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Snake Strike Speeds
Topic Started: Jan 15 2015, 11:13 AM (1,852 Views)
M4A2E4
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Herbivore
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Hello everyone!

Quick question, is there any definitive research on snake strike speeds concerning a wide range of species? It seems like a lot of work has been put into recording strike speeds for venomous species, but I can't find anything about boas, pythons or colubrids. Nothing objective and scientific anyway.

I have read some anectdotal evidence from snake-keepers that the blood python and short-tail pythons are the "fastest striking non-venomous snake". Granted this really isn't the most reliable source of information ever, but I think it is a believable claim, given their extremely heavy, fat, slug stature.

These snakes look like fat sacks of crap because they literally are fat sacks of crap. These snakes apparently go about 3 months without defecating on average. IDK if anyone has looked into this specifically [there's strangely little peer-reviewed research into these species that I could find], but I'm betting that they do this as a "fecal ballast" for the same reasons that gaboon and rhinoceros vipers do it [which are themselves among the fastest striking snakes on Earth]. The extra poo and fat body makes a good anchor from which the snake can launch an extremely fast, powerful trike. That partly explains why most elapids have such slow strike speeds, since they tend to be much skinnier.



...that's the theory anyway. I think the STP = fastest striking non-venomous snake claim is credible, since it would make sense, but some actual, definitive research on the matter would be very nice. The the Blood python or the STP's can manage strike speeds comparable to gaboon or sawscale vipers they should maybe gain a little more popularity here on these forums. It does strike me as odd that the short-tail python complex are almost universally ignored here.
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Ceratodromeus
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from what i understand P. curtus is a rather poorly researched animal, though it's really neat :D

this paper is probably of some relevance, Thermal influences on foraging ability: body size, posture and cooling rate of an ambush predator, the
python Morelia spilota


http://onlinelibrary.wiley.com/doi/10.1046/j.1365-2435.1997.00093.x/pdf
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Taipan
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M4A2E4
Jan 15 2015, 11:13 AM
Quick question, is there any definitive research on snake strike speeds concerning a wide range of species? It seems like a lot of work has been put into recording strike speeds for venomous species, but I can't find anything about boas, pythons or colubrids. Nothing objective and scientific anyway.


Here is some useful information.

Debunking the viper's strike: harmless snakes kill a common assumption

David A. Penning, Baxter Sawvel, Brad R. Moon
Published 15 March 2016.DOI: 10.1098/rsbl.2016.0011

Abstract
To survive, organisms must avoid predation and acquire nutrients and energy. Sensory systems must correctly differentiate between potential predators and prey, and elicit behaviours that adjust distances accordingly. For snakes, strikes can serve both purposes. Vipers are thought to have the fastest strikes among snakes. However, strike performance has been measured in very few species, especially non-vipers. We measured defensive strike performance in harmless Texas ratsnakes and two species of vipers, western cottonmouths and western diamond-backed rattlesnakes, using high-speed video recordings. We show that ratsnake strike performance matches or exceeds that of vipers. In contrast with the literature over the past century, vipers do not represent the pinnacle of strike performance in snakes. Both harmless and venomous snakes can strike with very high accelerations that have two key consequences: the accelerations exceed values that can cause loss of consciousness in other animals, such as the accelerations experienced by jet pilots during extreme manoeuvres, and they make the strikes faster than the sensory and motor responses of mammalian prey and predators. Both harmless and venomous snakes can strike faster than the blink of an eye and often reach a target before it can move.

1. Introduction
For many organisms, defence and feeding involve different behaviours or different levels of performance during the same behaviour [1–4]. For many snakes, striking can be used both to catch prey and defend against predators [1,2]. Scientific descriptions of viper strikes date at least as far back as the early nineteenth century [5], and one of the first animal behaviours viewed with high-speed imagery was a rattlesnake strike [6,7]. For much of the twentieth century, the assumption that a viper strike represents ‘the fastest thing in nature’ has dominated our understanding of strike performance in snakes [5–8]. This assumption was tested with high-speed photography in 1954, which showed markedly slower strike velocities in rattlesnakes than generally expected [7]. However, the belief persists that vipers have the fastest strikes among snakes [9,10]. In order for a strike to be successful—regardless of the species involved—a snake must contact prey before it escapes or deter a threat before it causes harm. We used high-speed video recordings to test whether or not harmless ratsnakes can strike as fast as two species of vipers that often feed on similar prey and encounter similar kinds of predators.

We compared defensive strike distances, durations, and peak accelerations and velocities among species using data from 14 Texas ratsnakes (Pantherophis obsoletus; mean mass ± s.e. = 348 ± 71 g, snout–vent length = 91 ± 5.6 cm), 6 western cottonmouth vipers (Agkistrodon piscivorus; 273 ± 15.8 g, 68 ± 2.4 cm), 12 western diamond-backed rattlesnakes (Crotalus atrox; 634 ± 38 g, 95 ± 2.0 cm) and previously published studies [2,4,10,11]. We discuss the accelerations of snake strikes in relation to the known physiological effects experienced during high accelerations, and we compare strike durations with mammalian startle-response times.

2. Material and methods
We presented each snake with a target (stuffed glove) and recorded 4–8 defensive strikes per snake. We performed all trials at 27°C. To record strikes, we used a Redlake (San Diego, CA, USA) MotionScope high-speed camera set at 250 Hz and a shutter speed of less than or equal to 0.004 s. Depending on their size, we recorded snakes in an arena measuring 30 × 30 × 60 cm or 65 × 95 × 57 cm with a scale grid visible in the same plane as each snake's strike.

We analysed only strikes that were perpendicular to the camera. From the high-speed videos, we derived strike distance as the linear distance between the snake's snout and the target at the onset of the strike, and strike duration as the total time from the initiation of strike movement to first contact with the target. Maximum velocities and accelerations are the highest single (frame-to-frame) values obtained from analyses of filtered coordinates ([2]; 50 Hz cut-off Butterworth filter). We analysed peak values for each variable (often from different strikes [2]) from each snake and obtained the variables by digitizing videos using Tracker 4.87 software (Open Source Physics, http://www.opensourcephysics.org/index.cfm).

We log-transformed the data and treated strike duration (s), distance (m), maximum acceleration (ms–2) and maximum velocity (ms–1) as dependent variables. We used an ANCOVA for each dependent variable with species as the independent variable and body mass as the covariate. We also compared maximum accelerations and velocities with more complex models (one for acceleration and one for velocity) incorporating mass, species, strike distance (from the same strike that produced the maximum values) and their interactions, and subsequently excluded non-significant interactions. All model assumptions were tested and met. For maximum strike distance, two outliers were removed (standardized residual > 2) to meet assumptions. We used JMP Pro 11.0.0 and RStudio (0.99.441) for analyses, and determined significance whenever p < 0.05. We lack sufficient data for analysing muscle cross-sectional areas in these species.

3. Results and discussion
All snakes struck with very high accelerations (range = 98–279 ms–2) and velocities (2.10–3.53 ms–1), over short distances (8.6–27.0 cm), and with short durations (48–84 ms). Strike performance was not significantly different among species for three of the four variables (figure 1; table 1). Snakes displayed similar strike accelerations (F2,28 = 1.5, p > 0.23), velocities (F2,28 = 1.8, p > 0.17) and durations (F2,28 = 2.6, p > 0.09). However, peak strike distance differed significantly (F2,26 = 7.2, p < 0.01), with rattlesnakes striking shorter maximum distances than ratsnakes. The lack of corresponding differences in duration or velocity was owing to peak values coming from different and variable strikes. There was no difference among species in maximum accelerations (F2,27 = 0.91, p > 0.38) or velocities (F2,27 = 1.9, p > 0.16) in models when both mass and strike distance were included as covariates. Ratsnake strikes matched or exceeded the performance of viper strikes in other studies (table 1).

Posted Image
Figure 1.
Video images of defensive strikes by Pantherophis obsoletus (top) and Crotalus atrox (bottom) recorded at 250 frames s–1 with a Keyence camera (Itasca, IL, USA).

Posted Image

Strike accelerations were similar and impressively high in all three species that we studied (table 1) and are similar to those of feeding strikes [1]. Strike accelerations are probably more important than the peak velocities [2] because strikes do not involve a chase. These accelerations have two sets of important consequences. First, the high accelerations keep the strike durations shorter than the response times of mammalian predators and prey. Mammalian startle responses can activate muscles in 14–151 ms, and produce observable movement in as little as 60–395 ms [12,13]; non-mammalian response times are not well known. Our results demonstrate that both harmless and venomous snake strikes can reach their targets in ca 50–90 ms, which is often faster than mammals can respond. These strikes are literally faster than the blink of an eye, which takes 202 ms in humans [14]. However, strike performance and prey capture in nature may not always be this high [15]. If strike durations are longer than the response times of the targets, then strike accelerations and reaches must be high enough to overcome the predator or prey once it has initiated a response. Our two highest strike accelerations (274 ms–2 from a ratsnake and 279 ms–2 from a rattlesnake) were approximately an order of magnitude greater than the jumping accelerations of black-tailed jackrabbits [16], and 30% faster than those of kangaroo rats [17,18], whose escape behaviour may have evolved in response to snake predators [18]. The impressive strike performance across species indicates that selection for rapid strike performance acts on many snakes. Snakes that defend against similar kinds of predators or feed on similar kinds of prey, such as small mammals, probably all need to have comparably high accelerations and short strike durations.

A second important consequence of strike performance involves physiological tolerances to high accelerations. Blood flow to the brain may be reduced during rapid head-first accelerations [19], such as those in snake strikes. Humans rarely experience accelerations as high as those of snake strikes. Fighter-jet pilots launching from an aircraft carrier experience take-off accelerations of only 27–49 ms–2 [20]. Without the aid of anti-gravity suits, pilots can lose consciousness at accelerations that are 21–23% of the values achieved by our snakes [19]. Even with anti-G suits, pilots lose the ability to stand up from sitting at accelerations of ca 30 ms–2 and lose the ability to move their limbs when accelerations reach 78 ms–2 [19]. Acceleration duration and heart-to-head distance are important in physiological responses to acceleration [19], as is size [21], which complicates our ability to understand how acceleration affects other animals. The long distances between the heart and head in many snakes could make them susceptible to impaired cranial blood flow during strikes, similar to the impairment that can occur during climbing [22], but the very short strike durations may preclude such physiological disruptions. The events at the end of a strike may have additional effects [19], but the effects of rapid deceleration and impact on a soft-bodied target are well tolerated by snakes.

Despite statements in the literature [9,10], vipers do not strike faster than all other snakes. Ratsnakes and vipers alike have similarly impressive strikes. Such high accelerations disrupt the physiology of other animals, but are well tolerated by the snakes and allow them to make contact before their targets can respond. Selection for high strike performance may be heavily influenced by the target's sensory and motor response capacities, which are an understudied aspect of predator–prey interactions. With so few snakes having been studied thus far, it seems likely that future research will reveal a greater range of performance in these diverse and successful predators.

http://rsbl.royalsocietypublishing.org/content/12/3/20160011





References

1. ↵LaDuc TJ. 2002 Does a quick offense equal a quick defense? Kinematic comparisons of predatory and defensive strikes in the western diamond-backed rattlesnake (Crotalus atrox). In Biology of the vipers (eds GW Schuettt, M Hoggren, ME Douglas, HW Greene), pp. 267–278. Eagle Mountain, UT: Eagle Mountain Publishing.
2. ↵Herrel A, Huyghe K, Oković P, Lisičić D, Tadić Z. 2011 Fast and furious: effects of body size on strike performance in an arboreal viper Trimeresurus (Cryptelytrops) albolabris. J. Exp. Zool. A. 315, 22–29. (doi:10.1002/jez.645)
3. Herrel A, Gibb AC. 2006 Ontogeny of performance in vertebrates. Physiol. Biochem. Zool. 79, 1–6. (doi:10.1086/498196)CrossRefMedlineWeb of Science
4. ↵Shine R, Li-Xin S, Fitzgerald M, Kearney M. 2002 Antipredator responses of free-ranging pit vipers (Gloydius shedaoensis, Viperidae). Copeia 2002, 843–850. (doi:10.1643/0045-8511(2002)002[0843:AROFRP]2.0.CO;2)CrossRef
5. ↵Klauber LM. 1956 Rattlesnakes: their habits, life histories, and influence on mandkind. Berkeley, CA: University of California Press.
6. ↵Janoo A, Gasc J-P. 1992 High speed motion analysis of the predatory strike and fluorographic study of oesophageal deglutition in Vipera ammodytes: more than meets the eye. Amphibia–Reptilia 13, 315–325. (doi:10.1163/156853892X00021)
7. ↵Van Riper W. 1954 Measuring the speed of a rattlesnake's strike. Anim. Kingdom 57, 50–53.
8. ↵Whitaker PB, Ellis K, Shine R. 2000 The defensive strike of the Eastern Brownsnake, Pseudonaja textilis (Elapidae). Funct. Ecol. 14, 25–31. (doi:10.1046/j.1365-2435.2000.00385.x)CrossRef
9. ↵Vincent SE, Herrel A, Irschick DJ. 2005 Comparisons of aquatic versus terrestrial predatory strikes in the pitviper, Agkistrodon piscivorus. J. Exp. Zool. A. 303A, 476–488. (doi:10.1002/jez.a.179)
10. ↵Young BA. 2010 How a heavy-bodied snake strikes quickly: high-power axial musculature in the puff adder (Bitis arietans). J. Exp. Zool. A. 313, 114–11. (doi:10.1002/jez.579)
11.↵Araújo MS, Martins M. 2007 The defensive strike of five species of lanceheads of the genus Bothrops (Viperidae). Braz. J. Biol. 67, 327–332. (doi:10.1590/S1519-69842007000200019)CrossRefMedline
12. ↵Davis M. 1984 The mammalian startle response. In Neural mechanisms of startle behaviour (ed. RC Eaton), pp. 287–351. New York, NY: Plenum Press.
13. ↵Yilmaz M, Meister M. 2013 Rapid innate defensive responses of mice to looming visual stimuli. Curr. Biol. 23, 2011–2015. (doi:10.1016/j.cub.2013.08.015)CrossRefMedline
14. ↵Caffier PP, Erdmann U, Ullsperger P. 2003 Experimental evaluation of eye-blink parameters as a drowsiness measure. Eur. J. Appl. Physiol. 89, 319–325. (doi:10.1007/s00421-003-0807-5)CrossRefMedlineWeb of Science
15. ↵Clark RW, Tangco S, Barbour MA. 2012 Field video recordings reveal factors influencing predatory strike success of free-ranging rattlesnakes (Crotalus spp.). Anim. Behav. 84, 183–190. (doi:10.1016/j.anbehav.2012.04.029)CrossRefWeb of Science
16. ↵Carrier DR. 1996 Ontogenetic limits on locomotor performance. Physiol. Zool. 69, 467–488. (doi:10.1086/physzool.69.3.30164211)
17. ↵Müller UK, Kranenbarg S. 2004 Power at the tip of the tongue. Science 304, 217–219. (doi:10.1126/science.1097894)Abstract/FREE Full Text
18. ↵Biewener AA, Blickhan R. 1988 Kangaroo rat locomotion: design for elastic energy storage or acceleration? J. Exp. Biol. 140, 243–255.Abstract/FREE Full Text
19. ↵Balldin U. 2002 Acceleration effects on fighter pilots. In Medical aspects of harsh environments (eds K Pandoff, R Burr), pp. 1014–1027. Washington, DC: Department of the Army.
20. ↵Patterson D, Monti A, Brice C, Dougal R, Pettus R, Srinivas D, Dilipchandra K, Bertoncelli T. 2002 Design and simulation of an electromagnetic aircraft launch system. In Proc. 37th Industry Applications Ann. Meeting, 13–18 October 2002; Pittsburgh, PA, USA, pp. 1950–1957. Piscataway, NJ: Institute of Electrical and Electronic Engineers, Inc.
21. ↵White CR, Seymour RS. 2013 The role of gravity in the evolution of mammalian blood pressure. Evolution 68, 901–908. (doi:10.1111/evo.12298)
22. Lillywhite HB. 1987 Circulatory adaptations of snakes to gravity. Am. Zool. 27, 81–95. (doi:10.1093/icb/27.1.81)Abstract/FREE Full Text

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Wouldn't be surprised if it was bloods. They hit hard and fast.
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M4A2E4
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Fascinating study!

I gotta say though, it does strike me as incredibly weird that a thin bodied species like a ratsnake could strike with similar acceleration and speed as a heavy bodied pitviper, which is built almost entirely around strike speed and acceleration.

Also, even though it was part of a different study, the puff adder strike acceleration being so much slower than rattlesnakes or ratsnakes is absolutely bizarre.
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Ceratodromeus
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eh, i'm not entirely surprised the smaller bodied snakes accelerated as quickly as the puff adder; ratsnakes are insane in that way.

the fish eating snakes have always come across as some of the faster striking animals because of their dietary preferences.
Here is an interesting study on that matter;

Sweeping and striking: a kinematic study of the trunk during prey capture in three thamnophiine snakes
Summary
The trunk plays an obvious and important role in the prey capture behavior of many species of snake, yet trunk function during predatory strikes is poorly understood. Axial kinematics of three thamnophiine snakes (Thamnophis couchii, Thamnophis elegans and Nerodia rhombifer) were studied to quantify differences between sideways-directed and forward-directed attacks and to investigate strike diversity at relatively low phylogenetic levels. Feeding strikes were filmed at 60 Hz, and 13 points along the head and body were digitized. These points were used to calculate body segment displacement, rotation and velocity during predatory strikes. Kinematic analysis revealed significant differences in the foraging modes of these aquatic-feeding species. T. couchii displayed a stereotypical pre-strike posture in which the entire body was arranged in a series of loops directed towards the prey. Forward displacement of body segments sometimes occurred over the entire body in T. couchii but was restricted to the anterior one-third of the trunk in T. elegans and N. rhombifer. T. couchii and N. rhombifer both struck rapidly compared with T. elegans, although N. rhombifer typically had a short strike distance. N. rhombifer struck significantly faster than T. elegans. Aquatic prey capture diversity appears to reflect ecological diversity in thamnophiine snakes.

Results

The western aquatic garter snake Thamnophis couchii
"This species captured prey via fast, forward-directed strikes (mean maximum velocity, 86 cm s-1; mean maximum acceleration, 19 m s-2) that could be initiated either terrestrially, in midwater or from rest underwater. Snakes visually oriented to specific prey items and almost always exhibited a preparatory phase in which the body was pointed towards the prey with the trunk arranged in a series of half-loops (Fig. 3). Once this posture was attained, snakes typically struck from rest or while slowly moving towards the prey using the posterior trunk while maintaining the anterior loops. This species launched directed strikes at prey from relatively long distances: mean maximum prey distance was 6.8 cm (3.9 head lengths), and successful strikes just over 8.8 cm (5 head lengths) were observed. Strikes launched without a brace point, usually from mid- or underwater, exhibited straightening and forward displacement of the anterior two-thirds of the trunk and straightening and backwards displacement of the posterior one-third. When the snake was able to brace a portion of its body against an object in the tank, backwards displacement of the posterior trunk was not observed.
Posted Image
"Head acceleration was high (18.1 m s-2), and individuals typically reached peak velocity (86 cm s-1) within 60 ms of strike initiation (Fig. 4). Segment angle was low in the anterior-most segments and decreased across all segments coincident with increasing velocity. Mean path angle dropped sharply in the anterior trunk as velocity increased. In the posterior half of the trunk, path angle decreased after peak velocity was attained. In addition, path angle in these posterior points continued to decrease as path angle slightly increased in the anterior points late in the strike cycle. Segment displacements in the direction of the strike were high for the first four segments. During head acceleration, the last three segments exhibited displacement away from the prey, suggesting that the posterior trunk plays a role in balancing strike forces."
Posted Image
Head velocity (A), segment angle (B), path angle (C) and forward displacement (D) profiles for Thamnophis couchii. Graphs have been standardized to the time of peak velocity so that maximum velocity is reached at t=0. Error bars represent 1 s.e.m. Anterior body points are yellow, posterior points are blue. T. couchii strikes showed the highest velocities of the three species measured. Segment straightening was apparent for most positions along the trunk. Segment angles generally did not exceed 90°, indicating that the anterior ends of all segments along the trunk were pointed in the direction of the strike. Head acceleration was accompanied by substantial angular rotation in segments 1-4. Path angles for most anterior segments were under 90° and decreased with increasing velocity, indicating that these segments traveled close to the calculated strike vector. Path angles exceeded 90° for posterior segments shortly before maximum velocity was achieved. This may have been the result of backwards displacement of posterior body segments in reaction to head-accelerating forces generated by the anterior trunk. Rearwards displacement of the posterior segments was sometimes observed in video sequences. Forward displacement was substantial and decreased in an anterior to posterior direction.

The western terrestrial garter snake Thamnophis elegans
"T. elegans also captured prey by striking forward from rest or while swimming forward. Trunk recruitment was variable in this species: anterior loops were usually straightened during the initial phase of the strike (Fig. 7). In addition, large, posterior loops were sometimes straightened, especially when the strike covered a distance of four or more head lengths. In these instances, the forward strike transitioned into forward swimming and/or sideways sweeping. Prey appeared to be detected visually. Trunk looping was not as pronounced as that seen in T. couchii, and strikes were often initiated with only the anterior one-third of the trunk pointing towards the prey."
Posted Image
"T. elegans strikes reached mean peak velocities of approximately 46 cm s-1 (35 head lengths s-1; Fig. 8), approximately half that of T. couchii. Accelerations were also relatively lower, reaching mean peak values of approximately 9 m s-2 (540 head lengths s-2). Head acceleration was sustained for 80-100 ms before peak velocity was reached. Head segment angle decreased as velocity increased, although not to the same extent as in T. couchii. Segment angle also decreased in the first segment with increasing velocity, but showed little change in more-posterior segments. Path angles of the head and segments 1 and 2 decreased with increasing velocity. Forward displacement was largely restricted to the three anterior-most segments. More-posterior segments experienced a small amount of backwards displacement during the course of the strike."
Posted Image
Head velocity (A), segment angle (B), path angle (C) and forward displacement (D) profiles for Thamnophis elegans. Graphs have been standardized to time of peak velocity so that maximum velocity is reached at t=0. Error bars represent 1 s.e.m. Anterior body points are yellow, posterior points are blue. Head velocity during strikes was higher than in sweeps but still lower than in the other species examined. Segment straightening was apparent for positions 2 and 3 as the head approached peak velocity. Head segment angle was variable during the initial stages of head acceleration, decreasing shortly before the head reached peak velocity. Segment 1 segment angle decreased rapidly after peak velocity. More-posterior segment angles decreased slightly after peak velocity. Path angles for the three anterior-most positions dropped sharply as the head accelerated, while positions 4-8 showed little change from an initial path of 90°. Forward displacement was greatest at the snout and positions 1 and 2.

The diamond-backed water snake Nerodia rhombifer
"This species sometimes used a low-speed, high-amplitude, open-mouth sweeping behavior that resembled that found in T. elegans. More commonly, however, N. rhombifer displayed a high-speed strike from an ambush position (Fig. 9). During this behavior, the snake remained motionless, often with its head out of the water. Strikes were elicited by prey swimming close to the head or sometimes by prey contacting the anterior trunk. Often, these strikes showed a strong lateral component as the head was swung rapidly to the side to capture prey. N. rhombifer showed a remarkable ability to bend the neck and anterior trunk around to capture prey detected behind the head. In some of these instances, prey were trapped between the head and anterior trunk and corralled into the open jaws."
Posted Image
"Strikes were relatively rapid, reaching a mean peak velocity of 84 cm s-1 (42 head lengths s-1; Fig. 10). Accelerations were also high relative to T. elegans, reaching mean peak values of 20 m s-2 (1027 head lengths s-2). At the beginning of the strike, the head was oriented 90° relative to the prey item. Head angle and segment angle 1 decreased as the head was accelerated to roughly 20°. More-posterior segments decreased their segment angle to a much lesser degree than the head and segment 1. Path angles also dropped sharply for the head and segment 1 as velocity increased. More-posterior segments generally maintained path angles greater than 90°, indicating that these portions of the trunk were traveling away from the strike."
Posted Image
Head velocity (A), segment angle (B), path angle (C) and forward displacement (D) profiles for Nerodia rhombifer. Graphs have been standardized to time of peak velocity so that maximum velocity is reached at t=0. Error bars represent 1 s.e.m. Anterior body points are yellow, posterior points are blue. The snake achieves peak velocity in approximately 50-60 ms. Starting head segment angle is approximately 90°, indicating that the head is not closely aligned to the direction of the strike at the onset of this behavior. The head and segment 1 show a sharp decrease in segment angle as the head is accelerated. Segment angle in these segments continues to decrease after peak velocity. More-posterior segments undergo relatively little angular change. Head and segment 1 path angle also markedly decrease with head velocity, while more-posterior segment angles are largely unchanged. Forward displacement is greatest at the snout, followed by body position 1. More-posterior positions experience minor displacement, with positions 5-10 undergoing periods of rearwards movement.
http://jeb.biologists.org/content/206/14/2381.long
Edited by Ceratodromeus, Mar 19 2016, 02:53 AM.
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M4A2E4
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So I'm about to make a huge embarrassment out of myself with my pure amateurism.

I tried recording the strike speed of a sub-adult sumatran short-tail python using a 1-inch grid and an iPhone camera.

The results are bad and imprecise beyond measure. Video was shot at a bad angle that gives a distorted view of strike distance, and I'm using extremely rudimentary means to calculate strike time, but here's what I got:



Strike distance was ~6-7inches, estimating, ~or 0.15-0.18m. The combination of the strike leading slightly towards the camera and slightly upwards makes this hard to calculate [each square is 1inch]

Strike time was ~0.45 seconds in the video. The video itself was shot at 240fps, and *native* video playback should be at 30fps.

Unless I buttboned my math, that makes the real-time strike 0.0562 seconds.

A strike traveling 0.015-0.018m over the course of 0.0562 seconds produces a strike speed ranging from 2.6meters per second to 3.2 meters per second.

That is... actually incredibly fast, exceeding the strike speeds of puff adders, copper heads, rattlesnakes, and the kingsnake.

It makes me more suspricious that I screwed my measurements.

Lets say I'm a big fat biased snake fanboy and I massively exaggerated my measurements, and that it may have been more like 5 inches at 0.5 seconds playback time, or 0.0625 second real time.

5 inches = 0.127m.
0.127m/0.0625seconds = 2.032m/s

That is far more modest. Actually that's extremely low for a snake that is built like this and supposedly bases its entire body physiology around high strike speeds.





Results: a sub-adult sumatran short tail python cane achieve a strike speed ranging anywhere from 2m/s to 3.2m/s. This is either pretty "meh" or blindingly fast to the point that it is nearly impossible for any animal to evade a strike from a short distance.

Conclusion: I'm total ass at pretending to make scientific studies.
Also I'm under the assumption that native video playback would be 30fps, or that the "slow mo" at 240fps would slow down 8x when played at normal speed. It is possible that video playback on an iphone is actually 60fps, in which case all of these results get cut in half.
Edited by M4A2E4, Apr 14 2016, 12:05 PM.
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Ceratodromeus
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Mar 17 2016, 07:54 PM
M4A2E4
Jan 15 2015, 11:13 AM
Quick question, is there any definitive research on snake strike speeds concerning a wide range of species? It seems like a lot of work has been put into recording strike speeds for venomous species, but I can't find anything about boas, pythons or colubrids. Nothing objective and scientific anyway.


Here is some useful information.

Debunking the viper's strike: harmless snakes kill a common assumption

David A. Penning, Baxter Sawvel, Brad R. Moon
Published 15 March 2016.DOI: 10.1098/rsbl.2016.0011

Abstract
To survive, organisms must avoid predation and acquire nutrients and energy. Sensory systems must correctly differentiate between potential predators and prey, and elicit behaviours that adjust distances accordingly. For snakes, strikes can serve both purposes. Vipers are thought to have the fastest strikes among snakes. However, strike performance has been measured in very few species, especially non-vipers. We measured defensive strike performance in harmless Texas ratsnakes and two species of vipers, western cottonmouths and western diamond-backed rattlesnakes, using high-speed video recordings. We show that ratsnake strike performance matches or exceeds that of vipers. In contrast with the literature over the past century, vipers do not represent the pinnacle of strike performance in snakes. Both harmless and venomous snakes can strike with very high accelerations that have two key consequences: the accelerations exceed values that can cause loss of consciousness in other animals, such as the accelerations experienced by jet pilots during extreme manoeuvres, and they make the strikes faster than the sensory and motor responses of mammalian prey and predators. Both harmless and venomous snakes can strike faster than the blink of an eye and often reach a target before it can move.

1. Introduction
For many organisms, defence and feeding involve different behaviours or different levels of performance during the same behaviour [1–4]. For many snakes, striking can be used both to catch prey and defend against predators [1,2]. Scientific descriptions of viper strikes date at least as far back as the early nineteenth century [5], and one of the first animal behaviours viewed with high-speed imagery was a rattlesnake strike [6,7]. For much of the twentieth century, the assumption that a viper strike represents ‘the fastest thing in nature’ has dominated our understanding of strike performance in snakes [5–8]. This assumption was tested with high-speed photography in 1954, which showed markedly slower strike velocities in rattlesnakes than generally expected [7]. However, the belief persists that vipers have the fastest strikes among snakes [9,10]. In order for a strike to be successful—regardless of the species involved—a snake must contact prey before it escapes or deter a threat before it causes harm. We used high-speed video recordings to test whether or not harmless ratsnakes can strike as fast as two species of vipers that often feed on similar prey and encounter similar kinds of predators.

We compared defensive strike distances, durations, and peak accelerations and velocities among species using data from 14 Texas ratsnakes (Pantherophis obsoletus; mean mass ± s.e. = 348 ± 71 g, snout–vent length = 91 ± 5.6 cm), 6 western cottonmouth vipers (Agkistrodon piscivorus; 273 ± 15.8 g, 68 ± 2.4 cm), 12 western diamond-backed rattlesnakes (Crotalus atrox; 634 ± 38 g, 95 ± 2.0 cm) and previously published studies [2,4,10,11]. We discuss the accelerations of snake strikes in relation to the known physiological effects experienced during high accelerations, and we compare strike durations with mammalian startle-response times.

2. Material and methods
We presented each snake with a target (stuffed glove) and recorded 4–8 defensive strikes per snake. We performed all trials at 27°C. To record strikes, we used a Redlake (San Diego, CA, USA) MotionScope high-speed camera set at 250 Hz and a shutter speed of less than or equal to 0.004 s. Depending on their size, we recorded snakes in an arena measuring 30 × 30 × 60 cm or 65 × 95 × 57 cm with a scale grid visible in the same plane as each snake's strike.

We analysed only strikes that were perpendicular to the camera. From the high-speed videos, we derived strike distance as the linear distance between the snake's snout and the target at the onset of the strike, and strike duration as the total time from the initiation of strike movement to first contact with the target. Maximum velocities and accelerations are the highest single (frame-to-frame) values obtained from analyses of filtered coordinates ([2]; 50 Hz cut-off Butterworth filter). We analysed peak values for each variable (often from different strikes [2]) from each snake and obtained the variables by digitizing videos using Tracker 4.87 software (Open Source Physics, http://www.opensourcephysics.org/index.cfm).

We log-transformed the data and treated strike duration (s), distance (m), maximum acceleration (ms–2) and maximum velocity (ms–1) as dependent variables. We used an ANCOVA for each dependent variable with species as the independent variable and body mass as the covariate. We also compared maximum accelerations and velocities with more complex models (one for acceleration and one for velocity) incorporating mass, species, strike distance (from the same strike that produced the maximum values) and their interactions, and subsequently excluded non-significant interactions. All model assumptions were tested and met. For maximum strike distance, two outliers were removed (standardized residual > 2) to meet assumptions. We used JMP Pro 11.0.0 and RStudio (0.99.441) for analyses, and determined significance whenever p < 0.05. We lack sufficient data for analysing muscle cross-sectional areas in these species.

3. Results and discussion
All snakes struck with very high accelerations (range = 98–279 ms–2) and velocities (2.10–3.53 ms–1), over short distances (8.6–27.0 cm), and with short durations (48–84 ms). Strike performance was not significantly different among species for three of the four variables (figure 1; table 1). Snakes displayed similar strike accelerations (F2,28 = 1.5, p > 0.23), velocities (F2,28 = 1.8, p > 0.17) and durations (F2,28 = 2.6, p > 0.09). However, peak strike distance differed significantly (F2,26 = 7.2, p < 0.01), with rattlesnakes striking shorter maximum distances than ratsnakes. The lack of corresponding differences in duration or velocity was owing to peak values coming from different and variable strikes. There was no difference among species in maximum accelerations (F2,27 = 0.91, p > 0.38) or velocities (F2,27 = 1.9, p > 0.16) in models when both mass and strike distance were included as covariates. Ratsnake strikes matched or exceeded the performance of viper strikes in other studies (table 1).

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Figure 1.
Video images of defensive strikes by Pantherophis obsoletus (top) and Crotalus atrox (bottom) recorded at 250 frames s–1 with a Keyence camera (Itasca, IL, USA).

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Strike accelerations were similar and impressively high in all three species that we studied (table 1) and are similar to those of feeding strikes [1]. Strike accelerations are probably more important than the peak velocities [2] because strikes do not involve a chase. These accelerations have two sets of important consequences. First, the high accelerations keep the strike durations shorter than the response times of mammalian predators and prey. Mammalian startle responses can activate muscles in 14–151 ms, and produce observable movement in as little as 60–395 ms [12,13]; non-mammalian response times are not well known. Our results demonstrate that both harmless and venomous snake strikes can reach their targets in ca 50–90 ms, which is often faster than mammals can respond. These strikes are literally faster than the blink of an eye, which takes 202 ms in humans [14]. However, strike performance and prey capture in nature may not always be this high [15]. If strike durations are longer than the response times of the targets, then strike accelerations and reaches must be high enough to overcome the predator or prey once it has initiated a response. Our two highest strike accelerations (274 ms–2 from a ratsnake and 279 ms–2 from a rattlesnake) were approximately an order of magnitude greater than the jumping accelerations of black-tailed jackrabbits [16], and 30% faster than those of kangaroo rats [17,18], whose escape behaviour may have evolved in response to snake predators [18]. The impressive strike performance across species indicates that selection for rapid strike performance acts on many snakes. Snakes that defend against similar kinds of predators or feed on similar kinds of prey, such as small mammals, probably all need to have comparably high accelerations and short strike durations.

A second important consequence of strike performance involves physiological tolerances to high accelerations. Blood flow to the brain may be reduced during rapid head-first accelerations [19], such as those in snake strikes. Humans rarely experience accelerations as high as those of snake strikes. Fighter-jet pilots launching from an aircraft carrier experience take-off accelerations of only 27–49 ms–2 [20]. Without the aid of anti-gravity suits, pilots can lose consciousness at accelerations that are 21–23% of the values achieved by our snakes [19]. Even with anti-G suits, pilots lose the ability to stand up from sitting at accelerations of ca 30 ms–2 and lose the ability to move their limbs when accelerations reach 78 ms–2 [19]. Acceleration duration and heart-to-head distance are important in physiological responses to acceleration [19], as is size [21], which complicates our ability to understand how acceleration affects other animals. The long distances between the heart and head in many snakes could make them susceptible to impaired cranial blood flow during strikes, similar to the impairment that can occur during climbing [22], but the very short strike durations may preclude such physiological disruptions. The events at the end of a strike may have additional effects [19], but the effects of rapid deceleration and impact on a soft-bodied target are well tolerated by snakes.

Despite statements in the literature [9,10], vipers do not strike faster than all other snakes. Ratsnakes and vipers alike have similarly impressive strikes. Such high accelerations disrupt the physiology of other animals, but are well tolerated by the snakes and allow them to make contact before their targets can respond. Selection for high strike performance may be heavily influenced by the target's sensory and motor response capacities, which are an understudied aspect of predator–prey interactions. With so few snakes having been studied thus far, it seems likely that future research will reveal a greater range of performance in these diverse and successful predators.

http://rsbl.royalsocietypublishing.org/content/12/3/20160011





References

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2. ↵Herrel A, Huyghe K, Oković P, Lisičić D, Tadić Z. 2011 Fast and furious: effects of body size on strike performance in an arboreal viper Trimeresurus (Cryptelytrops) albolabris. J. Exp. Zool. A. 315, 22–29. (doi:10.1002/jez.645)
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12. ↵Davis M. 1984 The mammalian startle response. In Neural mechanisms of startle behaviour (ed. RC Eaton), pp. 287–351. New York, NY: Plenum Press.
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Here's a video via national geographic!
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Viper's strike quantified in nature for the first time
Research aims to understand factors that determine the success/failure of a strike or escape in predator-prey interactions


Date: January 13, 2017
Source: University of California - Riverside
Summary:
The antagonistic predator-prey relationship is of interest to evolutionary biologists because it often leads to extreme adaptations in both the predator and prey. One such relationship is seen in the rattlesnake-kangaroo rat system. Now researchers have captured in high speed (500 frames per second) a rattlesnake trying to capture a kangaroo rat.

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What factors determine the success/failure of a strike or escape in predator-prey relationships?
Credit: Higham lab, UC Riverside

Feeding is paramount to the survival of almost every animal, and just about every living organism is eaten by another. Not surprisingly, the animal kingdom shows many examples of extreme specialization -- the chameleon's tongue, fox diving into snow, cheetah sprinting -- for capturing prey or escaping predators.

The antagonistic predator-prey relationship is of interest to evolutionary biologists because it often leads to extreme adaptations in both the predator and prey. One such relationship is seen in the rattlesnake-kangaroo rat system -- a model system for studying the dynamics of high-power predator-prey interactions that can be observed under completely natural conditions.

Curiously, however, very little is known about the strike performance of rattlesnakes under natural conditions. But that is now about to change because technological advances in portable high-speed cameras have made it possible for biologists like Timothy Higham at the University of California, Riverside to capture three-dimensional video in the field of a rattlesnake preying on a kangaroo rat.

"Predator-prey interactions are naturally variable -- much more so than we would ever observe in a controlled laboratory setting," said Higham, an associate professor of biology, who led the research project. "Technology is now allowing us to understand what defines successful capture and evasion under natural conditions. It is under these conditions in which the predator and prey evolve. It's therefore absolutely critical to observe animals in their natural habitat before making too many conclusions from laboratory studies alone."

A question Higham and his team are exploring in predator-prey relationships is: What factors determine the success/failure of a strike or escape? In the case of the rattlesnake and kangaroo rat, the outcome, they note, appears to depend on both the snake's accuracy and the ability of the kangaroo rat to detect and evade the viper before being struck.

"We obtained some incredible footage of Mohave rattlesnakes striking in the middle of the night, under infrared lighting, in New Mexico during the summer of 2015," Higham said. "The results are quite interesting in that strikes are very rapid and highly variable. The snakes also appear to miss quite dramatically -- either because the snake simply misses or the kangaroo rat moves out of the way in time."

Many studies have examined snake strikes, but the new work is the first study to quantify strikes using high-speed video (500 frames per second) in the wild.

Study results appear in Scientific Reports.

In the paper, Higham and his coauthors conclude that rattlesnakes in nature can greatly exceed the defensive strike speeds and accelerations observed in the lab. Their results also suggest that kangaroo rats might amplify their power when under attack by rattlesnakes via "elastic energy storage."

"Elastic energy storage is when the muscle stretches a tendon and then relaxes, allowing the tendon to recoil like an elastic band being released from the stretched position," Higham explained. "It's equivalent to a sling shot -- you can pull the sling shot slowly and it can be released very quickly. The kangaroo rat is likely using the tendons in its lower leg -- similar to our Achilles tendon -- to store energy and release it quickly, allowing it to jump quickly and evade the strike."

To collect data, the team radio-tracked rattlesnakes by implanting transmitters. Once the rattlesnake was in striking position, the team carried the filming equipment to the location of the rattlesnake (in the middle of the night) and set up the cameras around the snake. The team then waited (sometimes all night) for a kangaroo rat to come by for the snake to strike.

"We would watch the live view through a laptop quite far away and trigger the cameras when a strike occurred," Higham said.

Next, the researchers plan to expand the current work to other species of rattlesnake and kangaroo rat to explore the differences among species.

Video:


Story Source: University of California - Riverside. "Viper's strike quantified in nature for the first time: Research aims to understand factors that determine the success/failure of a strike or escape in predator-prey interactions." ScienceDaily. www.sciencedaily.com/releases/2017/01/170113085947.htm (accessed January 13, 2017).




Journal Reference:
Timothy E. Higham, Rulon W. Clark, Clint E. Collins, Malachi D. Whitford, Grace A. Freymiller. Rattlesnakes are extremely fast and variable when striking at kangaroo rats in nature: Three-dimensional high-speed kinematics at night. Scientific Reports, 2017; 7: 40412 DOI: 10.1038/srep40412

Abstract
Predation plays a central role in the lives of most organisms. Predators must find and subdue prey to survive and reproduce, whereas prey must avoid predators to do the same. The resultant antagonistic coevolution often leads to extreme adaptations in both parties. Few examples capture the imagination like a rapid strike from a venomous snake. However, almost nothing is known about strike performance of viperid snakes under natural conditions. We obtained high-speed (500 fps) three-dimensional video in the field (at night using infrared lights) of Mohave rattlesnakes (Crotalus scutulatus) attempting to capture Merriam’s kangaroo rats (Dipodomys merriami). Strikes occurred from a range of distances (4.6 to 20.6 cm), and rattlesnake performance was highly variable. Missed capture attempts resulted from both rapid escape maneuvers and poor strike accuracy. Maximum velocity and acceleration of some rattlesnake strikes fell within the range of reported laboratory values, but some far exceeded most observations. Thus, quantifying rapid predator-prey interactions in the wild will propel our understanding of animal performance.




Taipan
Mar 17 2016, 07:54 PM


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This new study records Crotalus scutulatus with a Max snake velocity of 3.5 ms−1!!

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Attached File Rattlesnakes_are_extremely_fast_and_variable_when_striking_at_kangaroo_rats_in_nature.pdf (620.1 KB)
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