The Insane Biology of: The Venus Flytrap

in 1875 charles darwin published a book that would go on to shake the scientific community to its core some even claimed that what he published was impossible that it was against the order of nature as willed by god his observations began with a peculiar plant in the south of england he noticed dozens of dead insects or what remained of them adhered to the sticky tentacles of the common sundew plant many plants cause the incidental death of certain insects the horse chestnut for example regularly kills insects that get stuck to its protective sticky film but darwin had a hunch that these insect deaths were no accident he collected specimens and began extensive experimentation to find out if these plants could really be catching these insects on purpose to trap them in order to eat them he fed his plants salts of ammonia egg white various insects and even small chunks of cheese until soon he was able to scientifically describe their digestive systems and prove unequivocally and for the first time that plants can indeed eat meat today there are over 600 species of carnivorous plants known to science darwin's beloved sundew plant is in the adhesive trap category where prey becomes stuck to extremely sticky droplets then there are the pitfall traps like pitcher plants where prey falls into the base and is digested and then there's the suction traps like the water wheel plant where aquatic prey animals get sucked into a one-way trap door but the most iconic of all carnivorous plants are the snap traps like the voracious and enigmatic venus flytrap unsuspecting prey lured by the fly trap's sweet-smelling nectar land in the jaws of the fly trap and quickly find themselves locked behind the teeth of the hungry plant where they are then digested slowly over the course of a week the discovery of these meat-eating plants changed the very idea of what it means to be a carnivore but how and why would plants evolve such a taste for flesh how is it possible for a leafy green to become a deadly predator [Music] venus fly traps are naturally found in only one area in the world in the coastal plains of north and south carolina specifically in one small region 200 kilometers across they are small plants that live in the open understory of their habitat an understory that remains open due to natural fires that burn away the larger shading plants and down here amongst the marshy grass is where their killing commences the trap of the venus flytrap is a leaf with two lobes connected at a hinge on its stalk the lobes sit waiting curved in the open position luring prey insects with sweet smelling nectar if something like a fly spider or beetle lands on or crawls across the gaping jaws it risks touching any of the fly trap's six sensory hairs the hairs that give the plant the signal to snap shut if it touches a single hair the plant won't budge and the insect is safe for now but a deadly timer has begun within the plant a crucial 30 seconds that will determine if the insect lives or dies if the insect touches another sensory hair within the 30-second window the insect is doomed upon the second touch the lobes snap shut faster than the blink of an eye the plant's movement is controlled by an electrical signal created by the hairs when a hair is bent by touch it acts as a lever that stretches the envelopes of cell membranes at its base the stretching causes ion channels to burst open positively charged calcium ions flood out creating an action potential aka an electrical signal that spreads from the hair over the entire flap trap after two action potentials the trap snaps shut the initially concave trap lobes move towards each other and eventually change to a convex state the reason it needs two triggers within a 30 second window is to prevent the plant from closing erroneously and wasting energy for something like a raindrop or a twig but how does a plant know when 30 seconds have passed how does a plant tell time researchers had a hunch that it had to do with the changes in calcium concentrations inside the leaves to test this they genetically modified venous fly traps to emit green fluorescence when calcium ions were present in the leaf cells when the first hair is touched a flood of green overtakes the leaf showing a big presence of calcium ions but as the seconds pass the concentration slowly starts to drop but if a second hair is touched the calcium concentration again increases flooding the leaf with even more green it's only when a certain threshold is reached in the calcium concentration that the trap snaps shut this threshold can only be reached if the two stimuli occur within 30 seconds but the timed triggers are not the only way a venus fly trap ensures it eats only the things it wants if you happen to have a pet venus fly trap you may realize you can trigger two hairs yourself causing it to snap shut this may tempt you to feed it cheese like darwin did with his sundew plants but if you did you'd end up disappointed you could indeed get the fly trap to close on the cheese initially but after a few hours it will reopen rejecting your generous gift that's because the plant requires sustained wiggling within its jaws to fully seal and begin the deadly digesting process this ensures it's using its digestive resources only on hearty insect meals but once a wriggling bug does cause the trap to fully seal it's no longer a mouth but a stomach digestive juices flood into the closed trap the ph drops dramatically and meat digesting enzymes similar to ones in our stomachs start to break down the trapped creature the more the prey fights and wriggles the more digestive enzymes are released if you're a bug the more you struggle the faster you die slowly over the course of a week or so the insect's body is liquefied and the lining of the trap absorbs the nutrients it's an impressive if not a bit unsettling survival strategy and it's hard to look at this small plant and understand how it came to be how do plants make the jump from getting all their nutrients from the soil and the sun to luring and brutally killing living breathing creatures while the venus fly trap does extract some energy from its food like we do what it's really after when it kills prey is not the insect's calorie content but rather it's nitrogen plants need nitrogen in order to successfully carry out photosynthesis as it's a major component of chlorophyll it's also a major component of amino acids the building block of proteins and is needed for general growth and regeneration in the plant without nitrogen a plant will wither and die and this could be a major problem for plants growing where the venus flytrap does that particular area of the carolinas where they live has soil that is extremely acidic and nitrogen deficient but this lack of nutrients is no problem for the venus fly trap which gets between 50 and 75 of its nitrogen from chowing down on insects a similar story is true for the other carnivorous plants pitcher plants for example grow in marshy nutrient poor soil as does the sun do it seems pretty clear then that carnivory evolved in plants to cope with nutrient scarce soils that explains the why but how does a plant evolve from a purely photosynthetic life to a meat-eating one to get to the bottom of this question scientists examined the genomes of three related carnivorous plants the venus fly trap the aquatic waterwheel plant and the sundew plant all of these plants use motion to capture prey and shared a common ancestor about 70 million years ago researchers realized that around this time 70 million years ago these plants common ancestor underwent a whole genome duplication generating a second copy of all of its dna this duplication enabled the plants to keep one copy of each gene with the original function the second copy was thus freed up to be tinkered with where mutations could be tolerated eventually these additional gene copies could start to mutate in a way to fulfill an entirely new role for example plants typically produce enzymes that break down a polymer called chitin as a defense against fungi but with a duplicated genome carnivorous plants have repurposed the enzyme to digest insect exoskeletons which are also made of chitin typical plants also use their root system to reach for and absorb nutrients underground in carnivorous plants these genes are repurposed for their traps which are now the primary nutrient absorber regular plants also produce sweet nectar to attract pollinators and now carnivorous plants repurpose these nectar genes to line the trap to attract their victims then as the plants evolved to become even better suited to their new niche specific gene families were expanded gene families that create digestive enzymes for example became up-regulated this allowed plants to fine-tune their different carnivorous strategies then once the plants were effectively exploiting their new niche and absorbing nutrients from living prey their traditional leaves and roots were no longer as necessary many genes that were not involved in carnivorous nutrition began to disappear for instance aquatic water wheel plants eventually lost their root system altogether as a result of losing many of these typical plant genes the three plants observed in the study are some of the gene poorest plants to be sequenced to date meaning they have among the smallest genomes ever discovered in plants all carnivorous plants seem to have followed this genetic road map to get to where they are today however surprisingly it was not a genetic event that happened just once in a single common ancestor belonging to all carnivorous plants it's a sequence of events that has happened several times completely independently from one another carnivory in plants has evolved as many as six separate times some carnivorous plants that even look nearly identical turn out to be nowhere close to each other on the evolutionary tree both families of pitcher plants the tropical genus and the north american genus look almost exactly the same and catch prey in the same exact way with their deep slippery pitcher-shaped leaves full of digestive enzymes yet they became carnivorous at separate moments in history on different branches of the tree of life these discoveries reveal something surprising most plants with leaves and roots contain the material necessary to become carnivorous meaning the path to carnivory is open to all plants given the right circumstances in an environment with little nitrogen and with enough time some photosynthetic plants we know today can and likely will evolve into brand new types of predatory meat-eating plants the shapes they take may be similar to the ones that exist now or new forms may come about altogether plants are remarkable at adapting to adverse conditions and only time will tell which plants will eventually be chowing down on their meaty neighbors on this channel i talk a lot about genetics and evolution and point to a lot of phylogenetic trees to me it's literally the coolest thing ever to get a glimpse back in time to understand when different organisms diverged on the tree of life to see the infinitely complex branches spreading and unfolding over time but it's understandable to ask how do scientists know that stuff for years scientists had only comparative anatomy to go on darwin for example could only look at the beaks of finches to observe their differences and to attempt to discern the different birds relatedness and when comparing two organisms that don't even look the same comparing anatomy can't tell you that much about their connectedness so for a long time it was understandable that people looked at the huge array of life on earth and refused to believe it was all related that every living organism on this planet shares a common ancestor but then came the discovery of dna we can now see that all life does look the same at the molecular level meaning that all life shares a genetic language and by comparing genetic information it's possible to quantitatively measure the relatedness of organisms with data darwin couldn't have ever dreamed of and now with complex algorithms and data analysis aided by massive computing power the study of evolution and genetics has never been more exciting this is the field of computational biology a field that uses computer science to reconstruct genomes build phylogenetic trees to look at evolutionary relationships or unlock the complex folded shapes of proteins in my opinion it's the most important field of research happening today and luckily i've been able to get a solid overview of it from the computational biology course on brilliant the online stem learning platform it takes what should be a difficult subject and makes it into a fun colorful and interactive set of lessons and quizzes it's given me a better understanding of how we know for sure that natural selection is a provable phenomenon and gives me even more ammunition to argue against the creationists that always seem to flood my comment section and to take your learning even further brilliant has tons of interactive courses on computer science and math which dare i say are genuinely fun to do the interactivity makes it easy to learn and is something i wish existed when i was in school the new year is a great time for building new healthy habits and there's no better place to channel that energy than with brilliant i've personally been adding a daily computer science fundamentals lesson to my routine after my daily wordle to get started for free visit brilliant.org real science or click on the link in the description and the first 200 people will get 20 off brilliant's annual premium subscription as always thanks for watching and if you're looking for something else to watch right now you can watch our previous video why spider silk is stronger than steel or real engineering's latest video about the reality of carbon taxes you

Channel: Real Science

Views: 660,334

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Id: CAUOhG_c4Go

Length: 16min 11sec (971 seconds)

Published: Sat Jan 29 2022