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bio-facts · 3 years

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Under Pressure - Freddie Mercury ft marine animals

Thank you @phylcian for asking me to make this post! I hope it helps you! :)

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Primero, por qué nosotros o cualquier otro mamífero terrestre no puede sobrevivir a la presión que ejerce la columna de agua?

La presión hidrostática puede llegar a ser descomunal, por cada 10 metros que aumenta la profundidad, la presión se incrementa en 1 atmósfera. La profundidad máxima registrada es de 10.790m en la Fosa de las Marianas, A esa profundidad, la presión es 1.100 veces la experimentada en la superficie.

Nosotros tenemos cavidades con aire (fosas nasales, oídos, vasos sanguíneos, pulmones…) y los gases se pueden comprimir, su volumen es fácilmente modificable. A gran profundidad, la presión comprime los gases fuertemente, lo que lleva al colapso de las estructuras que lo rodean, dañándolas de forma irreversible.

Qué hacen los animales marinos para combatir esto?

Fuera las cavidades que puedan acumular aire. En su lugar, sus cuerpos son mayoritariamente agua, porque los líquidos no pueden comprimirse, -o al menos no con tanta facilidad como los gases, y cuesta mucho más modificar su volumen. Por esta razón, los peces abisales tampoco poseen de vejiga natatoria (un órgano grande con aire en su interior, que permite a los peces que se encuentran en la superficie flotar o hundirse en el agua).

Cuerpos pequeños: no necesitan ni quieren petisuis. Sus cuerpos suelen ser blandos, con estructuras esqueléticas también pequeñas y blandas (huesos dúctiles) Piensa en una pelota antiestrés; es blanda y cuando la aprietas modifica fácilmente su forma, pero si la pelota es dura, podrías incluso romperla. Esto lo que les permite también es no tener ningún tipo de oquedad; espacios huecos en el interior que puedan ser rellenados con gas.

El hecho de que sean pequeños, aporta poca superficie corporal, lo que permite que la presión del agua de su interior esté en equilibrio con la presión del agua del medio.

A nivel citológico y químico, nos encontramos con unas adaptaciones interesantes:

Bicapa lipídica: la membrana de las células es grasa, y en el caso de los animales está formada por ácidos grasos saturados, mientras que la de los vegetales son ácidos grasos insaturados. Que estén o no saturados va a influir en la fluidez de membrana y su permeabilidad, lo cual influye en la estructura de la membrana, y por tanto en la interacción de las cargas.

La fluidez de la membrana también depende de la temperatura, y no olvidemos que la presión no es la única condición extrema que encontramos ahí abajo; la temperatura oscila entre los 4ºC y 1ºC. Los animales de aguas profundas aumentan su porcentaje de ácidos grasos insaturados, porque éstos permanecen líquidos a bajas temperaturas (fundamental para el correcto funcionamiento de la célula) y mantienen las membranas elásticas. Para ilustrarlo, imagina, por ejemplo, un trozo de tocino (grasas saturadas) sobre agua, y ahora aceite (grasas insaturadas) sobre agua. El aceite es más fluido, y bajo presión puede moverse mejor que el tocino.

Proteínas: para que funcionen correctamente, las proteínas deben de ser capaces de cambiar su forma y tamaño, ya que normalmente suelen agrandarse. Bajo presión, esto resulta difícil, como Jeffrey Drazen explica; “Una simple analogía es la de inflar un globo. Es fácil hacerlo en aire, pero intenta hacerlo en el fondo de una piscina”. Así, la presión tiene un efecto paralizante en las proteínas, desnaturalizándolas cuando penetra el agua en su interior hidrofóbico.

Para evitar esta inhabilitación de las proteínas, los animales de los fondos recogen unas moléculas orgánicas llamadas piezolitos en sus células. Estos piezolitos se unen fuertemente a las moléculas de agua, lo que les proporciona a las proteínas más espacio y evita que el agua ingrese al interior de las proteínas y las distorsione. A más profundidad, más piezolitos tienden a acumular las células. El piezolito por excelencia, dada su presencia universal en los organismos marinos, es el óxido de trimetilamina (TMAO), que también es el responsable de aportarles a los peces su olor característico.

Los elasmobranquios tienen una gran cantidad de urea en su sangre, un compuesto orgánico que es tóxico. El TMAO no sólo estabiliza las proteínas, sino que también neutraliza los efectos dañinos de la urea. La cuestión es que la presión puede provocar que este tipo de moléculas se vuelvan más o menos tóxicas. Por esta razón, los tiburones de los fondos marinos acumulan más TMAO que sus primos.

Estas son una de las muchas adaptaciones que existen, si bien no se conoce al 100% el funcionamiento real de éstas, ya que están basada en hipótesis. Hay que tener en cuenta también que hay mucha diversidad animal en el fondo marino, y cada grupo tendrá unas u otras formas de conllevar las condiciones extremas que existen ahí abajo. Además, no he profundizado demasiado en cada tema con el fin de mantener el post ligero y digerible.

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Firstly, why we or any other terrestrial mammal can't survive under the pressure exerted by a column of water?

The hydrostatic pressure can be enormous; it increases about one atmosphere for every 10 meters of water depth. The maximum depth recorded is 10,790m in the Mariana Trench. At this depth, the pressure is 1,100 times greater than the one at the surface.

We have cavities filled with air (nostrils, ears, blood vessels, lungs...). Gases can be compressed, their volume is easily modified. When you dive to the bottom of a deep swimming pool or the sea, you might start getting a painful or unpleasant feeling in your ears and sinuses. that feeling comes from the air sacs in your body being squashed by the pressure of the water.

At great depth, the pressure compresses the gases strongly, leading to the crushing of the surrounding structures, irreversibly damaging them.

So, what do marine animals do to combat this?

Out with the cavities that can be filled with gases. In its place, their bodies are filled with water mostly, because liquids cannot be compressed- or at least not as easily as gases, and its volume is hard to change. For this same reason, deep-sea fish don’t have a swim bladder either (a large organ with air in it, which helps surface fish float up or sink down in the water).

Small and flaccid bodies: Their bodies are usually small and limp, as well as their skeletal structures (ductile bones). Think of a stress ball and a random ball; under enough pressure the normal ball will probably break, while the stress ball modifies its shape to fit the strength of your squeeze. The small structure of their skeleton also allows them to avoid any holes that could hold air.

Another advantage of a small body is that provides little body surface area, which allows the pressure of the water in the inside to be in equilibrium with the pressure of the water in the environment (remember we mentioned deep-sea fish are filled with more water instead of air).

However, having no air cavities and a small body will only get you so…deep?

At the cytological and chemical level, we find some interesting adaptations:

Lipid bilayer: the cell membrane contains fats. In the case of animals, it’s usually made up of saturated fatty acids (solid at room temperature), while that of vegetables is unsaturated fatty acids (liquid). Whenever or not they are saturated will determinate the fluidity and permeability of the membrane, which influences its structure and its charges.

Fluidity also depends on temperature. Let’s not forget that pressure it’s not the only extreme condition down there; the temperature oscillates between 4ºC and 1ºC. Deep-sea animals increase their percentage of unsaturated fatty acids, because these remain liquid at low temperatures (fundamental for proper cell functionality) and keep the membranes loose.

Proteins: to function properly, proteins must be able to change their size and shape, as they usually become larger. This becomes difficult under pressure, as Jeffrey Drazen explains: "A simple analogy is blowing up a balloon. It's easy in air, but try doing it at the bottom of a swimming pool." Thus, pressure has a paralyzing effect on proteins, denaturing them by penetration of water into the hydrophobic interior of the protein.

To prevent this, deep-sea animals collect piezolytes in their cells, organic molecules that bind tightly to water molecules, giving the proteins more space and preventing water from entering the interior of the proteins. The deeper we dive, the more piezolytes tend to be accumulated on cells.

The piezolyte par excellence –due to its universal presence in fish- is the trimethylamine-oxide (TMAO), also responsible for the characteristic smell of fish.

Elasmobranchii, have a large amount of urea in their blood, an organic compound that is toxic. TMAO not only stabilizes proteins but it also neutralizes the harmful effects of urea. The thing is, pressure can cause molecules to be more or less toxic. For this reason, deep-sea sharks accumulate more TMAO than their cousins.

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These are some of the many adaptations that exist, although it’s all based on hypotheses and nothing is proved 100%. It must also be taken into account that there is a lot of animal diversity on the seabed, and each group will have one way or another to deal with the extreme conditions that exist down there. Plus, I haven’t delved too much into each topic in order to keep it light and digestible.

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Primeiro, por que não podemos nós (ou qualquer outro mamífero terrestre) sobreviver à pressão exercida pela coluna de água?

A pressão hidrostática pode se tornar enorme, a cada 10 metros que a profundidade aumenta, a pressão aumenta em 1 atmosfera. A profundidade máxima registrada é de 10.790m na Fossa das Marianas, nessa profundidade a pressão é 1.100 vezes maior que a experimentada na superfície.

Temos cavidades com ar (narinas, ouvidos, vasos sanguíneos, pulmões ...) e os gases podem ser comprimidos, o seu volume é facilmente modificável. Em grande profundidade, a pressão comprime fortemente os gases, levando ao colapso das estruturas circundantes, danificando-as irreversivelmente.

Então, que fazem os animais marinos para combater isso?

Fora as cavidades que podem acumular ar. Em vez disso, seus corpos são principalmente água, porque os líquidos não podem ser comprimidos - ou pelo menos não tão facilmente quanto os gases, e custa muito mais mudar seu volume. Por essa razão, os peixes de águas profundas não têm bexiga natatória (um grande órgão com ar dentro dela, que permite que os peixes que estão na superfície flutuem ou afundem na água).

Corpos pequenos: Seus corpos geralmente são moles, com estruturas esqueléticas pequenas e suaves (ossos dúcteis). Pense em uma bola anti estresse; é macio e quando você aperta facilmente modifica sua forma, mas se a bola for dura, você pode até quebrá-la. Isso também permite que eles não tenham nenhum tipo de espaços vazios no interior que podem ser preenchidos com gás.

O fato de serem pequenos proporciona pouca área de superfície corporal, o que permite que a pressão da água no seu interior esteja em equilíbrio com a pressão da água no ambiente.

No nível citológico e químico, encontramos algumas adaptações interesantes:

Bicamada lipídica: a membrana celular é graxa e, no caso dos animais, é composta por ácidos graxos saturados, enquanto a dos vegetais é composta por ácidos graxos insaturados. O fato de estarem saturados ou não influencia a fluidez da membrana e sua permeabilidade, que influencia a estrutura da membrana e, portanto, a interação das cargas.

A fluidez da membrana também depende da temperatura, e não esqueçamos que a pressão não é a única condição extrema que encontramos por lá; a temperatura oscila entre 4ºC e 1ºC. Animais de águas profundas aumentam sua porcentagem de ácidos graxos insaturados, pois estes permanecem líquidos em baixas temperaturas (essenciais para o bom funcionamento da célula) e mantêm a membrana elástica. Para ilustrar, imagine, por exemplo, um pedaço de banha (graxa saturada) na água e agora azeite (graxa insaturada) na água. O azeite é mais fluido e, sob pressão, pode se mover melhor do que a banha.

Proteínas: para funcionarem bem, as proteínas devem ser capazes de mudar de forma e tamanho, já que costumam ter tendência a aumentar de tamanho. Sob pressão, isso é difícil, como explica Jeffrey Drazen; “Uma analogia simple é encher um balão. É fácil fazer no ar, mas tente fazer no fundo de uma piscina”. Assim, a pressão tem um efeito paralisante sobre as proteínas, desnaturando-as quando a água penetra em seu interior hidrofóbico.

Para evitar essa desativação de proteínas, os animais da parte inferior coletam moléculas orgânicas chamadas piezólitos em suas células. Esses piezólitos se ligam fortemente às moléculas de água, dando às proteínas mais espaço e evitando que a água entre no interior das proteínas e as distorça.

Quanto mais profundo, mais piezólitos tendem a acumular células. O piezólito por excelência, dada a sua presença universal nos organismos marinhos, é o óxido de trimetilamina (TMAO), que também é responsável por conferir aos peixes o seu cheiro característico.

Os elesmobrânquios têm uma grande quantidade de uréia no sangue, um composto orgânico que é tóxico. TMAO não só estabiliza proteínas, também neutraliza os efeitos prejudiciais da ureia. A questão é que a pressão pode fazer com que esses tipos de moléculas se tornem mais ou menos tóxicos. Por esse motivo, os tubarões do fundo do mar acumulam mais OTMA que seus primos.

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Esta é uma das muitas adaptações que existem, embora o seu funcionamento real não seja 100% conhecido, uma vez que se baseiam em hipóteses. Devemos também ter em mente que existe uma grande diversidade animal no fundo do mar, e cada grupo terá uma ou outra forma de lidar com as condições extremas que lá existem. Além disso, não me aprofundei muito em cada tópico para manter a postagem leve e digerível.

Quando terei piezólitos para me ajudar com a pressão da vida?

References and images sources

http://biomodel.uah.es/model2/lip/fluidez.htm

https://www.sciencedirect.com/science/article/pii/S000634951730810X

http://www.bbc.com/earth/story/20150129-life-at-the-bottom-of-the-ocean

https://pubs.acs.org/doi/10.1021/acs.jpcb.0c03319

https://www.animalescuriosos.com/pulpo-dumbo/

https://www.businessinsider.es/fotos-criaturas-abisales-terrorificas-cambiaran-forma-ver-oceano-312807

#biology #zoology #animals #marine biology #biodiversity #biochemistry #fishes #deep sea #my post #piezolytes #Youtube

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carnegiemuseumnaturalhistory · 3 years

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Survival of the Fishiest: Astonishing Adaptations of the Aquatic World

by Shelby Wyzykowski

For Charles Darwin, all sorts of species—from birds and large land animals to flowers and tiny invertebrates—captured his interest and encouraged him to explore the great diversity of life. After years of observation and research, he published his famous book On the Origin of Species in 1859. In it, he presented his revolutionary and controversial theory of natural selection, which is also commonly referred to as “survival of the fittest.” His theory suggested that individuals of a species are more likely to survive when they inherit traits from their parents that are best suited for their specific environment. Essentially, beneficial adaptations give an organism the greatest chance to live and carry on its genetic line. This well-known theory is in part rooted in Darwin’s early experiences with and on the ocean. In 1831, he embarked on a five-year journey on the HMS Beagle, serving as their on-board naturalist. As the crew surveyed and mapped the South American coastline, Darwin marveled at the wonder and beauty of the sea, observing and collecting surface plankton as well as theorizing how coral reefs form. Unfortunately, with no photography and limited technology, studying ocean life was difficult even in shallow water. So, in Darwin’s time, little if anything was known about life far beneath the waves. But if he were alive now, Darwin would no doubt delight in all of the incredible underwater discoveries that have been made by modern-day science. And he would more than likely be awestruck by the many amazing adaptations that sea animals employ to survive.

Aquatic Adaptations: Antarctica

Image by Andrea Spallanzani from Pixabay.

When one thinks of an environment in which adaptation is of the utmost necessity, Antarctica may be the first spot that comes to mind. The Southern Ocean, which encircles Antarctica, is an unforgiving and inhospitable place to live. Rotating currents almost completely isolate these waters from the rest of the Earth’s much warmer seas. This keeps temperatures low…it can drop to 28.6 degrees Fahrenheit in the winter! To combat the cold, Antarctic icefish produce and carry special antifreeze proteins in their blood and body fluids. These proteins bind to ice crystals, dividing their crystalline structures and therefore inhibiting crystal growth. Without this antifreeze, microscopic ice crystals would form in their bodies, severing nerves and damaging tissues to a deadly degree. It’s an incredible adaptation, but it did not happen quickly. About 25 million years ago, the Southern Ocean, flowing around the isolated Antarctic continent, began to cool. Aquatic life in this area had to evolve the special antifreeze proteins, find some other way to adapt to the cold, or go extinct. Today, thanks to their special cold-water adaptation, icefish make up more than 90 percent of all fish species in the Antarctic!

Aquatic Adaptations: Mariana Trench

But Antarctica is not the only harsh environment that demands extreme adaptations. You’d be hard-pressed to find living conditions that are more punishing and severe than in the Mariana Trench. Located in the western Pacific, it is considered to be the deepest part of the ocean anywhere on Earth. Near the trench’s bottom, the lunar-like landscape is pitch-black, and the pressure of the freezing cold waters would instantly kill any land animal. But, amazingly, sea animals have found remarkable ways to thrive.

In most places in the trench, the temperatures are between 34 and 39 degrees Fahrenheit. This extreme cold would not be good for most animals’ bodies because it would damage their cell membranes. These membranes are of a fatty consistency and must stay liquid to function properly. The Mariana Trench’s frigid temperatures would make the fat in a land creature’s cell membranes solid like butter. But deep-sea animals have evolved in a unique way that enables them to avoid such a chilly catastrophe. They have lots of unsaturated fats in their membranes, and these kinds of fats remain liquid at low temperatures and keep their membranes loose and intact.

Besides the bone-chilling temperatures, these aquatic creatures must contend with the pulverizing pressure. Extreme pressure can have a devastating effect on a body’s proteins (these are the molecules that do much of the work in a cell). To keep their proteins healthy and working well, sea life collect tiny organic molecules called piezolytes in their cells. These piezolytes prevent water from distorting and damaging the proteins. The deeper in the ocean an animal lives, the more piezolytes they need to have in their cells. One type of piezolyte, called TMAO (Trimethlyamine-oxide), gives fish their “fishy” taste and smell. Since TMAO increases with depth, being “fishier” is crucial for survival in the deep-ocean environment!

But food is also crucial for the survival of any organism; how is it possible to hunt in a world of darkness? Sea life have found many ways to deal with the lack of light. The stout blacksmelt, for example, has giant eyes that can capture the faintest glimmer of fleeting prey. The tripod fish has such unreliable vision that it mainly relies on sensors in its pectoral fins to detect the movement of a potential meal. And the anglerfish actually emits its own light by a process known as bioluminescence. The light from their built-in “headlight” will actually attract the prey to them!

Aquatic Adaptations Near the Ocean's Surface

Marine life that live a bit closer to the ocean’s surface have also developed ingenious ways to search for food. The Great White Shark could very well be thought of as the bloodhound of the sea. Its sense of smell is so good that it can detect one drop of blood in ten billion drops of water! But, if the prey is close enough, it need not spill one drop of blood for the Great White to detect its presence. This is because these sharks are experts in electroreception, which is the ability to detect weak electric fields in water. Unlike in air, the ability to conduct electricity in water is extremely easy. This scientific fact allows many underwater species, including Great Whites, to sense the weak electrical fields of biological sources (such as their prey). These sharks are known to react to charges of one millionth of a volt (for reference, a tiny AA battery has a mere 1.5 volts of stored energy). This acute sensitivity to electrical fields can be traced to electroreceptors in the shark’s skin. Pore openings peppered over its head receive minute electrical signals from the water and channel these signals into tubes of highly-conductive gel. Each tube ends in a bulb known as an ampulla of Lorenzini. Sensory nerves are activated in the ampulla and send the message to the shark’s brain. Their electrosensitivity is so precise that they can detect prey hiding in the sand bottom!

With such an extraordinary adaptation, Great Whites can be a formidable and terrifying predator. But sometimes even the hunter can become the hunted. If a Great White is foolish enough to go after a sick or young Bottlenose Dolphin, they might find themselves biting off more than they can chew. Living in groups called pods, dolphins have tightly-knit family groups with complex social structures. They actually have their own cultures and display positive cultural behaviors such as compassion and cooperation. So when one member of a pod is targeted as prey, the others will come to its defense and work in a coordinated effort to combat the Great White. They’ll surround the shark and attack it relentlessly. Some use their sturdy, bony snouts like battering rams and slam into the shark’s underbelly and gills, causing massive internal injuries. If the shark is lucky enough, it can make a quick escape, but pods have been known to actually kill sharks. These incidents involving selflessness and cooperation have also crossed the species barrier from time to time when pods of altruistic dolphins have come to the rescue of humans in distress. There have been many reported cases of dolphins encircling and protecting swimmers as they work to successfully fend off a shark’s persistent advances.

The altruistic and cooperative behaviors of dolphins are adaptations that exemplify the true meaning of Charles Darwin’s theory of natural selection. Believing that compassion was the key to evolutionary success, Darwin was in fact frustrated with the way many readers misinterpreted the phrase “survival of the fittest” (a term that he himself did not even coin…biologist Herbert Spencer did so in 1864). This phrase implies the use of selfishness, ruthlessness, and callousness to ensure survival. There’s certainly no denying that these actions have definitely played a part in evolution and in the realities of life. But Darwin chose to believe that sympathy, benevolence, and cooperation played even greater roles in the survival, flourishing, and evolution of a species. In the end, it’s the positive adaptive traits that determine as well as define the overall success of life on Earth.

Shelby Wyzykowski is a Gallery Experience Presenter in CMNH’s Life Long Learning Department. Museum staff, volunteers, and interns are encouraged to blog about their unique experiences and knowledge gained from working at the museum.

#Carnegie Museum of Natural History #Marine Life #Antarctica #Mariana Trench #Great White Shark

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therealvinelle · 3 years

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Vampires in the deep ocean

A conversation with @theoriginalcarnivorousmuffin went some deep and dark places (pun intended), now Twilight tumblr gets a very nerdy post.

Can vampires voyage to the ocean floor, or would the pressure be too much?

(Before we go any further: yes, I know that Edward in Midnight Sun thinks about the good times he’s had moping on the sea floor. However, he never specified depth, so for all we know he could have just gone 60 meters and called it a day. I’m interested in the deep ocean, as in 2000 meters and below.)

To find out, I decided to look up how deepwater fish survive at extreme depths.

According to this paper, it’s because they have evolved not to contain air in their bodies.

Creatures who live at great depths do not have air in their bodies such as the swim bladders found in fish that live in more shallow waters. Without air in their bodies, the pressure problem is solved. Fish, crab, octopus, worms, limpets and clams are just some of the creatures found in the depths of the oceans.

I wanted more information than that, though, before I made any conclusions. I found this article, which posited that there are two known factors allowing fish to survive at extreme ocean depths:

The lack of air. Underwater fish don’t have lungs at all, while diving species (such as the sperm whale) have collapsible lungs

Piezolytes, little organic molecules that stabilize proteins from succumbing to hydrostatic pressure, ensuring they won’t collapse (more on those here). In other words, keeps cells from being crushed.

Potential third factors which remain undiscovered - it’s difficult to properly research deepwater fish, as most die when brought to the surface.

So, the first condition is easily fulfilled. Vampires don’t rely on air, and could fill their lungs with water. Unpleasant but doable. They are now a diving species.

The second condition is more interesting. Little is known of piezolytes, they are a recent discovery. However, I’m going to posit that venom covers this bit. It heals the injures of affected humans, and it heals wounded vampires (you can stick a leg back on and it’ll reattach itself). There’s also Joham and Edward’s ability to impregnate women, meaning sperm has been produced. Vampires are living organism, and venom has a healing quality.

As a vampire goes deep diving, I therefore posit three alternatives: 1, the solved oxygen issue means they're fine. 2, the venom would constantly heal them in a loop, not quite piezolytes but allowing the same effect. 3, the venom heals them upon their return to the surface.

My guess is number 2.

So I say yes, vampires can deep dive. It might not be very pleasant for them, at least not if they go to the bottom of a trench, but they should survive.

Semi-relevant xkcd (Alright, so not relevant at all, but it’s really cool).

Now, when it comes to vampires in space, that’s a different matter. I do believe they’re aliens, which has very interesting implications, but just because they found an agreeable climate on Earth, doesn’t mean they could survive anywhere. Not as easily, anyhow. And they would not prevail in a black hole nor on the surface of a star.

#twilight #twilight vampires #twilight renaissance #twilight meta #twilight worldbuilding #sort of?#the carnivorous muffin #theoriginalcarnivorousmuffin

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onedaywellgotomars · 7 years

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What are the adaptations required for organisms to live in the Deep-sea?

The Hadalpelagic Zone is found 6,000m under the sea’s surface and stretches to the bottom of the ocean. The deepest part of the ocean is in the Marina trench at a depth of 10,911m. At this depth, the pressure is 123.6MN/m² (MegaNewtons per square metre), there is no light from the surface and the temperature is just above freezing. There are 37 oceanic trenches around the world, but despite the harsh conditions encountered in them, there are still living organisms that reside there.

Light:

Below 1,000m there is no sunlight. Organisms have evolved in different ways to deal with this: some are blind and use senses like smell or touch, which may be enhanced, instead of sight. Others may have very large eyes, so that they can see with what little light there is. Alternatively, organisms may use bioluminescence. Bioluminescence occurs in marine animals when lucerifin is catalysed by luciferase in organs called photophores; this reaction produces oxyluciferen and light. Most light produced in this way is blue-green because blue light travels furthest in water. As there is very little red light in waters that deep, most deep-sea organisms are unable to see red light because there is no evolutionary advantage for it. A notable exception is ‘Loosejaw’ fish (the Malocosteid family), which emit red light that they can use to see prey, but their prey are unaware that they have been seen as they are not sensitive to red light. Bioluminescence can have several different functions which include, but are not limited to, the ones listed below:

They can be used as lures to attract prey, such as those used by Anglerfish.

They can be used for camouflage, so that the underside of the fish looks like faint sunlight. Thus, the fish is hidden from the predators below.

It can be used to confuse predators or prey. For example, some squid use flashes of light to stun prey.

Forward facing photophores can even be used as headlights to see things in the deep.

Temperature:

Briny water freezes at -1.8°C, although if water in deep-sea canyons did freeze, the ice would simply float to the surface. As such, although water in Hadalpelagic zone has a temperature range of -1°C to +4°C (except near hydrothermal vents), it still remains liquid. The organisms living there still have to deal with these cold temperatures, which they do in similar ways to those of arctic marine animals: flexible proteins and membranes which use more unsaturated fats (oil is an unsaturated fat whilst lard is a saturated fat).

Pressure:

High pressures do not compress water very much but they do distort complex biomolecules. This is important because these molecules are necessary for life. Proteins are required for a variety of biological processes, including catalysing reactions such as hydrolysis which is essential for life. If the shape of their active site (the place where the substrate binds) changes, then the substrate specific to the enzyme can no longer bind there, so the enzyme is denatured and is unable to fulfil its role. As such, organisms in the deep-sea have adapted in two ways to counteract the effects of the pressure. One way is that the animals have structures in their proteins and membranes that are pressure-resistant. Not much is known about how this works. Another way is through the use of piezolytes which prevent biomolecules from being distorted by the pressure.

A further way is that the organisms may have the majority of their bodies made up of water. Water is not compressed much, so the animal’s body will not be as affected by the pressure.

Oxygen:

Oxygen dissolves better in cold water than in warm water. Due to the lack of energy of the cooler water, the water molecules take up less space, so the water is denser and thus it sinks. This creates a thermohaline current, which replenishes the oxygen content of the water as it is used up by deep-sea creatures. The oxygen cannot be replenished by photosynthesis as there is no light to do this. Therefore, although there are oxygen rich areas in deep-sea trenches, there are also oxygen bereft areas where there are no thermohaline currents.

Food:

Due to the lack of light for photosynthesis, organisms on the sea-floor are dependent on detritus falling from above or hydrothermal vents for nutrients and energy. Although they may be dependent on what falls from above, those that live on the ocean floor have the advantage over those that swim above them because once something has reached the sea floor it can’t fall any further. However, near hydrothermal vents, communities of organisms can thrive as the nutrients from the vents feed bacteria which in turn support larger organisms.

As the detritus that falls can vary, many Hadal zone dwellers have large mouths in relation to their bodies, so that they can eat whatever food they can find. Their smaller bodies mean that they don’t have to support as much muscle or organ tissue in comparison. Many organisms may also have bacteria inside them which convert chemical energy into biological compounds that the animal can use.

Bibliography:

http://scienceline.ucsb.edu/getkey.php?key=301

http://marinebio.org/oceans/deep/

http://news.bbc.co.uk/1/hi/8426132.stm

http://www.convert-me.com/en/convert/pressure/longtoninsq.html?u=longtoninsq&v=8

http://www.nationalgeographic.org/encyclopedia/ocean/

http://www.seasky.org/deep-sea/ocean-layers.html

http://www.seasky.org/deep-sea/bioluminescence.html

BBC: The Blue Planet: a natural history of the oceans by Andrew Byatt, Alastair Fothergill and Martha Holmes

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