or looking at different drug cocktails that will spew more poison into the environment, agricultural practices will have to be modified to bring back organic food, sustainable crop rotation and intercropping. There is enough evidence to show that this can greatly reduce the presence of fungal diseases. For instance, intercropping soya with flax removed all pathogenic fungi. Researchers in India find that if, instead of using azole fungicide to control potato blight, silica is applied  to the leaves, disease infestation comes down sharply. Surrounding crops, with wild non-crop vegetation, also control fungal pathogens.

We are in a vicious spiral. As we use more fungicides, more and more resistant pathogenic fungi emerge. Fungi have highly plastic genomes and adapt rapidly. We are seeing the continual emergence of new races of plant-infecting fungi able to overcome both host defences and chemical treatments. The first case of resistance against the benzimidazoles (MBCs) was reported in 1969, and now MBC resistance is known to occur in more than 90 plant pathogens. Azole resistance in a plant pathogen was first reported in 1981. Resistance to strobilurins was reported in field trials even before commercial introduction, and in wider field populations within 2 years of release. A new generation of succinate dehydrogenase inhibitors was introduced in 2007, but by 2017 resistance were found in 17 pathogen species. Today, crop-destroying fungi account for annual yield losses of 20% worldwide, with a further 10% loss postharvest.

By doing intensive farming, and using broad-scale pesticide applications, we breed out the plants’ own defences. In parallel, the number of humans at risk from fungal infections is rising rapidly. To avoid a global collapse in our ability to control fungal infections, and to avoid critical failures in medicine and food security, we must put public health before company fiscal health.

The global mortality rate for fungal diseases now exceeds that for malaria or breast cancer, and is comparable to those for tuberculosis and HIV. But no Indian government has even applied its mind to this huge problem. The pesticide ministry is in one corner, far away from the health ministry, and the two have never met to discuss issues like this. 

To join the animal welfare movement contact This email address is being protected from spambots. You need JavaScript enabled to view it. , www.peopleforanimalsindia.org

  • Written by Denis Giles
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Intelligence Doesn’t Belong to One Dictating Alpha

 

Maneka Sanjay Gandhi

Ants and bees have become paragons of a system that’s coordinated but without central control. Intelligence does not belong to one dictating alpha, but is distributed across the entire group. Two types of intelligence operate in a group : adaptive - which means decisions stem from the interplay between individuals, and collective - a group of agents acting together as a single cognitive unit.

Organisms are inherently competitive, yet cooperation is widespread. Genes cooperate in genomes, cells cooperate in tissues, and individuals cooperate in societies. Traditionally, when human societies weren’t as big as they have become, healthy, enduring social structures amongst humans were formed in small family and tribal units and lasted for centuries. In contrast, when humans have attempted to gather in nations and empires, endless troubles, power-struggles and instabilities have emerged.

For both, humans and animals, living in a group makes sense because there are many more beings to provide vigilance and defence, mating is easier, help is available, heat is conserved better. Foraging is easier. So is babysitting, feeding, sleeping, huddling, hibernating, and migrating.

Animals may aggregate by mutual attraction to each other, or by mutual attraction to limited resources. Bark beetles form large aggregations by mutual attraction to the bark of a fallen log and also to the odours of other members of their species.

Once animals are grouped, a mechanism comes into play that makes group living efficient. In some treehopper aggregations, nymphs communicate the threat of a predator by using vibrations, which humans can detect only with electronic instruments. Eastern tent caterpillars stay in a communal tent that increases in size as they grow and add silk. Colony members leave the tent on brief forays to feed on foliage and lay chemical trails for other group members to follow. In colony birds, such as cliff swallows, unsuccessful individuals often watch other birds returning to their nests with food and follow them to productive foraging sites. Pack of hyenas or wolves cooperate to bring down a zebra.

Migration in herds is common and can involve huge numbers of individuals. More than one million blue wildebeest migrate in a clockwise fashion over the plains of East Africa, covering a distance of over 2,500 km each year in search of grass. The African desert locust swarms cover as much as 200 square km, billions of individuals moving cohesively in search of food.  The now-extinct passenger pigeon of North America, hunted to death for sport, migrated in groups of millions in search of food.

In long-term, stable social groups interactions among members are often altruistic. For example, when a ground squirrel sounds an alarm call to warn other group members of a nearby coyote, it draws the coyote’s attention and increases its own odds of being eaten. Similarly, a female meerkat forgoes reproduction and, instead, feeds the young of another group member.

Over a period of time group living also gives rise to new behaviour. Humans are not the only ones that indulge in nepotism : apes also have preferential treatment of kin, hierarchies in societies are also developed by monkeys and chickens, and individuals form alliances within groups.

Like humans, animals form complex societies. Fish too have groups based on business opportunities. Cleaner fish are in charge of chewing off parasites from the bodies of bigger fish in coral reefs. Over the years they have developed a distinctive blue-yellow uniform colour and stand in groups. Cleaners also have an enforceable customer service code. If they accidentally end up biting a customer, rather than cautiously nibbling off the parasites, the other cleaners punish the irresponsible worker. It’s one of the only observed instances of a species punishing members in a systematic fashion.

Chimpanzees run efficient military operations. During a 10-year study research on a community of chimps in Uganda, scientists found that every so often, groups of chimp males would form up and head north, towards the border between their territory and the neighbouring tribe’s land. They would stealthily move through the jungle in single-file, with practically no eating, or socializing. They would cautiously look for signs of individuals from the other tribe, such as faeces, abandoned termite-fishing tools, etc. When they found a member of the northern tribe on his own, they would kill him right away. After analyzing the pattern, scientists found that the chimpanzees were at war. They were fighting over land and doing it in a very organized way. In Tanzania, researchers witnessed a civil war when one section of angry chimps split from the larger group. Over the next five years, the  breakaway group destroyed the original tribe with a series of sudden, well thought out attacks.

Monkeys always seem to be grooming one another. But more than altruistic group activity, picking lice out of fur is their currency. Females trade grooming for sex, for instance. Researchers saw females would sleep with someone in exchange for eight minutes of grooming. This system obeys the law of supply and demand -- when there were fewer females around, the price went up to 16 minutes of grooming for sex. Grooming isn't exchanged for only sex. Female monkeys groom other females in exchange for favours (for instance, in order to hold their infants for a specific amount of time). When scientists trained a velvet monkey to open crates containing apples for the other monkeys, soon she was the most well-groomed monkey in the group (In a community of monkeys, "rich" monkeys are distinguished by how nice their fur looks). Then they trained another monkey to do the same thing. Sure enough, the amount of grooming the first monkey got dropped in half. 

50 million years before humans thought of growing their own food, ants were already practicing the art of group sustainable agriculture. Leafcutter ants take cut up bits of plants into their ant-hills and, instead of eating them, they lay the bits down and defecate on them so that fungus starts growing. They cultivate this fungus and protect it from other, non-edible fungi – they are not only farming, they’ve also made safe and effective pesticides.

Orcas teach each other everything – from singing, eating new foods to fishing. One of the orca whales at Marine Land, Canada, evolved a brilliant bird-catching method: he would take some fish, chew them and spit them out on the surface of the water as bait. When a bird dived down for the easy meal, the whale would leap up and eat the bird. Soon, the other orcas started doing the same.

Cuttlefish live in schools. They can split their bodies into different patterns to accomplish different things at the same time. One half of its body may be designed to attract a mate, while the other half is a completely different design to conceal itself from predators. They employ shape-shifting strategies to conceal themselves as coral or algae. A cuttlefish has maybe ten million little colour cells in its skin. It can assess the colour and texture, of their surroundings and emulate it in seconds. They even use certain colours to assert dominance in their group.

When frightened, most humans in groups forget the welfare of others and try any means of surviving. That is what causes panic rushes during fires and being trodden over by people in a rush to escape. Sheep do the same. As sheep have limited means of defence from predators, their main defence mechanism is to instinctively flock together and flee from danger. Research has also shown that, instead of fleeing randomly when faced with danger, sheep head straight for the centre of the flock. According to a study done by Andrew King, and published in Current Biology , the strongest sheep will fight their way to the centre, which offers them greater protection.

To join the animal welfare movement contact This email address is being protected from spambots. You need JavaScript enabled to view it. , www.peopleforanimalsindia.org

 

  • Written by Denis Giles
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