{"id":37863,"date":"2026-04-12T06:00:59","date_gmt":"2026-04-12T10:00:59","guid":{"rendered":"https:\/\/coatesvilletimes.com\/?p=37863"},"modified":"2026-04-08T10:39:00","modified_gmt":"2026-04-08T14:39:00","slug":"inner-nature-making-sense-of-the-senses","status":"publish","type":"post","link":"https:\/\/coatesvilletimes.com\/?p=37863","title":{"rendered":"Inner Nature: Making sense of the senses"},"content":{"rendered":"

By Vidya Rajan<\/strong>, Columnist, The Times<\/em><\/p>\n

\"\"In the brilliant movie adaptation of the potboiler Jurassic Park<\/em> by Michael Crichton,[1]<\/a> there is an early gripping scene where the Tyrannosaurus rex<\/em>\u2019s enormous head is just inches away from the paleontologist-protagonist, who whispers to two children beside him that the predator could not detect them if they stayed perfectly still. I remember my outrage as a biologist \u2013 It was a predator, or at least a scavenger, for heaven\u2019s sake, so what about its ability to smell? To hear? \u2013 but the plot line was that the money-grubbing lawyer was to be eaten and, so, off to the outhouse the T.rex<\/em> went. Vision is just one of many senses engage with the surroundings and respond appropriately, that is, to stay, fight, or flee. Briefly, a \u201csense\u201d is a biological tool that helps reveal information about the opportunities and dangers that an organism faces, and accurately sensing these is pivotal to surviving and thriving. In the following set of articles, I will examine specific senses independently, but in this article, I will describe some basic senses and their function with lighthearted\/anecdotal examples.<\/p>\n

All organisms, including single-celled ones, respond to their internal physiological conditions as well as their external surroundings. Internal sensing can be divided into \u201cinteroception\u201d for physiological factors such as chemical balance and cell volume, proprioception for the relational location of parts of the body, and kinesthetic sense for movement. External sensing, \u201cexteroception\u201d uses a variety of senses: chemoreception (taste) to identify attractive or repulsive chemicals, thermoception for heat and spiciness, mechanoreception for stretch and touch, barometric reception for pressure changes, photoreception for light, echolocation, olfaction (smell, as distinct from taste), electroreception for sensing electrical fields, magnetoreceptors for sensing magnetic fields, nociception for pain, hygrosensation for humidity and, sound reception in hearing. Some of these senses are closely related; for instance, taste and smell are allied, as are temperature receptors with those for pain, and hearing is associated with pressure wave changes which is why you can both hear and feel the thudding of percussion through your feet on a dance floor. Although electromagnetic radiation (EMR) such as magnetic field lines and bioelectricity can be sensed by some animals, most others cannot detect EMR from the Sun, nuclear emissions or machinery, which can impact biological systems but cannot be detected by senses, thus requiring monitoring and exposure safety limits.[2]<\/a>,[3]<\/a><\/sup><\/p>\n

Senses help with communication \u2013 pollinators can find flowers through visual and olfactory cues; long-eared fennec foxes can hear prey moving under desert sand in the dark, sharks can smell faint chemical traces of blood and distress in the water, and many animals sing and dance to signal their openness to mating, including humans. The Guugu Yimithirr people are so attuned to cardinal directions that they have no words for \u201cleft\u201d or \u201cright\u201d. Rather, they say instead, \u201cMove a bit east\u201d.[4]<\/a> Some people claim to have \u201csixth senses\u201d for spooky things like ghosts, or to optimize positive \u201cvibes\u201d through practicing Feng Shui<\/em>, Vaasthu Sastra, <\/em>or Reiki<\/em>. Many nature observers who depend on the weather (historically farmers and sailors) swear by animals\u2019 wisdom: cows lying down means it will rain, animals moving to higher ground means a tsunami is imminent, and famously, Punxsutawney Phil\u2019s shadow (or not) predicting the arrival of spring.<\/p>\n

Organisms that exist as single cells are usually suspended in a fluid environment, and solutes in the water are a measure of that organism\u2019s ability to obtain food, and thereby regulate its growth and reproduction. The exteroception of attractive chemicals such as food and pheromones versus repulsive or toxic ones produce internal signals through molecules which regulate the physiological or genetic output and can guide the cell to accept or reject the substance. Another surprising sense some single-celled organisms have is the ability to sense light, but light has two uses, as a source of energy through photosynthesis, and for vision. Proper vision requires a brain for processing images, but sensing light and dark requires merely a light-absorbing pigment which triggers a mechanism that causes movement. Interoception is important for the cell to recognize its need for food, or for recognizing it is large enough to split into two cells. These are recognized by the state of binding of a key biomolecule such as the energy molecule, ATP, to a sensor molecule. Absence or low concentrations of ATP leave the sensor unoccupied, which could trigger, for example, random cell movement which might help it bump into food, or to deploy more receptors to search for food molecules. Cells also maintain tabs on their own cell size and the presence of abundant food causes them to grow and reach a tipping point where they divide into two, or sometimes more, cells.<\/p>\n

In multicellular organisms, finding food becomes a matter of persuading all the cells of the organism to coordinate actions. Plants stay in one place and grow up towards light and down towards water. Fungi find a living or dead host to grow on and digest. Some animals allow food to come to them, which means they sit and wait for prey, but must accurately sense the prey\u2019s approach using chemicals, vision, noise or pressure changes and unleash rapid trapping or killing motions using grabbing tools such as teeth or tentacles. For animals which pursue their prey, their senses have to be keen enough to detect prey that is either good at camouflage or fast enough to escape being caught. Many \u201cprey\u201d animals have collectivized for the benefits of a group being better at surveillance than a lone individual; this also benefits the predator because they can also collectivize to catch a slow or unfit member of a large group. To do this, they must quickly assess each individual\u2019s fitness and communicate plans with sounds or actions. In response, herd animals such as antelope can signal fitness through dramatic leaps in the air as if to say, \u201cI\u2019m fit and will get away, so find someone else!”<\/p>\n

Recently, the merger of two 30 solar mass black holes from 1.3 billion light years away created gravitational waves \u2013 a sort of pressure wave made up of electromagnetic radiation (photons). Although we do not have the ability to sense at the frequency of these waves, appropriately tuned instruments can help. The single black hole produced a \u201cringdown\u201d – a which was picked up on 14 September 2015 and translated to pressure waves that our auditory senses could interpret. To hear what it sounded like, hit the play button on the LIGO Lab\u2019s video below. The little \u201cchirp\u201d is all we can \u201chear\u201d at our spatial and temporal distance of that release of energy equivalent to 4.3×1037<\/sup> tons of TNT[5]<\/a> or 3 of our Suns exploding simultaneously. Which other life forms sensed it? How long ago, and using which sense?<\/p>\n

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