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Platypus reception - Manger & Pettigrew 1995
Platypus reception - Manger & Pettigrew 1995
Manger & Pettigrew 1995

“The platypus can locate food by sensing the extraordinarily faint electric fields that their animal prey inadvertently produce [Gregory, E. 1991. Tuned-in , turned-on platypus. Natural History 99 (May):30-37],” writes John Alcock in Animal Behavior: An Evolutionary Approach. “Certain electric fish take this skill one step further by producing a weak electric field and then detecting disturbances to the field caused by a prey’s intrusion into it [Lissman, H. W. 1963. Electric location by fishes. Scientific American 208 (Mar):50 59].” 1

National Geographic Wild presents a short documentary in World’s Deadliest about the Platypus and the Australian animal’s unique view into the electromagnetic world:

Underwater, this ungainly creature has a “sixth sense” that is hard to beat. Australia’s platypus has the tail of a beaver, webbed feet,i and a bill like a duck. But this is no ordinary bill: it is a supersensory organ laden with thousands of cells responsive to the electric fields generated by all living things. So to hunt, the platypus closes its eyes, its ears and its nose, and lets its bill do the work. Called electrolocation, it is thought the waving back and forth motion…helps the platypus to locate exactly where the electric pulses are coming from.2

“Platypuses recognize electric potentials in a highly directional manner as opposed to electric fish that can only migrate linearly to the electric source,” notes Meera Patel for Reed College:

The stripes found on the bill deliver messages through approximately 40,000 electroreceptors and 60,000 mechanoreceptors, creating bimodal input that can predict prey time-of-arrival by interpreting the time difference between the electric and mechanical waves (Pettigrew 1999). The stripes on the bill point to the direction that pray is located. Due to the large surface area of the bill, the receptors allow the platypus to create a local map with field lines that determine the location of prey. In fact, platypuses can respond to electric fields as low as 20mV per cm in a highly directional manner.3

Discovery’s North America program presents a short documentary featuring a fox using the Earth’s magnetic field “to catch a critter under three feet of snow”:

He’s homing in on something. But it takes immense concentration, and he needs complete quiet. His ears can pick up the faintest scamper from beneath the snow. But there’s a catch. He almost always comes up empty handed unless he’s facing north.… Scientists now think he’s actually homing into the magnetic field of the planet using it to calculate and plot his trajectory, the kind of math missiles use to hit their targets.4

Aristotle's five senses
Aristotle’s five senses

“There are at least nine senses and most researchers think there are more like twenty-one or so,” notes Daven Hiskey for the Today I Found Out website:

The commonly held definition of a “sense” is “any system that consists of a group of sensory cell types that respond to a specific physical phenomenon and that corresponds to a particular group of regions within the brain where the signals are received and interpreted [and] are as follows:

    • Wavelengths featuring visible light
    • Sight: This technically is two senses given the two distinct types of receptors present, one for color (cones) and one for brightness (rods).
    • Taste: This is sometimes argued to be five senses by itself due to the differing types of taste receptors (sweet, salty, sour, bitter, and umami), but generally is just referred to as one sense…based off of a chemical reaction.
    • Touch: This has been found to be distinct from pressure, temperature, pain, and even itch sensors.
    • Pressure: [Weight applied to the body by air, water, or some other pressing item.]
    • Itch: Surprisingly, this is a distinct sensor system from other touch-related senses.
    • Thermoception: Ability to sense heat and cold…is a completely different type of thermoceptor, in terms of the mechanism for detection, in the brain. These thermoceptors in the brain are used for monitoring internal body temperature.
    • Longitudinal soundwave diagram
    • Sound: Detecting vibrations along some medium, such as air or water that is in contact with your ear drums.
    • Smell: Yet another of the sensors that work off of a chemical reaction. This sense combines with taste to produce flavors.
    • Proprioception: This sense gives you the ability to tell where your body parts are, relative to other body parts.…
    • Tension Sensors: These are found in such places as your muscles and allow the brain the ability to monitor muscle tension.
    • Nociception: In a word, pain. This was once thought to simply be the result of overloading other senses, such as “touch”, but this has been found not to be the case and instead, it is its own unique sensory system. There are three distinct types of pain receptors: cutaneous (skin), somatic (bones and joints), and visceral (body organs).
    • Human cochlea
    • Equilibrioception: The sense that allows you to keep your balance and sense body movement in terms of acceleration and directional changes. This sense also allows for perceiving gravity.…
    • Stretch Receptors: These are found in such places as the lungs, bladder, stomach, and the gastrointestinal tract. A type of stretch receptor, that senses dilation of blood vessels, is also often involved in headaches.
    • Chemoreceptors: These trigger an area of the medulla in the brain that is involved in detecting blood born hormones and drugs. It also is involved in the vomiting reflex.
    • Thirst: This system more or less allows your body to monitor its hydration level and so your body knows when it should tell you to drink.
    • Hunger: This system allows your body to detect when you need to eat something.
  • Magnetoception: This is the ability to detect magnetic fields, which is principally useful in providing a sense of direction when detecting the Earth’s magnetic field. Unlike most birds, humans do not have a strong magnetoception, however, experiments have demonstrated that we do tend to have some sense of magnetic fields. The mechanism for this is not completely understood; it is theorized that this has something to do with deposits of ferric iron in our noses. This would make sense if that is correct as humans who are given magnetic implants have been shown to have a much stronger magnetoception than humans without.
  • Time: This one is debated as no singular mechanism has been found that allows people to perceive time. However, experimental data has conclusively shown humans have a startling accurate sense of time, particularly when younger. The mechanism we use for this seems to be a distributed system involving the cerebral cortex, cerebellum, and basal ganglia. Long term time keeping seems to be monitored by the suprachiasmatic nuclei (responsible for the circadian rhythm). Short term time keeping is handled by other cell systems.5

“Magnetoception (or magnetoreception as it was first referred to in 1972 [M. LINDAUER & H. MARTIN in S. R. Galler et al. Animal Orientation & Navigation 559/1]) is a sense which allows an organism to detect a magnetic field to perceive direction, altitude or location,” according to Wikipedia.6

“Several mammalian species spontaneously align their body axis with respect to the Earth’s magnetic field (MF) lines in diverse behavioral contexts,” report Vlastimil Hart et al:

Magnetic alignment, i.e., spontaneous alignment of the body with respect to the magnetic field lines, when other determinants (e.g. wind direction, sun position, curiosity) of the body position are negligible, has been demonstrated in several species of mammals in diverse behavioral contexts: in grazing and resting cattle, roe deer and red deer and hunting red foxes as well as in several other mammalian species (under preparation).…

Dogs preferred to excrete with the body being aligned along the North–South axis under calm MF conditions. This directional behavior was abolished under unstable MF. The best predictor of the behavioral switch was the rate of change in declination, i.e., polar orientation of the MF.7

“A study of Google Earth satellite images has revealed that herds of cattle tend to face in the north-south direction of Earth’s magnetic lines,” writes Jeremy Hsu, for the website. “Google Earth is perfect for this kind of research, because the animals are undisturbed by the observer,” said Sabine Begall, a zoologist at the University of Duisburg-Essen in Germany and coauthor on the study detailed in the journal Proceedings of the National Academy of Sciences.8

“A large variety of animals possess a magnetic sense,” notes the Theoretical and Computational Biophysics Group:

Migratory birds use magnetic clues (in addition to light polarization, star signs, position of the sun) to find their way south in fall and north in spring. Salamanders, frogs, use the magnetic field for orientation when they have to find the direction of the nearest shore quickly, e.g., when they sense danger.” 9

“Studies have shown that sea turtles use Earth’s magnetic field to help guide them at sea,” writes Laura Geggel, “but it was unclear whether magnetic features also help steer them toward the nesting sites chosen by their mothers”:

For more than 50 years, scientists have been mystified by how sea turtles do this, said the study’s lead researcher, J. Roger Brothers, a graduate student of biology at the University of North Carolina at Chapel Hill.

“Our results provide evidence that turtles imprint on the unique magnetic field of their natal beach as hatchlings, and then use this information to return as adults,” Brothers said in a statement.…

“We reasoned that if turtles use the magnetic field to find their natal beaches, then naturally occurring changes in the Earth’s field might influence where turtles nest,” Brothers said.

A look at the data, from 1993 to 2011, confirmed this idea. At certain times in some places, Earth’s magnetic field shifted so that magnetic signals from nearby beaches moved closer together. During these times, turtle nests densely covered these areas, they found.

Similarly, there were fewer turtle nests, and the nests were farther apart, in places where magnetic signatures diverged, just as the researchers predicted.10

“Many humans are able to unconsciously detect changes in Earth-strength magnetic fields, according to scientists at Caltech and the University of Tokyo.”

The study, led by geoscientist Joseph Kirschvink (BS, MS ’75) and neuroscientist Shin Shimojo at Caltech as well as neuroengineer Ayu Matani at the University of Tokyo, offers experimental evidence that human brain waves respond to controlled changes in Earth-strength magnetic fields. Kirschvink and Shimojo say this is the first concrete evidence of a new human sense: magnetoreception.11

whale echolocation

“Echolocation is the use of sound waves and echoes to determine where objects are in space,” writes Arizona State University. “Bats use echolocation to navigate and find food in the dark.” 12

“Daniel Kish is infamous for his abilities to see using sound despite being totally blind,” writes perceivingacting at YouTube:

The notion of multimodal perception has been long promoted by some Gibsonian scientists and is understood via ecological psychology. That we can see – and hear – the shape of objects without using the eyes is understandable using the framework of invariants and invariant information – the same information across different senses: The senses are not the cause…the information is! (The senses are only the material cause, but the information is the formal cause, in Aristotelian terms).13

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i The male platypus has “a sturdy erectile keratin spur on each hind leg…just above the webbed foot, which is connected via a venom duct to a venom (crural) gland lying under the dorsal thigh muscles.” The male platypus aggressively injects venom into his opposition by “erecting the spur, grasping and squeezing the victim between his hind legs, and driving the spurs and venom into the victim’s tissues” (Fenner, P.J., Williamson, J.A., Myers, D. 1992. Platypus envenomation—a painful learning experience. Medical Journal of Austrailia 157: 829-832).

When the platypus contracts his leg muscle, he also contracts the muscle wall of the crural gland, which forces 2-4 mL of venom through the hollow spur and into the victim (Fenner et al., 1992).
– Platypus Facts, Davidson College, at (retrieved: 7 December 2013).

1 John Alcock, Animal Behavior: An Evolutionary Approach, 5th ed. (Massachusetts: Sinauer Associates, Inc., 1993), p. 591.

2 “World’s Deadliest : Platypus Hunts with “Sixth Sense”,” NatGeoWild video at, (retrieved: 6 December 2013). (Show video)

3 Meera Patel, “Platypus Electroreception,” Reed College, Biology 342: Animal Behavior, Fall 2007, at (retrieved: 6 December 2013).

4 “Fox Dives Headfirst Into Snow | North America,” Discovery video at, (retrieved: April 2013). (Show video)

5 David Hiskey, “Humans have a lot more than five senses,” 16 July 2010, at (retrieved: 7 December 2013).

6 Magnetoception, Wikipedia, at (retrieved: 7 December 2013).

7 Vlastimil Hart, Petra Nováková1, Erich Pascal Malkemper, Sabine Begall, Vladimír Hanzal, Miloš Ježek, Tomáš Kušta, Veronika Němcová, Jana Adámková, Kateřina Benediktová, Jaroslav Červený and Hynek Burda, “Dogs are sensitive to small variations of the Earth’s magnetic field,” Zoology 2013, 10:80, 27 December 2013, at (retrieved: 22 March 2014).

8 Jeremy Hsu, “Cows Have Strange Sixth Sense,”, 25 August 2008, at (retrieved: 7 December 2013).

9 The Magnetic Sense of Animals, Theoretical and Computational Biophysics Group, University of Illinois at Urbana-Champaign, at (retrieved: 7 December 2013).

10 Laura Geggel, “Sea Turtles Use Earth’s Magnetic Field to Find Home,” Live Science, 15 January 2015, at (retrieved: 14 February 2015).

11 “Evidence for a Human Geomagnetic Sense,” CalTech, 18 March 2019, at (retrieved 3 September 2019).

12 perceivingacting, “Human echolocation – Daniel Kish, ‘Batman’,”, 5 July 2013, at (retrieved: 5 July 2014).

13 Amanda Flaker, “Quantum Empowerment 101,” Chakra Center, 20 December 2012, at (retrieved: 9 June 2014).

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