By Vidya Rajan, Columnist, The Times
As the weather warms, we watch bees collecting and hauling fat baskets of pollen back to their hives. Bumblebees, with their improbably large bodies hover on whirring, buzzing wings that seem barely adequate to the purpose of elevating, never mind transporting their bulk. Ants swarm kitchen counters and picnics and carry away remarkably large portions of bounty to their nests. Delicate seedlings push back heavy soil and display their tendrils to the sun, and earthworms all the time seemingly effortlessly burrow through soil that we labored to dig and plant the seeds a few weeks earlier. Watching all this, a question springs to mind: Can we compare the relative strengths described against our own? If so, who is the strongest?
Plants are notorious for their actions to break through soil and masonry. As they grow, they find and wedge their fine rootlets into cracks and grow by the addition of cells to their length and girth, patiently and inexorably pushing the grains apart. Eventually, even buildings and rocks crumble under the sustained and unrelenting pressure. Water comes into it. Root cells are buoyed by internal water pressure. Externally, small amounts of water may leach into the rootlet grooves adding some lubrication to the process of root growth. But plants are not made of muscle and their show of strength is not easily translated into human experiences or timescales and is better classified as a force exerted outwards from the root on the surroundings; note that roots do not pull.
For this reason, I am not going to include plants in the measurement of the feats of strength and we shall set them aside. For this reason, also, I will leave aside also bacteria that immovably stick to surfaces, lichen who glue themselves to rocks so strongly that they cannot be scraped off, protist algae such as kelp who can use their holdfasts to attach themselves to submarine rocks such that even tsunamis may bludgeon but cannot budge them. These are feats of strength of clinging to substrates using sticky substances; their strength can be measured, but in effect we will be measuring the strength of their glue, not the strength of the organism themselves. In the same manner, individual cells cling to each other in our bodies to maintain its integrity, but that strength is that of proteinaceous rivets and glue. That, too, shall be set aside, and to keep it simple, I shall examine only the strengths of animals using their muscles to both pull and push.
First, let’s take some examples of animals who have impressive résumés in this arena. We know earthworms can drill through soil. They have with circular muscles, annuli, that ring their bodies, and long muscles that travel from the front of their body to the rear. Their strength to push through dense soil comes from both their ability to inflate and elongate their bodies to drill and pummel the soil using small bristles called setae for traction. They have no bones, but they have a hydrostatic skeleton called a “coelom” filled with fluid against which their muscles push. But they have another superpower. They tunnel by using their guts as the screw to displace soil by consuming up to three times their body weight per day, and excreting it behind as “casts” [1]. They can burrow down to 6.5 feet down into the soil. If you pooh-pooh that statistic, well, I suggest you try digging that deep.
Animals are renowned for their strength. Before machines with internal combustion engines were available for hauling duties, elephants, oxen, and horses were beasts of burden, pulling and plowing for their human handlers. In addition to formidable body size, elephants can shift almost a ton of material and have prehensile trunks that can perform finer manipulations. Strong dray horses (for whose strength the term horsepower was coined) could raise 33,000 foot-pounds of work in 1 minute. This works out to 330 pounds over 100 feet or 3300 pounds over 10 feet in 1 minute. Oxen are mainstays of family farms. They plow the soil, and their dung is a fertilizer. They have been used since times immemorial for their doughty and stolid, rather than speedy, ability to move goods. Mohandas Karamchand Gandhi of India, the Mahatma, or Great Soul, as he was titled, used to joke that his ox-drawn cart was an “Ox-Ford”. Pulling heavy loads, with their female partners producing milk, was obviously an efficient agricultural investment [2].
Non-domesticated mammals are notorious for their strength and their bites. Bears can eviscerate an animal with the swing of a paw tipped with razor-sharp claws; more significantly they can run at 40 miles an hour and their mass which can go up to 400 lbs. for females, and 700 lbs. for males, can makes them into knife-tipped juggernauts with a bite that exerts a force of over 1,000 psi [3, 4]. That animals have powerful bites is not new, nor is it news. Even so, it is worth remarking that the sagittal crest, a bone shaped like a mohawk haircut, is the bone that is used at attachment sites for the masseter, the muscle that anchors the detachable mandible (lower jaw) to the head. The bigger the footprint of the masseter on the sagittal crest, the more powerful the jaws. Mammals (except humans) and reptiles have this crest; thus, their bite is awesome in power. Scavengers such as hyenas and Tasmanian devils use their powerful jaws to crack bones; big cats, wolves, and crocodilians, to name a few predators need their powerful jaws to clamp on to and bring down prey often larger than themselves.
Even leaf eaters like apes and pandas need to masticate their herbal diets. Extinct hominids like Neandertals and Australopithecus had massive sagittal crests. It was thought that a single frameshift mutation caused the masseter muscle of hominids (later humans) to lose power and mass, but, by this time, humans were cooking food to softness with fire, and hunting using tools; thus, this mutation did not have the debilitating consequences it would have for other predators or scavengers. In increasing bite power terms, humans (125 psi) hyenas (1,100 psi), polar bears (1,200 psi), gorillas (1,300 psi), bull sharks (1,350 psi), jaguars (1,500 psi), and hippos (1,800 psi) stack below the world champions crocodiles. The most powerful crocodilians in bite power order are the American alligator (2,125 psi), the Saltwater crocodile (3,700 psi), and chompiest of all, the Nile crocodile (5,000 psi). Regardless of bite force, hippos are widely considered the more dangerous and aggressive animal of all. Having learned this axiom the hard way, Nile crocodiles typically avoid hippos, but, to the crocodiles’ distress, it seems teething hippos like the texture of the spines on the crocodile and enjoy chewing on their tails, documented at https://youtu.be/S_kq5a-bu4w and http://roaring.earth/hippo-licks-crocodile/.
Insects and their feats of strength are familiar to us. A honeybee weighs a little less than a tenth of a gram and can carry about a quarter of its bodyweight as pollen but up to half its bodyweight in nectar [5]. The difference comes because nectar is carried in the crop, but pollen hangs of the rear legs in corbicula causing drag during flight. The honeybee doesn’t even come close to being recognized as strong insects because insect competition is fierce [6]. Ants can lift and carry weights up 50 times their body weight. The Rhinoceros beetle can lift and carry 850 times its bodyweight. And dung beetles are on top of this heap – one was documented to push balls of dung that weighed 1,141 times its body weight, equivalent to a 150 lb person shifting 80 tons. Other arthropods’ achievements in the domain of shows of strength are also legion. The oribatid mite is a tick which can bite and hold on insanely tight with their jaws, with a force up to 1,184 times their body weight [7]. This is no news to those of us with dogs who’ve pulled ticks off our bodies and found that they’ve held on so tight they actually left their mouthparts in the skin, and we’re left holding their oozing bodies in our shrinking fingers. The mantis shrimp is the champion in the “throwing its weight around” category. It can snap its claws with a force 3000 times its body weight. I wrote about this in an earlier article on vision: they have 16 photopsins compared to our 3, and see shades of color that are beyond our ability to even imagine [7].
As to the ability to endure, there is debate about that too, and most of it is speculation. Tardigrades score high on this resilience index. They can endure heat, cold, anoxic conditions, dehydration, starvation, and immense pressures of up to 6000 atm. The diabolical beetle (Phloeodes diabolicus) can endure being stomped on and run over by automobiles. As for contenders for the title for the ability to endure harsh conditions: these are the denizens of the deepest reaches of the ocean, the trenches, and the hydrothermal vents of the benthic depths. They are extraordinary: sponges, mollusks, crustaceans, and fish, but no plants, survive in these places, living off symbiotic bacteria, and dating back to 440 million years ago, enduring debris raining from above (https://youtu.be/fOGEuhQPKvY) and water column pressures that exceed over 1,000 atmospheric pressure units. This year, life was found literally clinging to the underside of the Filchner-Ronne Ice Shelf in the Antarctic, living in unbelievably harsh conditions of bitter cold and dark. The Perseverance Rover is searching for the signs of life that may have once exists, or may still exist, on Mars. Life has been found in the depths of the Mariana Trench, the 5-mile-deep fissure in the Earth’s crust; in recent years, though, trash, including coke cans and plastic, has been found in those depths. We may find that resilience is the ability to survive being suffocated with trash.
This is how the movie Wall-E begins. It may be our future, and a small, resilient, germinating plant may be our succor. Or maybe that champion of endurance, the cockroach. I’d much rather not find out.
- Sartore, J. Common Earthworm. 2021; Available from: https://www.nationalgeographic.com/animals/invertebrates/c/common-earthworm/.
- @OneKindWorld. Top 10 Strongest Animals in the World | OneKindPlanet Animal Education. 2016; Available from: https://onekindplanet.org/top-10/top-10-list-of-the-worlds-strongest-animals/.
- Service, N.P. Grizzly Bear – Yellowstone National Park (U.S. National Park Service). Available from: https://www.nps.gov/yell/learn/nature/grizzlybear.htm.
- BBC Top 10: Which animals have the strongest bite? Available from: Top 10: Which animals have the strongest bite? – BBC Science Focus Magazine
- Association, M.B.B., Module 6 Honeybee Behaviour examination notes. 2011.
- Chodosh, S. Which animal is the most powerful? 2018; Available from: https://www.popsci.com/most-powerful-animals-ranked/.
- Rajan, V., Inner Nature: Eye see colors, in The Unionville Times. 2018. Available from: Inner Nature: Eye see colors | The Unionville Times
