Odatria The electronic newsletter of the Victorian Herpetological Society. Issue 20, December 2016 Recovering the Striped legless Lizard Limbless Locomotion: Sliding, sidewinding, saltation and more... Top 10 Weirdest, Wackiest Lizards. Cover shot: Has noted wildlife photographer and writer Michael Cermak been employing genetic engineering in tandem with evoking medieval incantations? Perhaps he has just acquired a new version of Photoshop... See you at the: 2017 VHS Reptile & Amphibian Expo. Melbourne Showgrounds Saturday 4th March 2017, 9am to 4pm. Special guest speakers: Prof. Bryan Fry & Joe Ball. Free entry for VHS members! Cover: Thorny Devil (Moloch( horridus) by Adam Sapiano.
Issue 20, December 2016 The Wrangler Writes. he VHS committee T would like to be on public record that it is not in any way associated with a certain licensed snake removalist in the western suburbs who is recently rumoured to have taken to wearing a red suit with white fur trim and insists on attempting to climb down chimneys with the aid of a large snake hook. We have received some great positive feedback on the new meeting venue, with a number of members commenting on the great facilities at the Anglers Tavern, and the convenient location. Although I was unable to attend the last meeting due to family illness, one member went out of his way to tell me that he thought Rex Neindorf s presentation was one of the best he had ever seen; thanks Rex! We continue to source the best possible speakers from around the country, so make sure you get along to meetings whenever you can. And whilst on the subject, we have secured the services of venom expert Prof. Bryan Fry and blue-tongue boffin Joe Ball for our expo in March 2017. Both will also be speaking at a special BBQ at the Anglers Tavern on the Friday night, so make sure you watch our website and Facebook page for further details. It will be an event not to miss! This issue of Odatria features a fantastic article on snake locomotion by Kit Prendergast Kit, you ve done it again! Don t forget to support our sponsors, Minibeasts and Karingal Veterinary Hospital, without which Odatria would not be possible. Lastly, have a happy and safe Xmas and a prosperous New Year. John McGrath 2016 VHS Office Bearers: President: Adam Sapiano Secretary: Kevin Welsh Treasurer: Shane Brodie Exec. Committee: John McGrath, Shane Robinson Odatria is published by the Victorian Herpetological Society Inc. copyright 2016 all rights reserved. Apart from any fair dealing, as permitted under the Copyright Act, no part may be reproduced or stored by any process without written permission. Uncredited photos are from the VHS archives. Photos published remain the property of both the VHS and the respective authors and are subject to full copyright and all rights are reserved. Views or opinions expressed are entirely those of the relevant authors and should not necessarily be taken to represent the VHS. Correspondence: vhs@optusnet.com.au or the editor: j_mcg@tpg.com.au What you lookin at? Page 3
Odatria Limbless Locomotion. Sliding, sidewinding, saltation and more: how serpents have adapted to life without legs. Zoologist and conservationbiologist Kit Prendergast tackles the science of slithering... here are approximately 3,400 extant T species of snakes, having a cosmopolitan distribution and occupying a huge range of habitats. The evolutionary success of this group is due in part to their incredible locomotory abilities. An obvious diagnostic feature of snakes is their state of leglessness : the earliest snakes possessed tiny hind limbs, however through the course of evolution these were lost. Early-diverging snakes (e.g. boas and pythons) still retain vestiges of the pelvic girdle and hind limbs, however these are functionless. Natural selection was responsible for the loss of limbs, so snakes body plan must confer adaptive benefits. Nevertheless, being legless poses significant chal- lenges in terms of locomotion. Stem snakes (the earliest snakes identified from the fossil record) evolved approximately 125 million years ago, and crown snakes (modern snakes) evolved about 105 million years ago. Both originated on land (rather than in aquatic settings), and snakes distinctive long, limbless body plan appears to have evolved as an adaptation for burrowing. This hypothesis is supported by the analysis of fossils (Dinilysia patagonica) linked to ancestral snakes; these possess a unique inner ear structure shared by extant burrowing snakes and lizards, but which is absent in snakes living in water or above ground. Furthermore, all extant snakes have an elongate body with a relatively short tail - a trait they share with burrowing lizards. Like ancestral fish and then the first land-based tetrapods, ancestral reptiles inherited a form of locomotion based on alternating lateral undulations of the body. Most snakes retain this pattern, however the lack of legs and highly undulatory nature of movement places very high twisting forces on their vertebral columns. To cope, snakes have two additional sets of zygapophyses - paired bony processes that interlock each vertebra with the vertebrae above and below. These help limit torsion, without dramatically restricting the lateral bending of the vertebral column. Page 4
Issue 20, December 2016 But moving on land using lateral undulations is much harder than in water. Tetrapods use their limbs to generate thrust. The solid framework of bones and muscles functions as a system of levers, transmitting force to the substrate and powering the animals along. Without limbs, snakes lack these propulsive forces. Instead, their anatomical basis for movement involves their long backbones (comprising several hundred vertebrae) and complex, multisegmented muscle chains and tendons. On surfaces with some texture, snakes scales create passive friction, with less directed towards the front than the back, enabling forwards movement. The amount of friction can be actively adjusted by modifying the angle between the scales and the substrate too much would impede movement. Six modes of snake locomotion are recognised: lateral undulation, sidewinding, concertina, rectilinear, slide-pushing and saltation. Several different modes may be employed simultaneously at different points along the snake s body. Species differ in their tendency to use a particular mode, and this is associated with differences in body plan and adaptations to the substrate they frequently encounter. Lateral undulation characteristically called serpentine movement is the most widespread mode of locomotion. Concertina locomotion and sidewinding are also common, and are used when there are insufficient substrate projections necessary for lateral undulations. All generate propulsive forces through laterally flexing the vertebral column by contracting axial muscles. During lateral undulations, horizontal waves travel down alternate sides of the body. Although limbed reptiles also often move with lateral undulations, snakes differ because, lacking limbs to provide fixed points for generating propulsive force, they instead rely on moving their body continuously to push past fixed irregularities (e.g. stones, grass tussocks, bumps) in the environment. Despite each point generating a sideways force, the lateral forces on opposite sides of the body cancel out, leaving a net rearward force which propels the snake forwards. Studies have revealed that laterallyundulating snakes move by continuous posterior propagation of alternating unilateral muscle activity, with limited contribution from the tail. Whilst this form of locomotion works well on rugged substrates, it gets a snake nowhere on a smooth surface! SIX modes of SNAKE LOCOMOTION LOCOMOTION are recognised. Sidewinding is effective on low-friction, shifting substrates like sand or mud. Watching a snake sidewinding is quite bewildering! Despite the impression The mechanics of movement. Pythons and pythons still retain vestiges of the pelvic girdle and hind limbs. All images by Kit Prendergast. Page 5
Odatria Limbless Locomotion (cont). that the creature is throwing loops of its body in all directions, sidewinding actually involves a highlycomplex locomotory pattern in which sections of the body are alternatively lifted, moved forward and then set down. During any sequence, the body is in static contact with the ground at two points. Sidewinding can occur in a left or right-handed manner and leaves a characteristic series of separate, parallel, J-shaped tracks, each orientated at an angle to the direction of travel. The tracks are about as long as the snake s body. Sidewinding is exemplified by the snake whose common name alludes to its preferred method of locomotion: the Sidewinder (Crotalus cerastes). By varying the proportion of its body that is in contact with the sand, this small, venomous pit viper can ascend steep, sandy dunes without slipping a feat that related pit vipers cannot accomplish. Other desert snakes that often use sidewinding include Asian and African vipers, Horned Adders (Bitis caudalis) and Peringuey's Adder (Bitis peringueyi). Specialised sidewinders travel with considerable speed, attaining forward velocities of 2.0 total lengths per second. Increased velocity can be achieved by using sidewinding on sand, and sidewinders have been shown to switch from pure lateral undulations, to lateral undulations with sidewinding, to pure sidewinding, with incremental increases in speed. But sidewinding is not confined to desert-dwelling snakes, and is also utilised effectively by other species to traverse slippery substrates, such as slick, slimy mudflats (e.g. the Dogfaced Water Snake, Cerberus rynchops). In fact, sidewinding can be induced in many snakes, although they are often reluctant to do so. Not only is sidewinding adaptive for travelling on yielding or slippery surfaces, but by preventing slippage at points of contact, it confers energetic advantages relative to all other forms of snake locomotion. Concertina locomotion involves the anterior region of the body remaining stationary while the posterior end is drawn up behind it in a series of tight curves. The posterior end then provides a region of static contact, enabling the anterior region to be extended forwards. The process is then repeated. Concertina locomotion is used on surfaces that are unsuitable for lateral undulations, but where enough static friction exists to prevent backwards slippage. This form of locomotion is most commonly used when crawling through burrows or tubes - lateral undulations are restricted, yet snakes can brace their bodies against the walls. Concertina locomotion is not for animals in a hurry. Banded Water Snakes (Nerodia fasciata) travel only 0.05 total lengths per second using this form of locomotion, but can achieve 1.88 total lengths per second using lateral Page 6
Issue 20, December 2016 undulations. It also requires a lot of energy; Eastern Racers (Coluber constrictor) use seven times more energy when employing concertina locomotion, compared with lateral undulation. Rectilinear locomotion differs from other forms of snake locomotion in that it does not rely on alternating contractions of the lateral muscles along the trunk. Rather, both of the lateral muscle masses act in synchrony, sequentially contracting and relaxing, which draws the body forward in a fairly straight line. Rectilinear locomotion mainly involves two series of muscles which run from the ribs to the skin of the ventral surface. The costocutaneous superior muscles pull the skin forwards relative to the ribs; the ventral scales then anchor the body to the substrate. Next, the costocutaneous inferior muscles pull the ribs - along with the vertebral column, axial muscles, and viscera - forward relative to the stationary ventral skin. Several waves of these symmetrical contractions pass down the body at any one time, so that a number of points of stationary contact are established. This creates a bizarre effect in which it appears that the ventrolateral skin is crawling on its own, whilst the dorsal skin moves at a nearly even rate! Rectilinear locomotion is most common in large snakes like boids and vipers, however all snakes are likely capable of using this mode of locomotion. Snakes sometimes use slide-pushing when travelling on low-friction substrates. Although similar to lateral undulation in that it also involves alternating waves of body motion, in slide-pushing there are no fixed points in the physical environment to generate forces pushing the body forwards. Instead, the snake moves its body incredibly quickly, propagating waves so rapidly that enough sliding friction is generated to propel it forwards. This form of locomotion isn t very efficient despite all that wriggling, slidepushing snakes appear to be simply flailing about, and only progress gradually. Finally, saltation is a rare, pretty extreme form of locomotion employed by the Horned Adder, a short, heavy-bodied viper from southern Africa. The snake rapidly straightens its body from anterior to posterior, which actually causes it to be lifted entirely off the substrate. Only very small individuals move in this manner. Unlimited by a legless lifestyle. Climbing steep surfaces poses challenges for any animal: the entire body weight must be continually lifted, in addition to preventing slipping (and potentially fatal consequences). Despite lacking grasping limbs, claws or the adhesive toe pads present in other arboreal animals, snakes from diverse lineages have independently evolved to be remarkable climbers. Snakes use muscular gripping forces to climb, as do primates, but have a distinct advantage because their entire body can be used (rather than just the hands, feet and sometimes the tail), enabling them to grip branches spanning a wide range of diameters. If snakes are climbing rough, relatively horizontal surfaces, with adequatelyspaced irregularities, they can shimmy up without needing to use their body for additional grip. But when climbing smooth, steep, cylindrical structures, snakes use a type of concertina locomotion involving periodic static gripping: looping the body around a branch one to three times, stretching forwards, then looping around again and dragging the lower part of the body up behind. This frictiongripping concertina locomotion prevents slipping, but requires the application Although most common in large species such as boids and vipers, all snakes are likely capable of rectilinear locomotion. In this EXTREME form of locomotion, the snake s body is lifted ENTIRELY OFF THE SUBSTRATE. Page 7
Odatria Limbless Locomotion (cont). of considerable force, and involves a lot of stopstarting. Energy expenditure is high, and progress is relatively slow. Given the energetic cost of using muscular forces to grip inclined, cylindrical surfaces, and that snakes have considerable control over the size and orientation of their grip, one would expect some economisation in that a minimum amount of exertion would be used. Yet a study in 2014 found that this was not the case; rather, snakes have a policy of safety first and will grip the substrate with a safety factor often exceeding three. Of the five species examined, Boa Constrictors, the species least specialised for an arboreal existence, were the most safety conscious, with safety factors of five recorded. Nevertheless, the extra force may represent an overall energy saving, because it minimises the risk of slipping backwards, which may be energetically costly given that any Arboreal snakes possess specialised belly scales that form a ventrolateral keel. ground lost must be recovered. BROWN TREE SNAKES have In Guam, BROWN become a nuisance, climbing power poles and causing ELECTRICAL OUTAGES and SHORT CIRCUITS! The vine snakes, a group of superb tree climbers comprising numerous colubrid lineages, climb using gapbridging, and can cantilever up to half their body into open space until their head reaches another branch. Adaptations for gapbridging include slender, laterallycompressed bodies and large vertebral scales that prevent the body from bending dorsoventrally. Typically, specialist tree-climbing snakes have slender bodies and relatively long, prehensile tails for coiling around branches and providing anchorage as they extend their bodies forwards during concertina locomotion. Arboreal snakes also have belly scales which span the entire width of the body. On each side there is a notch, creating a fold where the belly scales meet the smaller dorsal scales, and forming a ventrolateral keel. This allows such snakes to modify their tubular shape so that in cross section they are flat across the bottom, and curved above. The ventrolateral keel along with the overlapping belly scales are highly effective at grasping irregularities. These snakes are therefore able to scale steep gradients despite lacking supporting structures other climbing animals possess. The ventrolateral keel is present but less developed in snakes that occasionally climb (e.g. Corn Snakes), but is lacking in ground-dwelling snakes, which are round in cross section and must expend considerably greater energy climbing, as they maintain a tight grip whilst slowly inching their way upward. Brown Tree Snakes (Boiga irregularis) are elite climbers. The exceptional climbing ability of this intro- Page 8
Issue 20, December 2016 duced species has enabled it to wreak havoc on Guam, decimating the native birdlife by climbing into nests and eating birds and their offspring. The snakes are also causing a nuisance by climbing power poles, causing electrical outages and short circuits! Amazingly, snakes of the genus Chrysopelea are also capable of gliding between trees. This is not a kamikaze free fall! Upon reaching the end of a branch, the snake makes a J-shaped bend and, after selecting a destination, leans forwards at the level of inclination required to control its flight path. It then thrusts itself up and away from the branch, and by spreading the ribs and broadening the body to create a deeply concave ventral surface, effectively creates a pseudo-wing which generates lift. Continual serpentine movements are made during flight, which stabilises direction in midair and facilitates safe landing. Chrysopelea species show remarkable control, manoeuvring to avoid obstacles when airborne, and can glide for up to 100 metres! Gliding saves energy, allows a greater distance to be traversed in a shorter amount of time, and means the snakes do not have to be exposed to ground-based predators. Some snakes have evolved highly-modified bodies as adaptations to an exclusively fossorial lifestyle, as exemplified by the earlydiverging clade Scolecophidia, comprising typhlopids (blindsnakes), leptotyphlopids (threadsnakes) and anomalepidids (early blindsnakes). To help burrow through the substrate, these small snakes have thin, cylindrical bodies, blunted heads, highlyreduced eyes and short tails. To reduce friction and repel attacks from aggressive insects that abound underground, they have very thick, smooth, overlapping scales. The snake body plan can also be considered to be pre -adapted for an aquatic lifestyle, given that snakes have invaded fresh water and marine environments multiple times. Independent invasions of the ocean occurred in the ancestors of acrochordids, homalopsines, natricines, hydrophiids, and laticaudids. As a result of their long, thin physique, snakes Sea snakes LUNGS evolved a single (right), elongated lung, providing a natural buoyancy and flotation device. Sea snakes lungs have been further modified to increase buoyancy and in hydrophiines the lung extends to occupy up to 100% of the trunk. Snakes moving through water employ a swimming style resembling that of long, thin fish, known as anguilliform locomotion, in which alternative waves pass down the body, propelling the animal forwards. The lateral undulation inherited from their terrestrial ancestors formed a good basis for this technique, however the biomechanics are very different. Unlike the terrestrial application, where force is applied at fixed points and the waves travelling down the body dampen towards the rear, the regular waves swimming snakes use increase in amplitude posteriorly. And in terrestrial lateral undulation, the propulsive force is generated by lateral surfaces of the body pushing against irregularities in the substrate, whereas in swimming, snakes move forward by their movement accelerating portions of the surrounding water. As a further adaption for swimming, aquatic snakes evolved features for increasing the surface area against which their body pushes against the water. LUNGS have been modified to increase buoyancy, and can OCCUPY OCCUPY 100% of the TRUNK. Sea snakes (hydrophiids and laticaudids) have laterally-compressed, paddlelike tails which generate considerable lift. Swimming snakes also are highly streamlined, with reduced ventral scutes and small, narrow heads not demarcated from the body. It may be that the already streamlined, buoyant bodies of snakes explains why hydrophiines have adapted to an exclusively marine lifestyle; despite lizards having a higher diversity than snakes (5,600 species Page 9
Odatria Limbless Locomotion (cont). Juvenile snakes ability to OPTIMISE their locomotory abilities according to habitat is HIGHLY ADAPTIVE. versus 3,400), there are no completely marine lizards. Various snakes move on both land and water; for example, Australian Tiger Snakes (Notochis scutatus) often forage in water. Depending on the habitat baby snakes experience early in life - from areas lacking any bodies of water, to permanently swampy habitats - they exhibit different locomotory abilities. Different constraints on optimal morphology and physiology create a trade-off between locomoting with maximum efficiency on land versus water, such that improved swimming/diving abilities correspond with reduced terrestrial performance. The ability for juvenile snakes to optimize their locomotory abilities according to the habitat they grow up in is highly adaptive; it means their bodies are matched to the environment they will live in. This plasticity may also have pre-adapted ancestors of today s marine snakes to an exclusive aquatic environment, since enhanced aquatic locomotion by offspring growing up in watery habitats with the associated reduced ability to locomote on land would have favoured spending more time in water, driving a progression of increasing adaptation for a fully-aquatic existence. The trade-off between aquatic and terrestrial locomotion is illustrated by amphibious sea kraits (family Lauticaudidae), which forage in the ocean, but return to land to shed, digest prey, court, mate, and lay eggs. Laticauda colubrina spends up to half its time on land, and must ascend steep-walled, rocky cliffs. The selective pressure to retain effective terrestrial locomotion means that this species is heavier-bodied and stronger than more aquatic sea kraits like L. laticuadata. Scientific tests have confirmed the superior cliff-climbing abilities of L. colubrina, however, The author indulging in some slithery science. this species speed of terrestrial locomotion is nevertheless reduced by 80%, respective to terrestrial elapids, due to adaptations for swimming. Hydrophiids the most specialized sea snakes are virtually unable to crawl on land. Scientists are interested in studying snakes locomotory abilities as inspiration for designing search and rescue robots that can scale buildings and cover various substrates without having appendages that could get caught. Snake s cylindrical, flexible bodies are perfect for squeezing through tight spaces, climbing up/ through pipes, and traversing all types of terrain. Page 10
Issue 20, December 2016 Who am I? ingers on your buzzers for the chance of a pick from the board! F I look much like an agamid and was classified as such for more than 15 years, but in reality I am quite unique. Like some lizards, I can shed my tail as a defence mechanism, which will then regrow but I m not actually a lizard! I reach sexual maturity at about 15 years; on average females only breed once every four years, and my lifespan is estimated to be up to 100 years. I possess a rudimentary third eye on the top of my skull which may be sensitive to light. Native to New Zealand, my heart rate is a mere eight beats per minute. The sole surviving member of the order Rynchocephalia, I have remained virtually unchanged for 200 million years. I am the... (Answer in next issue. Last time: I am the Pygmy Blue-tongue.)???? Herpetofunnies! Q: What do you call a snake that builds things? A: A boa constructor! Q: How do you measure a snake? A: In inches. They don't have any feet! Q: What do you call a snake who works for the government? A: A civil serpent! source: http://www.jokes4us.com/animaljokes/snakejokes.html Page 11
Odatria Kevin Welsh s Top 10! Weirdest, Wackiest Lizards! W ith the assistance of Wonderlists, here are ten of the coolest, weirdest lizards in the world large and small. 10. Miniature Chameleons. The leaf chameleons (Brookesia spp.) are endemic to Madagascar, where they are often found beautifully camouflaged amongst leaf litter. The smallest species, Brookesia micra, was discovered sometime between 2003 and 2007 on the small islet of Nosy Hara. It attains an adult length of just 29mm, which also makes it one of the world s smallest reptiles. 9. The Armadillo Girdled Lizard. This strange-looking species is found in South Africa and grows to an average snout to vent length of 7.5-9cm. Also known as the Golden Armadillo Lizard due to its colouration, it lives in rock crevices and cracks, and if threatened, will curl up into a ball, taking its tail in its mouth; it is then protected by the thick, squarish scales on its back and spines on its tail. Females are also unusual in that they may feed their young. 8. Frilled Lizard. Thanks to the large, colourful ruff of skin around its neck, the iconic Frilled Lizard of northern Australia and southern New Guinea is able to put on one of the most striking displays in the reptile world. This consists of spreading the expansive orange or red frill, gaping to reveal the bright yellow mouth, raising the body, and sometimes also holding the tail above the body. Frilled Lizards are capable of bipedal locomotion but spend most of their time in the trees. Page 12
Issue 20, December 2016 7. Fantastic Leaf-tailed Gecko. Also called the Satanic Leaf-tailed Gecko, Uroplatus phantasticus has an uncanny resemblance to withered or dried leaves. It grows to a maximum length of about 15cm and is also endemic to the island of Madagascar. 6. Two-headed Bobtail Lizard. Whatever you want to call it, the shingleback, bobtail, pinecone lizard, or stumpy-tail certainly qualifies as one of the weirdest of lizards. As if it isn t difficult enough to tell which is the pointy end, here is one with two heads! 5. Flying Geckos. Flying geckos don t exactly fly, they glide up to 60m! A number of Southeast Asian geckos are equipped with anatomical features such as elaborate digital webbing and skin flaps, and flattened bodies and tails. When airborne, with all membranes extended, these creatures give the impression of wearing miniature wingsuits. Page 13
Odatria Top 10! (cont.). 4. Sailfin Water Lizard. Endemic to the Philippines, these unique creatures may reach up to a metre in length. They are typically found near rivers and even have flattened toes that enable them to run across water. Males possess exaggerated dorsal crests and exhibit hues of violet, red or blue. 3. Galapagos Land Iguana. Charles Darwin called Galapagos Land Iguanas, ugly animals, of a yellowish orange beneath, and of a brownish-red colour above: from their low facial angle they have a singularly stupid appearance. They grow to 1-1.5m, weigh about 11kg and bask on volcanic rocks during the day, retiring to burrows at night to conserve heat. Galapagos Land Iguanas are primarily herbivorous and can live for up to 60 years. They have a symbiotic relationship with birds, which remove external parasites from the iguanas. Page 14
Issue 20, December 2016 2. Marine Iguana. Marine Iguanas are also natives of the Galapagos Archipelago; Darwin christened them imps of darkness, and described them as disgusting clumsy Lizards...as black as the porous rocks over which they crawl. Unique among modern lizards, they forage exclusively in the cold sea, scraping algae off rocks with their flat jaws. Marine Iguanas can grow to a snout to vent length of 34cm and weigh up to 13kg. They possess a laterally flattened tail for propulsion and long, strong claws to hold onto rocks in the currents. Their dark colour enables them to rapidly absorb heat after emerging from the water. Excess salt is filtered by a nasal gland and excreted from 1. Komodo Dragon. Inhabiting the Indonesian islands of Komodo, Rinca, Flores, Gili Motang and Padar, the Komodo Dragon is the largest living species of lizard, growing to over 3m and weighing up to 70kg. These giant varanids often prey upon deer but also hunt and ambush other mammals, birds and invertebrates and consume considerable amounts of carrion. They have venomous saliva that includes an anticoagulant and have been known to attack humans! Page 15
Odatria Monitoring the past. In this offering from 2002, Mike Swan details Melbourne Zoo s programme to assist the Striped Legless Lizard. Page 16
Issue 20, December 2016 If there are any particular articles that you would like to see reproduced, or you have one that you would like to share, please contact the editor. Page 17
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