In the food chain, plants are termed producers,
as they convert energy
from the sun into food.
Food for the primary consumers, the herbivores,
that only feed on plants as their source of energy.
And then, on the top of the food chain,
there are the carnivores, the secondary consumers,
that eat other animals to obtain their energy.
This feeding relationship seems
to be the basic principle of life on earth.
The more surprising is it,
that one group of plants managed to evolve tools
that allowed them to break away,
from the bottom of food chain
and become carnivores themselves.
they are no longer the food of animals, instead animals became their food.
它们不再是动物们的食物 恰恰相反 动物成了它们的食物
The most iconic of these carnivorous plants is probably the venus flytrap.
But why did they evolve like this? And how exactly
does its unique mechanism of catching prey work?
That’s what we’re going to find out in this episode of facts in motion.
The inner workings of the Venus Flytrap.
Hope you enjoy.
Most carnivorous plants live in swamps and marshes,
with soil so waterlogged they are very poor in essential nutrients
like nitrogen and phosphorus.
So in order to survive in these harsh enviroments,
they evolved mechanisms that allowed them to
trap and digest insects and other small animals
that then provide these plants with the nutrients they
can’t find in the ground.
There are many different kinds of carnivorous plants,
each with its own method of killing.
Pitfall traps use the simplest method.
A vertical tube that fills with water, and
drowns anything that falls into it,
which are sometimes even relatively large animals,
like rats and frogs.
Flypaper traps utilize sticky mucus,
to catch insects that come into contact with it.
And then there are snap traps,
the most advanced of all carnivorous plants.
Today,there are only two species of snap traps,
the venus flytrap and the waterwheel plant.
Basically a venus flytrap that grows underwater
where it captures small aquatic vertabrates and tiny fish.
In the wild, the venus flytrap only lives
in a few small patches of wet pine forest in
north and south Carolina, in the United States.
The plant itself is relatively small,
with only four to seven leaves growing outwards
from a single point on its underground stern.
Each leaf blade consists of two reigons
A flat harsh-head photosynthesis capable petiole,
扁平 锐利 可进行光合作用的叶柄
and the leaf, which is shaped into a pair of lobes
that form the trap.
Each with a set of spines along its brain.
Within the trap, six fine hairs,
three on each side that echos triggers.
A closer study of these plants showed that they evolved
from an ancestral lineage that utilized flypaper traps.
The evolution of a mechanism that
can completely lock in the prey.
There are three important benefits
it allows the plant to catch much bigger animals
that provide great and nutritional value
It prevents theft of the prey by other animals like frogs.
and it allows for a more complete digestion
This mechanism alone what already been .
an amazing feet of evolutionary engieering
But there is more.
On top of that,
a series of adaptations
help the Venus flytraps make this process as energy effeicent as possible,
and even distinguish between living prey and other stimuli.
The frist adaptation is that the trap were only tense up together
when two of the hairs are triggered within about a half minute of each other
this keeps the plant from reacting to false alarms like rain drops
while still catching most of the animals
which are likely to brush more than one hair
Another adaptation are the interlocking sawtooth along the much of leave
Although they look like prison bus
that are suppose to lock prey in
they are actually there to allow animals to escape
while the trap shuts so fast
it believes most animals no chance to react
It doesn’t close all the way at first.
Instead it gives undersize inserts a way to escape.
By sliping through this bines
saving the plant’s the expense of digesting an inefficent meal
Only if the prey keep moving around inside the trap
triggering the hairs at least five more times,
the trap would close completely and begin digestion.
In other safeguard against wasting energy
that allows the venus flytrap to reset,
in case the prey escaped
or something else trigger the trap,
like a falling leaf，for example.
but with no musles on nus,
how can they react like animals？
Although the exact sience behinded
is still not fully understood.
In recent years some progress could be
made discovering this mystery.
Reserchers found that when the trap is in the open state,
the cells on the inside of each lop are blown up with water.
While the cells on the outside
have only litte amount of water in them.
This creates the prssure ambivalence
that foces the lops in the convex shape.
Now when the insect brushes against one of the sensitive
then bending triggers the tiny electronic charge.
The charge that builds up inside the cells of the leaf,
but that is not enough to stimulate the snap just yet.
This electronic charge will gradually decay over the next half minute.
So for the electronic singal to exceed the threshold value and
close the trap in other trigger must occur whitin that timeframe.
If that happens,pause and cell membranes
will open up and water was searched
from the cells on the inside of the leaf to those on the outside
till balance is reached.
This happens so fast
that it causes the leaf to rapidly
flip and shape from convex concave
which closes the trap.
Which is interesting because it makes the whole mechanism
less like opening and closing your hand
and more like cocking catapult.
the prosess that takes the plant a lot of time and energy
Which also explains why the traps need such a long time to reopen,
but once the mechanism set up,
all it takes is someone cutting the rope.
In the food chain, plants are termed producers,