What do we mean we say space-time? Students are often trained to say, without missing a beat, that “space-time” indicates a continuum, the inseparability of space and time, and that the continuum view of space and time represents a key aspect of “Modern Physics.” While this is most certainly not wrong, students often run into trouble when asked to further unpack these statements. In fact, even teachers find it difficult to unpack these statements.
Part of the problem is that our culture does not encourage us to attempt to understand things deeply. Despite the advantages of tech-loaded classrooms (let’s not rehash the points again; there must be a million articles on the internet listing the advantages), we still encourage parroting. In other words, tech has not addressed the parroting problem; it has instead made it easier for us to say the right words to pretend we understand something. What’s worse is we don’t even tend to remember the words we may have used to feign understanding. You ask someone the same question you asked them two weeks earlier, they’ve probably forgotten “the right words” that they’re told constitute the answer.
With this in mind, I just wanted to list a few resources that are easy to read and challenging at the same time. These are also resources schools do not often prescribe (or have no patience for). They benefit novices and experts alike, and they’re generous enough to reward many re-reads.
The ABC of Relativity by Bertrand Russell – This is a phenomenal book; it engages any reader who might be interested, and is a rare example of top notch science communication. https://www.gutenberg.org/ebooks/67104 (You can also find copies in most local libraries.)
The Wiki entry for Electromagnetism – If you, like many, are wondering “what does electromagnetism have to do with space-time?,” then let me first say that that’s a very good question. Wiki entries don’t get enough love. This page – https://en.wikipedia.org/wiki/Introduction_to_electromagnetism – is as good an introductory account as any; the references are all verified, and the hyperlinking is exemplary.
Finally, the Wiki entry on Spacetime itself. If you find some aspects of the explanation in this page difficult to follow, it’s likely that you need to develop a slightly better understanding of electromagnetism, so go back to the link in point 2 if you need to. https://en.wikipedia.org/wiki/Spacetime
In general, if you’re looking for free (truly free, not services that track you across tabs or require sign ups) explainers, Wikipedia will work most of the time. We seem to be forgetting that, so this post is also a shoutout to Wiki for keeping its pages accessible, a stance we don’t appreciate enough.
The aquatic world teems with fascinating life forms, with remarkably unique behaviors and adaptations. The underwater world is especially interesting. This post focuses on the octopus, an animal that stands out not only on account of its appearance, but also its intelligence and behaviors. In particular, we’ll be looking at the animal’s mating rituals.
Octopuses, with their complex nervous systems and remarkable ability for camouflage, partake in intriguing mating rituals. What follows is a brief account of octopus mating, with special focus on their courtship and reproductive strategies.
Sexual Dimorphism: Octopuses exhibit sexual dimorphism. The males are generally smaller and possess specialized reproductive structures. The male octopus possesses a specialized arm called a hectocotylus, used during mating in order to transfer sperm to the female. Colloquially, the hectocotylus is known as the animal’s “sex arm.”
Courtship: Expectedly, octopus mating begins with attraction and courtship. When a male identifies a receptive female, he performs what could be called “courtship displays.” These displays involve changing body patterns, postures, and vibrant colorations; these are the male’s ways of communication attraction to the female.
Transferring Sperm Through the Arm: If the male has succeeded in courting the female, he extends his hectocotylus arm toward her. It is worth noting that this arm is often modified and features unique structures and plays a crucial role in sperm transfer. The male then inserts the arm into the female’s mantle cavity, where packets of sperm–called spermatophores–are deposited. The female stores these spermatophores till she is ready to fertilize her eggs.
Factors Influencing Mating Strategies: The mating strategy is often influenced by factors such as the specie of the octopus involved, the animal’s surroundings, and competition. Some species are monogamous; the monogamous male and female typically form a long-term bond during the mating period. Other species are polygamous; the males mate with multiple females. Interestingly, “sneaker males” are known to employ deceptive tactics to mate with females who might be bonded with other males. These sneaker males mimic the appearance of females to evade detection by dominant males before mating with a female.
One Last Fact: Some species may be polygamous, but octopuses are semelparous: that is, they reproduce only once in their lifetime. After mating, both males and females experience “senescence,” a rapid deterioration of health, resulting in death. This, however, is a reproductive strategy aimed at maximizing the chances of offspring survival.
Every type of animal hasn’t been checked, but most animals sleep.
Do all creatures sleep similarly?
No. Elephants can make do with 2-3 hours of sleep, whereas cats sleep for 15 hours and rats sleep for 20 hours. Unlike one of the sleeping beauty characters, humans sleep the least among primates, but we enjoy the highest REM sleep.
What does sleep depend on?
Sleep depends on brain size, metabolic activity, diets etc.
Is sleep the same throughout the time a creature is sleeping?
No. Some experience greater Rapid Eye Movement (REM) sleep.
What’s the difference between REM and non-REM sleep?
Initially when the heart rate and breathing are slow, followed by a relaxation of muscles, the surrounding world slowly fades. Brain activity is similar to a comatose stage and electrical activity is calm. All this is non REM sleep.
After this comes REM sleep; this is when dreams are mostly experienced and brain waves are quick and furious.
People talk of power naps as refreshing. Although they are, what really helps maintain working memory, attention, decision-making, and visual-motor performance is a good night’s sleep. Chronic sleep shortage leads to a disturbance in circadian rhythms, which in turn increases the risks for obesity, hypertension, heart disease, and immune system dysfunction. Incidentally these have been shown to increase risks of infection, inflammation, and even some types of cancer.
Sleep has many functions. While humans sleep, the body quietly progresses with its growth (releases growth hormone), repairs broken bits, and deeply embeds our memories.
Infants are born with no regular sleep rhythm. Although they start with frequent wakeups for feeding, they eventually settle into long sleep through the night and a couple of naps through the day. As they grow this tends to reduce to a single nap. Eventually the dependence on the nap disappears, and a good night’s sleep suffices. Interestingly, infants have long bouts of REM sleep; perhaps a sign that the developing brain requires it.
How Does Sleep Take Over?
It’s the circadian rhythm which nudges human beings to sleep. As the sun goes down, the eyes pass on the information to the pineal gland. The hormone melatonin is released into the brain, which changes the electrical rhythms, encouraging the brain to sleep. As the sun rises, the eyes again pass on the information to the brain. The melatonin is shut down, and the brain wakes up to a fresh day.
Sleep Disorders
One of the biggest public health problems is sleeplessness, and this is not age-specific. People of all ages face this problem. According to the American Academy of Sleep Medicine, about 30% of people have signs of insomnia.
Sleep disruptions include people who find it hard to fall asleep and stay asleep, those who sleep through the day, people who find it hard to sleep in certain seasons, and those who have sleep apnea. In short, people across the world are finding it harder to fall asleep.
Do the Hadza People Sleep Well?
There was an interesting finding from the sleep studies among the Hadza people of Tanzania, who are hunter gatherers. They follow their old ways, but not to every last detail. Men and women go their separate ways during the day for foraging and hunting. At night, they sleep in groups of 20-30 on straw mats. They also have no electric lights.
The study tracked the sleep patterns of 33 men and women for 20 days. Most of them woke up several times during the night–to smoke, relieve themselves, or to calm crying babies. Throughout the 220 hours of the sleep study, the entire group was asleep only for 18 minutes.
A third of the people in the study were either awake or sleeping lightly throughout the night. The elderly went to bed by 10 PM and were awake early, while the young tended to chat and sleep a little later, leading to waking up later. No one worried or complained about not sleeping well. They just got up and went about their day.
What the Researchers Said
The scientists hypothesized that the group’s asynchronous sleeping kept them vigilant, and therefore safe from dangers. While the elderly slept, the young were awake or sleeping lightly, and when the young slept, the elderly slept light. An evolutionary adaptation of sorts. Everyone in the group was providing security by being semi-alert at some point through the night.
9 Tips to Fall Asleep Quickly
Unless people have a sleep disorder or have major worries, sleep is something everybody should slip into with ease. Here are nine simple steps to get a good night’s sleep:
Sync with your circadian clock. Human beings have naturally slept through darkness, and kept awake during the day. It’s best to follow what has worked for millions of years. Don’t forget to get some sun. Avoid the harsh part of the day.
Maintain a routine. It’s best to get under the covers at roughly the same time everyday. This might sound childish, but it helps with falling and staying asleep.
Avoid cat naps. They are good for cats, but not so good for people on a regular basis. If one cannot do without naps, it’s best to keep them to within 20 mins.
Don’t exercise before bedtime. Exercise helps in regulating sleep, but finish exercising at least 2-3 hours before bedtime.
Say “No” to perk up foods. Coffee, tea, and chocolates are best avoided during the second half of the day.
Keep it cozy. Make sure the space you sleep in is comfortable and cozy. This is a place where you put your guard down and let your mind float.
Don’t overeat. Sleep favors the light-stomached, not those with stuffed stomachs.
Relax. Watching or listening to something relaxing is good to nudge people into sleep. On an aside, listening to a boring book is a great way to fall asleep!
Keep your environment cool. Keeping your surroundings cool helps you fall asleep and also improves the quality of your sleep.
Davy Jones’s Locker is a phrase common among seafarers: it is used to refer to wreckage (and humans) condemned to the bottom of the oceans. If the Australian box jellyfish (sea wasp) stings a human being, the probability of the victim ending up on the ocean floor is quite high. Although they look harmless and wispy, their sting is among the deadliest on the planet on account of the venom they produce. Unbearable pain is followed by shock, which can be followed by drowning or heart failure; all in a few minutes. The lucky ones who survive are left with scarring from the tentacles and severe pain for weeks afterward.
Why Be So Venomous
Jellyfish are ethereal-looking and literally go with the flow of the water. Even as food trends come and go, the ancient, non-harmful jellyfish is still food on the plate for many people. The box jellies are different; they swim and hunt their prey, which typically includes shrimp and fish. They don’t really hunt humans, so why do they produce venom potent enough to kill a human being? Researchers think this might be the wrong question to ask.
A Box Jellyfish Image Credit: Mithril (Wikimedia Commons)
The theory for why its venom is so toxic is as follows: while co-evolving with creatures that could harm the jellyfish easily, the jellyfish needed their venom to work swiftly and potently. Humans, on the other hand, have not particularly evolved alongside, or under the particular threat of, predators that have wanted to overwhelm them with toxins; that’s why humans are susceptible to jellyfish venom.
As preys evolve to develop immunity to their attackers’ venom, the hunters also evolve by upping the toxicity of their venom. This is an arms race, so to say. When preys feel they are not especially under attack from a particular animal, their ability to develop resistance or immunity to the attacking animal’s venom may diminish. Creatures like mice, mongoose, and ground squirrels can survive the bite of a venomous snake because snakes continue to pose an obvious threat to their survival.
Humans have not had to deal with venomous predators on the lookout for human prey; in other words, the human specie has not developed any significant resistance to venoms. It’s unfortunate that venomous creatures that hunt other prey end up killing humans.
Do Poisons Only Kill?
Many antibiotics used by humans to fight bacterial infections are poisonous to the bacteria inside the human being, not to the human being consuming it. One creature’s food–or, in this case, medicine–is another creature’s poison. Even water, which is essential for humans and most species, can cause death when consumed in excess.
In other words, a helpful substance can be toxic under some circumstances. It’s also well documented that certain poisons can heal.
For instance, Botox is a modern drug that is used effectively to treat ailments like migraines, uncontrolled blinking, overactive bladders, and excessive sweating. It also helps with relieving spasms in the food pipe and helps cerebral palsy patients to move better. Botulinum, a toxin found in contaminated food, is also commonly available in soil and dust. Interestingly, Botox is a form of botulinum toxin. Its effectiveness in treatment vis à vis its role as a poison is decided by the quantity used. To put things in perspective, one gram can kill 5.5 people averaging 70 kilos.
The CDC (Center for Disease Control) even lists Botox as a Category A substance as it can be misused as a biological weapon.
Venoms or Toxins that Humans Use
Just as humans have learnt to harness botulinum, here are a few other animal whose venoms can be beneficial to humans if administered correctly:
The Gila Monster The Gila monster (pronounced hee-luh), endemic to the deserts of Mexico and the US, does not hunt often; it only gets hungry three or four times a year. Spending 95% of its life in burrows, the slow creature surfaces to raid eggs from nests, and eat young mammals. Storing its fat in its tail, the lizard can grow up to two feet in length.
The lizard’s venom is a mild neurotoxin, which is delivered through its teeth as it chews. A chemical in its saliva helps the lizard digest its food gradually. Scientists have come up with a synthetic form of the same chemical, which is effective in controlling sugar levels and facilitating weight loss in diabetics.
2. Rattlesnakes Rattlesnakes are large venomous snakes found in the US. Arizona, in particular, is home to thirteen varieties. The snake relies on its heat-sensing facial pits to spot its prey. Although its bite can be dangerous, it is rarely fatal.
The anticoagulating protein in the snake’s venom is used in modern medicine to design drugs to help prevent blood clots.
3. Scorpion Venom Scorpion venom contains an element that helps target cancerous cells without affecting the good cells. This makes it easier for doctors to excise the cancerous cells and save lives.
A synthetic version of the mini-protein in the Deathstalker scorpion from Israel binds to cancerous cells. By attaching a fluorescent dye, researchers create what they call a “molecular flashlight,” which, once bound to the cancerous cells, emits near-infrared light. This helps surgeons spot and excise cancerous cells.
A tsunami is a series of extremely large and often devastating ocean waves typically caused by sudden movements on the ocean floor. Usually, these sudden movements are caused by earthquakes, strong volcanic eruptions, or underwater landslides. Tsunamis are dangerous not only because of their size but also because of their speed. In fact, according to the National Oceanic and Atmospheric Administration (NOAA), tsunamis travel faster than 500 miles per hour (mph) in deep regions of oceans, and some of them can last for several days.
The speed of a tsunami is determined by the depth of the region in which it originates and the regions it travels to. In short, the deeper the water, the faster and more devastating the tsunami. What’s more, it is very difficult to spot a tsunami in deep waters, which makes it all the more dangerous. Nonetheless, tsunamis lose speed as they approach shallow coastal waters. In fact, they can strike land at speeds as low as 20-30 mph. This, however, does not make them any less dangerous. The 2004 Indian Ocean tsunami, widely regarded as the deadliest tsunami in human history, killed and displaced over 150,000 people in 11 countries. The tsunami was caused by a massive earthquake near Sumatra, an Indonesian island.
The 2004 Indian Ocean Tsunami
Famously, National Geographic reported that, according to the U.S. Geological Survey (USGS), the tsunami may have released energy equivalent to the detonation of over 23,000 Little Boys—the nuclear bomb that was dropped on Hiroshima during the Second World War. The massive earthquake occurred on December 26, 2004, and unleashed a series of killer waves that reached the coasts of Africa and Thailand the very same day. The tsunami killed almost 150,000 people—the official death toll—across 11 countries on December 26th itself. Although tsunamis slow down as they approach shorelines, they strike with deadly impact velocity. These killer waves carry large volumes of water and can permanently damage coastlines, as was indeed the case with the 2004 Indian Ocean tsunami. In fact, the tsunami also led to the permanent submersion of entire islands in the Indian Ocean. In addition to human deaths, the tsunami also caused heavy property damage. Remarkably, however, there were very few animal deaths.
Some Characteristics of a Tsunami
Since tsunamis can travel faster than 500 mph in the deep ocean, they can cross entire oceans over the course of a single day! Moreover, tsunamis typically have a wavelength (the distance between successive waves) of over 100 miles in the deep ocean. This explains the interval between waves that strike shorelines.
Although tsunamis lose speed rapidly as they approach coastlines, they grow significantly in height. The killer waves are typically around 10 feet tall when they strike land. On the other hand, they can be more than 100 feet tall if they originate near coastlines.
Last month, we focused on the dangers of high-altitude climbing. This month’s post is about avalanches–another danger specific to icy mountainous regions.
Avalanches occur when a slab of snow overlying a weaker layer of snow is triggered and slides down a steep slope. They are dangerous not only because they tend to gather speed very quickly, but also because they draw in more snow as they accelerate. This rapidly increases their mass and volume. In fact, the rapid acceleration can produce a “gravity current,” formed by a combination of snow and air called “powder snow avalanche.” Expectedly, avalanches are especially common in mountainous terrains. In addition to snow, they also draw in rocks and debris. Snow avalanches are called snowslides, whereas rock or debris avalanches are called rockslides. Snowslides can occur along most inclined slopes, including roofs of buildings. Buildings located in mountainous regions are especially vulnerable to avalanches.
Snowslides occur whenever the pull of gravity exceeds the strength of snow cover. They can also be triggered by human activities such as skiing, group trekking, or driving on weak snowpacks. Strong-rooted trees sometimes serve as anchors and bind snow to sleep slopes, thereby preventing avalanches. However, avalanches can also be forceful enough to uproot even dense vegetation. Avalanches also occur spontaneously sometimes: they may be triggered entirely by the gravitational load on snowpacks. Avalanches in icy mountainous regions tend to sweep up trees too. Interestingly, these avalanches (snowslides) are not classified as rockslides. This is because the latter do not include ice or snow. In addition, rockslides are also more fluid in their flow than snowslides.
Classifying and Studying Avalanches
Notably, avalanches have not been classified into specific categories. In fact, it may not be possible to do. Nonetheless, we can study the following characteristics of avalanches: their size, their impact, their composition, and their triggers. Geologists and meteorologists use graded scales to determine the possibility of avalanches. These scales are based on factors such as the stability of snow and the angle of incline. Any slope with a gradient of more than 30 degrees is typically considered steep and dangerous. Commonly used scales include the North American Avalanche Danger Scale and the European Avalanche Size Table.
Did You Know?
Although this sounds counterintuitive, one of the best ways to prevent snowslides is to repeatedly travel on a snowpack whenever snow accumulates. However, crowding on weak snowpacks also triggers avalanches. This is especially common at altitudes higher than 5000 meters (above sea level). This is why there are restrictions regarding the number of people in climbing expeditions. Avalanches can be triggered if too many people are jammed or stranded on a climbing route. Nonetheless, it is possible to stabilize snow using tractors, snowmobiles, or trucks. These machines are also used to “groom” snow so as to make it suitable for recreational activities.
Beware of the vicious circle, though: you can stabilize snow using these machines, but you may well trigger an avalanche while skiing. The key is to develop the capacity to “read” snow. More interestingly, explosives are also used to prevent avalanches: they are used to trigger small-scale avalanches, which tend to reduce or eliminate imbalances in snowpacks.
Though more people are climbing mountains today, few seem to understand the importance of acclimatization.
High altitude impacts the human body in several ways. Beyond 1,500 meters above sea level, the saturation of oxyhemoglobin in the human body begins to decrease. The higher one goes, the lower the saturation of oxyhemoglobin. This is because air pressure reduces with altitude. However, if properly acclimatized, the human body can function reasonably well up to an altitude of 5,000 meters, but acclimatization doesn’t guarantee safety. Moreover, there are very few human settlements at this altitude. At 5,130 meters above sea level, La Rinconada in Peru is currently the world’s highest settlement.
A view of Kangchenjunga (or K2 – the third highest mountain in the world at 8,586 m) from Gangtok, Sikkim, India Image Credit: Johannes Bahrdt
Very High Altitude and Extreme Altitude
Typically, only mountaineers and well-acclimatized researchers cross the 5,000-meter mark. Classifications such as “very high altitude” (between 3,500 to 5,500 meters) and “extreme altitude” (above 5,500 meters) serve to indicate the level of oxygen in the atmosphere. That is, the higher one goes, lesser the oxygen and greater the risk of death. In fact, mountaineers and meteorologists typically refer to the 8000-meter mark as the “death zone.” This is because the so-called death zone does not contain enough oxygen to sustain human life.
Altitude Sickness, Hypoxia, and Acute Mountain Sickness
But how exactly does high altitude affect the human body? First, the lower air pressure at very high altitudes can directly lead to hypoxia, a severe case of oxygen deprivation. Early symptoms include fatigue and confusion. Since it is normal for climbers to experience some degree of fatigue and confusion at very high altitudes, it is difficult to determine whether fatigue and confusion will necessarily lead to hypoxia. In addition, these are also symptoms of acute mountain sickness, which also occurs due to decreased oxygen and air pressure levels at high altitudes. One of the best ways to alleviate acute mountain sickness is rapid descent. Acute mountain sickness typically occurs when climbers ascend too quickly. Therefore, it is essential for climbers to acclimatize properly to very high altitudes. Typically, climbers spend two or three weeks at base camps to acclimatize for expeditions. Even if one is well-acclimatized, too much physical exertion at very high altitudes can cause acute mountain sickness.
Other symptoms of severe altitude sickness include excessive coughing, painful breathing, skin discoloration, and hallucination. In extreme cases, altitude sickness may require hospitalization. At very high and extreme altitudes, the human body may also experience high-altitude pulmonary edema (HAPE), a fatal accumulation of fluid in the lungs. Excessive coughing, fatigue, and congestion can also be symptoms of HAPE. On the other hand, signs of HAPE include wheezing while breathing, rapid breathing, and rapid heart rate. Since HAPE and acute mountain sickness have similar symptoms, it is best to descend rapidly to avoid fatality.
Interestingly, people who live 2,500 meters above sea level typically tend to adapt to decreased oxygen levels. Compared to newcomers, those who live at these altitudes have greater lung capacity and endurance. Although the human body can adapt to high altitudes, very high and extreme altitudes are extremely punishing.
Molting is a fascinating biological phenomenon practiced mainly, but not only, by invertebrates. It involves the shedding or casting off of a particular part of the animal’s body. Typically, animals shed their epidermis, the outermost skin layer; pelage; or wings. Some arthropods even shed their entire exoskeleton. Indeed, arthropods differ from other invertebrates in that they possess an exoskeleton. Molting is either necessitated by external factors such as climate-related or seasonal changes or occurs at specific points in an animal’s life cycle—that is, when animals outgrow their skin or their exoskeleton, or when they metamorphose into adults.
Some Molting Animals
Cats and dogs (Fur)
Molting is also common among mammals, amphibians, and reptiles. For instance, dogs and cats typically molt fur to adapt to external changes. Cats usually molt fur after winter, especially during spring-summer. Dogs, on the other hand, molt fur owing to changes in the extent and degree of sunlight, and not because of seasonal changes.
Snakes and lizards are perhaps the most famous molting animals. Both animals rely on the contours of their habitat to remove or shed skin: they usually seek out rough edges, objects, or surfaces to facilitate molting. Snakes typically refrain from eating just before a molt; they are also known to seek safer habitats during this period. Molting is essential to a snake’s well-being, as it allows the animal to eliminate harmful parasites and bacteria from its epidermis. Remarkably, snakes sometimes shed their old skin in one piece. Snakeskin, especially when intact, is also a highly valuable commodity.
Lizards, on the other hand, not only practice molting but also consume their own shed skin. Lizard skin, it has been found, is rich in nutrients, especially calcium. What’s more, lizards, much like starfish, also have regenerative capabilities. They can shed their tail at will to escape predators and obstacles, and can regrow a fully functional tail in just about 60-70 days.
Birds (Feathers)
Birds shed feathers fairly regularly, and they do so mainly to replace dead feathers. Unlike lizards and snakes, however, birds do not shed all their feathers at once, since feathers regulate their body temperature and offer them protection. Notably, almost all birds—from hens to vultures—practice molting. In fact, since molting enables hens to lay eggs, hens are widely subjected to forced-molting, an unethical commercial practice aimed at enhancing the capacity of captive hens to produce eggs.
Arthropods (Exoskeleton)
Arthropods (especially insects, spiders, and crustaceans) typically shed their exoskeleton or shell during metamorphosis. Molting is thus not only a necessary process for arthropods but also a transformational one. Arthropods that reach adulthood through metamorphosis are markedly different from their larval selves.
Did You Know?
Molting is also known as sloughing or shedding.
Invertebrate molting is also called “ecdysis,” a term derived from Ancient Greek. Roughly speaking, ecdysis means “to remove” or “to cast away.”
So far, I’ve written about beavers, giraffes, the Venus flytrap, a few other animals, and this month I turn my attention to jellyfish.
Jellyfish are one of the oldest animals on Earth. Interestingly, jellyfish are not really a type of fish; they are invertebrates. In other words, they are aquatic animals that do not have backbones.
Jellyfish are rather ubiquitous. They can be found in abundance in warm as well as cold ocean water. They can also be found in the depths of the oceans and along shallow coastlines. They are also seen in freshwater lakes and ponds.
Scientists have so far discovered more than 2,000 different types of jellyfish. What’s more, it has also been reported that there could be nearly 300,000 more species of jellyfish yet to be discovered. Being invertebrates, jellyfish do not have a skeleton. In addition, most jellyfish have a transparent body, which makes them rather difficult to spot. On the other hand, some jellyfish are quite conspicuous in that they are bright and luminescent.
Jellyfish are notorious for their ability to deliver extremely painful, and sometimes stunning, fatal stings. They capture prey with the help of their tentacles, which are populated with stinging cells. Some jellyfish are also known to feed on other jellyfish, too.
Jellyfish are remarkably simple organisms. They do not have vital organs (such as the brain, heart, and lungs). In fact, contrary to popular belief, they do not have legs, feet, hands, or even eyes and ears. Remember: their tentacles cannot be regarded as limbs.
Despite being a simple organism, some jellyfish can deliver a fatal sting. They propel themselves forward by squirting water through their mouth. In fact, like the hydra—a genus of small, freshwater organisms—jellyfish also dispel waste through their mouth. Although they can propel themselves forward, jellyfish are highly limited swimmers. Too often, their movement is determined by ocean currents and other external factors.
The Jellyfish’s Constitution
Being simple invertebrates, jellyfish are made almost entirely of water (more than 90% according to most scientific accounts). As a result, when jellyfish get stranded along coastlines, they simply evaporate. Nonetheless, they posses a simple yet effective nervous system that allows them to detect light and gauge depth. They are also adept at digesting food quickly.
Even dead jellyfish can deliver a sting when touched or stepped on. However, not all jellyfish are poisonous; some are even edible, whereas others have been found to have medicinal value.
The Venus Flytrap is not the only carnivorous plant. Pitcher plants are also famous for their carnivory, and as their name suggests, these plants possess pitcher-shaped leaves that form a pitfall trap. Much like the flytrap, pitchers typically grow in poor soil and are mainly found in dry pine fields and coastal swamps.
Pitchers attract prey with their pitfall traps, which are filled with nectar. Pitchers kill their prey by drowning them in nectar. In addition, the pitfall traps contain a deep cavity filled with digestive fluids. Pitchers typically attract crawling or foraging insects. Sometimes, they also attract flying insects. Pitfall traps typically become moist and slippery due to condensation, and this enables pitchers to snare unsuspecting prey. Condensation is usually caused by two factors: weather conditions (external factor) and nectar (internal factor).
Their Prey-Trapping Mechanism
Pitchers are known for their elaborate prey-trapping mechanism. They may contain waxy scales, protruding aldehyde crystals, or prey-trapping hairs. Some pitchers may also contain what are called “guard-cell-originating” lunate cells along their insides to ensure that trapped insects remain trapped. Once trapped, pitchers drown their prey to ensure proper digestion. Drowned prey are first dissolved, and pitchers accomplish this by relying either on their own enzymes or internal bacterial action. Interestingly, pitchers do not naturally host digestive bacteria; they do so only inadvertently, and this is mainly because their pitfall traps remain open most of the time. As a result, digestive bacteria are driven into their traps by rainfall, wind, and other external factors. At the same time, it must be noted that not all bacteria that are driven into pitchers facilitate digestion.
What Does Digestion Entail?
As mentioned above, once they lure and drown their prey, pitchers begin to digest their catch. But what exactly does this process entail? Aided by enzymes and digestive bacteria, pitchers convert their catch into a nutritious solution. In essence, this solution is a broken-down form of the mineral nutrition that constitutes their prey. Since pitchers feed mainly on insects, this broken-down solution mainly consists of amino acids, urea, peptides, and phosphates. As one can see, pitchers rely on insects especially for nitrogen and phosphorous. This is because much like most carnivorous plants, pitchers do not rely on photosynthesis for their survival: they draw minerals from the soil and nutrients from their insect prey.
Did You Know?
Pitchers are extremely resilient. It is no surprise, therefore, that, unlike the Venus Flytrap, pitchers face no threat of extinction.
BTW, “Pitcher plants” is an umbrella term: it refers to different species of carnivorous plants that use the pitfall-trap.
Science and Arts Education 