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A record-breaking pollen catapult. Nature 435:164



The release of stored elastic energy often drives rapid movements in animal systems1, 2, and plant components employing this mechanism should be able to move with similar speed. Here we describe how the flower stamens of the bunchberry dogwood (Cornus canadensis) rely on this principle to catapult pollen into the air as the flower opens explosively3, 4, 5. Our high-speed video observations show that the flower opens in less than 0.5 ms — to our knowledge, the fastest movement so far recorded in a plant.
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Vol. 2801 (eds Banzhaf, W. et al.) 1–9 (Springer, Germany, 2003).
Supplementary information accompanies this communication on
Nature’s website.
Competing financial interests: declared none.
A record-breaking
pollen catapult
he release of stored elastic energy often
drives rapid movements in animal sys-
, and plant components employ-
ing this mechanism should be able to move
with similar speed. Here we describe how
the flower stamens of the bunchberry dog-
wood (Cornus canadensis) rely on this prin-
ciple to catapult pollen into the air as the
flower opens explosively
. Our high-speed
video observations show that the flower
opens in less than 0.5 ms — to our knowl-
edge, the fastest movement so far recorded
in a plant.
Cornus canadensis grows in dense carpets
in the vast spruce-fir forests of the North
American taiga.As bunchberry flowers burst
open, their petals rapidly separate and flip
back to release the stamens (Fig. 1). During
the first 0.3 ms,the stamens accelerate at up to
24,0006,000 m s
(2,400g), reaching the
high speed (3.10.5ms
) necessary to
propel pollen, which is light and rapidly
decelerated by air resistance (terminal velocity,
pollen granules are launched to an impressive
height of 2.5 cm (range, 2.2–2.7 cm; n5),
which is more than ten times the height of
the flower: from this height, they can be car-
ried away by the wind. (For methods and
movies, see supplementary information.)
Petals open independently of stamen
activity, moving out of their way within the
first 0.2 ms (Fig. 1).Petals attain a maximum
speed of 6.70.5ms
, accelerating at up
to 22,0006,000 m s
(or 2,200g). The
process of petal opening and pollen launch
in bunchberry plants occurs faster than the
opening of Impatiens pallida fruits
(2.8–5.8 ms, n3, see supplementary infor-
mation); the snap of venus flytraps (Dionaea
muscipula; 100 ms)
; the leap of froghoppers
(Philaenus spumarius; 0.5–1.0 ms)
; or the
strike of the mantis shrimp (Odontodactylus
scyllarus; 2.7ms)
As in these other organisms
, rapid
movements in bunchberry flowers rely on
stored mechanical energy. Physiological
processes, which take about a millisecond
for each enzymatic reaction
, are not
required for the explosion itself.We find that
the flowers will open even when the stamen
filaments have been crippled by treatment
with sodium azide. But the flowers do not
open if their turgor is reduced: dehydration
of flowers with sucrose decreases the extent
of opening, although subsequent rehydra-
tion allows them to open fully (results not
shown). Turgor pressure is therefore
required in the production of mechanical
energy for explosive flower opening.
Bunchberry stamens are designed like
miniature medieval trebuchets — specialized
catapults that maximize throwing distance
by having the payload (pollen in the anther)
attached to the throwing arm (filament) by a
hinge or flexible strap (thin vascular strand
connecting the anther to the filament tip).
This floral trebuchet enables stamens to pro-
pel pollen upwards faster than would a simple
catapult. After the petals open, the bent fila-
ments unfold,releasing elastic energy. The tip
of the filament follows an arc,but the rotation
of the anther about the filament tip allows it
to accelerate pollen upwards to its maximum
vertical speed, and the pollen is released only
as it starts to accelerate horizontally (Fig.2).
The rapid opening of the self-incom-
bunchberry may enhance cross-
pollination in two ways. First, when insects
trigger flower opening, the pollen released
sticks to their body hairs until it is transferred
to an adhesive stigma. The force required to
open flowers (0.1–0.5 mN) favours large
pollinators (bumblebees, for example) that
move rapidly between inflorescences; it effec-
tively excludes smaller, less mobile visitors
such as ants.Second,pollen from flowers that
open by themselves may be carried by wind
currents. Indoors, pollen is transported over
22 cm (more than 100 times the size of the
flower) and outdoors, in the presence of a
steady wind, pollen can move farther than a
metre. Exploding flowers enhance insect
pollination and may allow wind pollination,
adding to growing evidence that flowers often
use multiple pollination mechanisms
Joan Edwards*, Dwight Whitaker†,
Sarah Klionsky*, Marta J. Laskowski‡
Departments of *Biology and Physics, Williams
College, Williamstown, Massachusetts 01267, USA
Biology Department, Oberlin College, Oberlin,
Ohio 44074, USA
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29, 83–112 (1998).
Supplementary information accompanies this communication on
Nature’s website.
Competing financial interests: declared none.
brief communications
VOL 435
12 MAY 2005
0 ms 0.2 ms 0.4 ms 1.0 ms
Figure 1 Bunchberry flower opening, recorded on video at 10,000 frames per second. Time elapsed is indicated. First frame shows a
closed flower with four petals fused at the tip, restraining the stamens. Blur represents the distance moved in 0.1 ms. Scale bar, 1mm.
Figure 2 Dynamics of floral explosion. a, Coordinates x and y of positions of the filament tip (blue triangles) and anther tip (red circles), plotted
at 0.1-ms intervals. Inset, a single stamen; points used to plot positions are indicated. Arrows, stamen positions just before pollen release.
b, Coordinates x and y of velocity components of the anther (top) and filament (bottom) as a function of time, derived from the first six points
in a. Arrows, velocity just before pollen release. Error bars represent uncertainty in measurements from a, propagated as random errors.
Time (ms)
Velocity (m s
0.5 1.0 1.5
Position x (mm)
Position y (mm)
12.5 brief comms NS 5/5/05 5:47 PM Page 164
© 2005
... The small size of both pollen and spores presents challenges for dispersal (Vogel, 2005a, b; Figures 1 and 2). Both have a low terminal velocity and are rapidly slowed by air, which is advantageous for remaining aloft but means that ballistic propulsion at slow speeds is ineffective (Edwards et al., 2005;Zanatta et al., 2016;Gómez-Noguez et al., 2017). A solution that has evolved multiple times across the plant tree of life is the use of rapid movements to increase acceleration, velocity, and distance traveled (Martone et al., 2010;Edwards et al., 2019). ...
... First, high-speed video has revealed new biomechanical mechanisms of ultrafast motions that were not visible in real-time video. Notable are the characterization of the stamens of Cornus canadensis L. (Cornaceae) as hinged catapults or trebuchets by filming at 10,000 fps (Edwards et al., 2005), the visualization of the spore-dispersing vortex rings from the exploding capsules of Sphagnum moss by filming at 100,000 fps (Whitaker and Edwards, 2010), the three stages of catapulting spores from the leptosporangia of ferns including a built-in brake system by filming at up to 125,000 fps (Noblin et al., 2012;Poppinga et al., 2015;Llorens et al., 2016), and the dispersal of multiple gemmae from a single droplet hitting a gemmae cup of Marchantia by filming at 3000 fps (Edwards et al., 2019). Second, high-speed videos of falling spores have provided more precise measures of terminal velocity, acceleration, or falling rates of spores, which when compared, may provide insight on the evolution of the diversity of spore and pollen sizes and impact of ornamentation patterns. ...
... Some examples of the diversity in size, shape, and ornamentation of gametophyte diaspores are given in Figures 1 and 2. Zanatta et al. (2016) and Gómez-Noguez et al. (2017) link differences in size to terminal velocities for ferns and mosses. Examples of acceleration measurements include the catapult stamens of male flowers of Morus alba L. (Moraceae), which straighten in 25 µs (Taylor et al., 2006), or the astounding acceleration achieved by the stamens of Cornus canadensis, which accelerate at up to 24,000 m·s −2 (Edwards et al., 2005; Video 1). ...
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Dispersal of gametophytes is critical for land plant survivorship and reproduction. It defines potential colonization and geographical distribution as well as genetic mixing and evolution. C. T. Ingold's classic works on Spore Discharge in Land Plants and Spore Liberation review mechanisms for spore release and dispersal based on real‐time observations, basic histology, and light microscopy. Many mechanisms underlying spore liberation are explosive and have evolved independently multiple times. These mechanisms involve physiological processes such as water gain and loss, coupled with structural features using different plant tissues. Here we review how high‐speed video and analyses of ultrastructure have defined new biomechanical mechanisms for the dispersal of gametophytes through the dissemination of haploid diaspores, including spores, pollen, and asexual reproductive propagules. This comparative review highlights the diversity and importance of rapid movements in plants for dispersing gametophytes and considerations for using combinations of high‐speed video methods and microscopic techniques to understand these dispersal movements. A deeper understanding of these mechanisms is crucial not only for understanding gametophyte ecology but also for applied engineering and biomimetic applications used in human technologies.
... Plant tissues achieve striking, forceful movement driven by fluid flow rather than muscle. [1][2][3][4] Often it is the tissue's ability to maintain an internal hydrostatic pressure above atmospheric levels, also known as turgor pressure, that enables the strength of these motions. By these means, plants resist gravity, penetrate soil, and overcome energetic barriers to leverage instability. ...
... A UMAT is used to incorporate a Gent constitutive behavior as the material property. 3 A limiting stretch (J lim ) of 5, corresponding to the sti↵est PDMS formulation in our experiments, is chosen for the Gent model. Approximately 50,000 hybrid, second-order, tetrahedral elements (C3D10H) comprise the continuous solid matrix and the cavity is modeled using the 'fluid-filled cavity' feature of ABAQUS. ...
Even without the aid of muscle, plant tissue drives large, forceful motion via osmosis-driven fluid flow. Hydrogels are well-known synthetic materials that mimic this osmotic mechanism to achieve large swelling deformations. However, hydrogels can be limited by a loss of stiffness as their swelling increases. Here we demonstrate that a synthetic plant tissue analog (PTA) can mimic the closed-cell structure and osmotic actuation of non-vascular plant tissue, enabling the emergence of turgor-pressure-induced stiffness and leading to more forceful swelling deformations. PTAs consist of micrometer-sized saltwater droplets embedded within thin, highly stretchable, selectively permeable polydimethylsiloxane (PDMS) walls. When immersed in water, PTAs reach a state of equilibrium governed by the initial osmolyte concentration (higher produces more swelling) and cell wall mechanical response (stiffer and less stretchable yields less swelling). Given these behaviors, PTAs represent an alternate class of aqueous, autonomous synthetic materials that, like hydrogels, may benefit biomedical applications.
... The term ballistic pollen dispersal has been used for pollen release in Synaphea (Ye et al. 2012) and for many other taxa such as Cornus canadensis (Cornaceae, Edwards et al. 2005). Edwards et al. (2005) specifically describe the method of pollen release as being similar to a miniature trebuchet. A trebuchet uses a lever system to propel a projectile over a distance and has a particular aim-to hit a particular target, however, in the case of Synaphea, C. canadensis and other taxa such as Desmodium (Fabaceae, Aleman et al. 2014), Urtica and Parietaria (Urticaceae) the pollen is widely scattered-explosively, and does not have a specific target. ...
... The dehiscence mechanism is the same in Stirlingia and in this genus all species are to a variable degree andromonoecious (Ladd and Wooller 1997). One species, S. latifolia, is wind pollinated with the anthers springing apart as the flower desiccates after the tepals have recurved (Ladd and Wooller 1997, see movie in supplementary materials) in a similar manner to that shown for Cornus canadensis L. (Edwards et al. 2005). However, other Stirlingia species are more likely to require insects to trigger the anthers and have proportionally fewer male flowers per inflorescence than S. latifolia (Ladd unpublished). ...
Full-text available
Pollen dispersal is the step in higher plant mating systems over which the parent plant has the least control as it is dependent on the vagaries of weather conditions (anemophily) or animal behaviour (animal pollinator activity). While many families have passive release from the anther the Proteaceae has a diversity of pollen dispersal methods. Flowers from a range of species in the Proteaceae, covering the majority of genera from each of the four main subfamilies, were examined to determine how pollen is dispersed and to gain an overall view of how male function varies within the family. This provides a basis for predicting the degree of the six likely fates of pollen released in this family. Only one group (subfamily Persoonioideae) and four genera in one other subfamily (Proteoideae) dispense pollen directly from the anthers onto a flower visitor. Five genera in the Proteoideae have explosive pollen release, while Symphionema may require vibration to release the pollen. All the remaining Proteoideae genera, the single species of Bellendenoideae, and all genera of the Grevilleoideae (except Sphalmium) have a pollen presenter where pollen is dispersed from the style of the flower. Ancestral Proteaceae were likely to have been insect pollinated and had relatively small flowers. Taxa with explosive pollen release may have evolved early in the family and may have been more abundant early in the fossil record. However, the taxa with pollen presenters became much more abundant throughout the Tertiary when many developed robust gynoecia that can accommodate larger vertebrate pollinators.
... As discussed, traditional measurements using Hirst-type methodology provide, at best, data with 1-hour temporal resolution that contain a great deal of uncertainty. High-speed cameras have been used in some experimental setups for observing pollen (and spore) release, which are very precise but have a limited operational time and are mainly suitable for laboratory conditions (Edwards et al., 2005;Timerman et al., 2014;Gallenmüller et al., 2018). As well as examining data with 1-minute resolution, this study also provided some first insights into sub-minute airborne pollen data. ...
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This is the first time that atmospheric concentrations of individual pollen types have been recorded by an automatic sampler with 1-hour and sub-hourly resolution (i.e. 1-minute and 1-second data). The data were collected by traditional Hirst type methods and state-of the art Rapid-E real-time bioaerosol detector. Airborne pollen data from 7 taxa, i.e. Acer negundo, Ambrosia, Broussonetia papyrifera, Cupressales (Taxaceae and Cupressaceae families), Platanus, Salix and Ulmus, were collected during the 2019 pollen season in Novi Sad, Serbia. Pollen data with daily, hourly and sub-hourly temporal resolution were analysed in terms of their temporal variability. The impact of turbulence kinetic energy (TKE) on pollen cloud homogeneity was investigated. Variations in Seasonal Pollen Integrals produced by Hirst and Rapid-E show that scaling factors are required to make data comparable. Daily average and hourly measurements recorded by the Rapid-E and Hirst were highly correlated and so examining Rapid-E measurements with sub-hourly resolution is assumed meaningful from the perspective of identification accuracy. Sub-hourly data provided an insight into the heterogenous nature of pollen in the air, with distinct peaks lasting ~5–10 min, and mostly single pollen grains recorded per second. Short term variations in 1-minute pollen concentrations could not be wholly explained by TKE. The new generation of automatic devices has the potential to increase our understanding of the distribution of bioaerosols in the air, provide insights into biological processes such as pollen release and dispersal mechanisms, and have the potential for us to conduct investigations into dose-response relationships and personal exposure to aeroallergens.
... Dynamic recoil is ubiquitous in biological systems to generate movement with greater mechanical power than possible with muscle alone (Alexander and Bennet-Clark, 1977;Burrows, 2003;Dickinson et al., 2000;Ilton et al., 2018), or plants and fungi that are without muscles at all (Coxall et al., 2005;Edwards et al., 2005;Noblin et al., 2012). Organisms and synthetic systems can utilize dynamic recoil to circumvent the force-velocity trade-off, performing tasks requiring large mechanical powers. ...
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Biological systems can generate motions with high acceleration and velocity via dynamic recoil. Traditionally, recoil dynamics in unstructured linear elastic systems are based on inertial and elastic properties, with the recoil velocity determined by the materials' speed of sound and the strain at recoil. Metamaterials with designed elastic structures and nonlinear interactions (e.g., magnetic interactions) have recently demonstrated the capability to control impulsive motions and manage high-rate energy transfer events. However, a predictive model for understanding the kinematics and recoil dynamics has not been developed. Here, we study the dynamic recoil that couples with a general nonlinear power-law interaction within a metamaterial framework. Starting with a 1D discrete model, we demonstrate how the nonlinear force interactions and the elastic structures in metamaterials control the dynamic performance. Under a weakly nonlinear condition, the governing equation of the dynamic recoil is described by the KdV (Korteweg-de Vries) equation and under the condition of strong nonlinearity by a more general strongly nonlinear wave equation. Our model predicts a “sonic vacuum” response in the recoiling metamaterials, where a near-zero speed of sound is induced by strongly nonlinear interactions and zero initial prestress. We propose a sequential wave motion during the dynamic recoil, where a linear wave propagates at a large stretch and switches to a nonlinear one below a critical stretch. We further discover that the nonlinear wave speed has a non-monotonic dependence upon the strength of the power-law interaction. We find good agreements in the recoil velocity by comparing our analytical model to experiments of the recoiling metamaterials with magnetic interactions. Our work demonstrates how power-law interactions within metamaterials can program dynamic recoil dynamics, setting the stage for new materials designs for energy management and conversion in high-rate applications.
... Inside, pollen is transported more than 22 cm (more than 100 times the flower), and in the presence of a steady wind in the open air, pollen can move further than a meter.Popping flowers increase the pollination of insects and allow wind pollination, contributing to the growing evidence that flowers often use multiple pollination mechanisms.The opening of a Bunchberry flower, recorded at 10,000 frames per second (the scale bar represents 1mm). (Source:Edwards et al., 2005) HYPTIS A hummingbird sips the nectar of this flower while in the air, without coming into contact with the flower. Therefore, pollination will never occur unless this plant throws pollen against the bird. ...
... In contrast, the elastic recoil of the distributed exoskeletal springs occurs more than 600 times faster (∼0.6 ms), resulting in the mandibles snapping shut (1,8,9). Fast elastic recoil of body elements is also used by some plants to disperse seeds and pollen, to feed, or to defend themselves (10)(11)(12). The Venus flytrap, for instance, captures insects by closing two jaw-like shell lobes in ∼100 ms (10). ...
Many small animals use springs and latches to overcome the mechanical power output limitations of their muscles. Click beetles use springs and latches to bend their bodies at the thoracic hinge and then unbend extremely quickly, resulting in a clicking motion. When unconstrained, this quick clicking motion results in a jump. While the jumping motion has been studied in depth, the physical mechanisms enabling fast unbending have not. Here, we first identify and quantify the phases of the clicking motion: latching, loading, and energy release. We detail the motion kinematics and investigate the governing dynamics (forces) of the energy release. We use high-speed synchrotron X-ray imaging to observe and analyze the motion of the hinge’s internal structures of four Elater abruptus specimens. We show evidence that soft cuticle in the hinge contributes to the spring mechanism through rapid recoil. Using spectral analysis and nonlinear system identification, we determine the equation of motion and model the beetle as a nonlinear single-degree-of-freedom oscillator. Quadratic damping and snap-through buckling are identified to be the dominant damping and elastic forces, respectively, driving the angular position during the energy release phase. The methods used in this study provide experimental and analytical guidelines for the analysis of extreme motion, starting from motion observation to identifying the forces causing the movement. The tools demonstrated here can be applied to other organisms to enhance our understanding of the energy storage and release strategies small animals use to achieve extreme accelerations repeatedly.
... Elastic recoil is often studied in animals where muscles load energy into springs, but diverse ectothermic organisms, from cnidarians to plants and fungi, use rapid release of energy that was stored slowly in tissues or fluid to fire nematocysts, seeds and spores, respectively, or to capture prey (Berg et al., 2019;de Ruiter et al., 2019;Edwards et al., 2005;Hayashi et al., 2010;Holstein and Tardent, 1984;Poppinga et al., 2016;Vincent et al., 2011). In cases where muscle cannot be described as a default motor for comparison, temperature effects on alternative physiological motors can be used to assess thermal robustness. ...
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Temperature influences many physiological processes that govern life as a result of the thermal sensitivity of chemical reactions. The repeated evolution of endothermy and widespread behavioral thermoregulation in animals highlight the importance of elevating tissue temperature to increase the rate of chemical processes. Yet, movement performance that is robust to changes in body temperature has been observed in numerous species. This thermally robust performance appears exceptional in light of the well-documented effects of temperature on muscle contractile properties, including shortening velocity, force, power and work. Here, we propose that the thermal robustness of movements in which mechanical processes replace or augment chemical processes is a general feature of any organismal system, spanning kingdoms. The use of recoiling elastic structures to power movement in place of direct muscle shortening is one of the most thoroughly studied mechanical processes; using these studies as a basis, we outline an analytical framework for detecting thermal robustness, relying on the comparison of temperature coefficients ( Q 10 values) between chemical and mechanical processes. We then highlight other biomechanical systems in which thermally robust performance that arises from mechanical processes may be identified using this framework. Studying diverse movements in the context of temperature will both reveal mechanisms underlying performance and allow the prediction of changes in performance in response to a changing thermal environment, thus deepening our understanding of the thermal ecology of many organisms.
Effective utilization of natural slight vibration with small movement speed is beneficial to development of energy harvest technology for solving energy problems. However, obtaining high current output when harvesting mechanical energy with ultralow vibration speed is difficult. Here, inspired by stomatopod (mantis) shrimp that has the ability to release pre-stored energy in a rapid action for generating an extremely fast strike, we propose an integrate-and-fire triboelectric (IF-TENG) to realize speed amplification. In this device, input mechanical energy from ultralow-speed vibrations can be firstly integrated, and then be instantaneously released in full when reaching a threshold. Thus, charged friction layers of the TENG can move at a high speed, leading to a relatively high output current. In addition to the speed amplification, the IF-TENG can stabilize the output current at different vibration speeds. Furthermore, we demonstrate that the idea of IF component could be introduced to both vertical contact-separation and lateral-sliding mode TENG for output performance enhancement, which supplies an efficient way for converting ultralow-speed vibration into electricity.
Background and Aims In angiosperms, many species disperse their seeds autonomously by the rapid movement of the pericarp. The fruits of these species often have long rod- or long plate-shaped pericarps, which are suitable for ejecting seeds during fruit dehiscence by bending or coiling. However, here we show that fruit with a completely different shape can also rely on the pericarp movement to disperse seeds explosively, as in Orixa japonica. Methods The fruit morphology was observed by hard tissue sectioning, scanning electron microscopy and micro-computed tomography, and the seed dispersal process was analysed using a high-speed camera. Comparisons were made of the geometric characteristics of pericarps before and after fruit dehiscence, and the mechanical process of pericarp movement was simulated with the aid of the finite element model. Key Results During fruit dehydration, the water drop-shaped endocarp of O. japonica with sandwich structure produced two-way bending deformation and cracking, and its width increased by more than three times before opening. Meanwhile the same shaped exocarp with uniform structure could only produce small passive deformation under relatively large external force. The endocarp pushed the exocarp to open by hygroscopic movement before seed launching, and the exocarp provided the acceleration for the seed launching through the reaction force. Conclusions Two layers of water drop-shaped pericarp in O. japonica form a structure similar to a slingshot, which launch the seed at a high speed during fruit dehiscence. Results suggest that plants with explosive seed dispersal appear to have a wide variety of fruit morphology, and through a combination of different external shapes and internal structures, they are able to move rapidly using many sophisticated mechanisms.
Full-text available
The pollination of flowering plants by animals represents a critical ecosystem service of great value to humanity, both monetary and otherwise. However, the need for active conservation of pollination interactions is only now being appreciated. Pollination systems are under increasing threat from anthropogenic sources, including fragmentation of habitat, changes in land use, modem agricultural practices, use of chemicals such as pesticides and herbicides, and invasions of non-native plants and animals. Honeybees, which themselves are non-native pollinators on most continents, and which may harm native bees and other pollinators, are nonetheless critically important for crop pollination. Recent declines in honeybee numbers in the United States and Europe bring home the importance of healthy pollination systems, and the need to further develop native bees and other animals as crop pollinators. The 'pollination crisis' that is evident in declines of honeybees and native bees, and in damage to webs of plant-pollinator interaction, may be ameliorated not only by cultivation of a diversity of crop pollinators, but also by changes in habitat use and agricultural practices, species reintroductions and removals, and other means. In addition, ecologists must redouble efforts to study basic aspects of plant-pollinator interactions if optimal management decisions are to be made for conservation of these interactions in natural and agricultural ecosystems.
Full-text available
There are two basic body designs for jumping that enable many animals to escape from predators, to increase their speed of locomotion or to launch into flight. Animals with long legs (bush babies, kangaroos and frogs, for example) have a levering power that enables them to use less force to jump the same distance as short-legged animals of comparable mass, whereas those with short legs must rely on the release of stored energy in a rapid catapult action. Insects exploit both designs: bush crickets use the leverage provided by long legs, fleas use stored energy to power their short legs, and grasshoppers combine features of each. Fleas are considered to be the champion jumpers, but here I show that froghoppers (spittle bugs) are in fact the real champions and that they achieve their supremacy by using a novel catapult mechanism for jumping.
Full-text available
The rapid closure of the Venus flytrap (Dionaea muscipula) leaf in about 100 ms is one of the fastest movements in the plant kingdom. This led Darwin to describe the plant as "one of the most wonderful in the world". The trap closure is initiated by the mechanical stimulation of trigger hairs. Previous studies have focused on the biochemical response of the trigger hairs to stimuli and quantified the propagation of action potentials in the leaves. Here we complement these studies by considering the post-stimulation mechanical aspects of Venus flytrap closure. Using high-speed video imaging, non-invasive microscopy techniques and a simple theoretical model, we show that the fast closure of the trap results from a snap-buckling instability, the onset of which is controlled actively by the plant. Our study identifies an ingenious solution to scaling up movements in non-muscular engines and provides a general framework for understanding nastic motion in plants.
In spruce-fir forests of central New Brunswick, species examined were Aralia nudicaulis, Chimaphila umbellata, Clintonia borealis, Cornus canadensis, Cypripedium acaule, Linnaea borealis, Maianthemum canadense, Medeola virginiana, Oxalis montana, Pyrola secunda, Trientalis borealis and Trillium undulatum. All taxa are insect-pollinated perennials and most exhibit clonal growth. Floral syndromes of the understory community are relatively unspecialized with many species possessing small white or green flowers. A total of 103 taxa of insects were collected from flowers during the 1979 season. Bombus spp. are the major pollinators of 5 of the 12 species. Syrphid flies, bee flies and halictid and andrenid bees were also commonly observed. Six species are completely dependent on insects for pollination, 4 species are weakly autogamous, one is strongly autogamous, and one appears to be apomictic. Four species are strongly self-compatible, one is dioecious, and the remainder display varying degrees of self-incompatibility. Despite this variation, outbreeding appears to be the most common reproductive mode. -from Authors
Self-replication is a process critical to natural and artificial life, but has been investigated to date mostly in simulation and in abstract systems. The near absence of physical demonstrations of self-replication is due primarily to the lack of a physical substrate in which self-replication can be implemented. This paper proposes a substrate composed of simple modular units, in which both simple and complex machines can construct and be constructed by other machines in the same substrate. A number of designs, both hand crafted and evolved, are proposed.
Stomatopods (mantis shrimp) are well known for the feeding appendages they use to smash shells and impale fish. Here we show that the peacock mantis shrimp (Odontodactylus scyllarus) generates an extremely fast strike that requires major energy storage and release, which we explain in terms of a saddle-shaped exoskeletal spring mechanism. High-speed images reveal the formation and collapse of vapour bubbles next to the prey due to swift movement of the appendage towards it, indicating that O. scyllarus may use destructive cavitation forces to damage its prey.
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