User Tools

Site Tools


australia:snakes

Australian snakes

Introduction

  • most of the world's top 10 venomous snakes reside in Australia!
  • snakes in Australia are a protected species!
  • the venomous snakes are Elapids of which there are 90 terrestrial species which account for 57% of all terrestrial species in Australia, and the non-venomous pythons 1)
  • Australian is home to over 130 species of the 320+ known species of Elapid snakes (including sea snakes)
  • all Australians and travelers to the Australian bush or coastal regions should know how to avoid and how to survive a snake bite.
  • snakes eat frogs, eggs, small mammals, lizards and even other snakes
  • snakes are active when their body temperatures are between 28 and 31 °C and thus they thermoregulate by basking in warm sunny spots in the cool early morning (eg. on your pathway) and rest in shade in the middle of hot days, and may reduce their activity in hot dry weather in late summer and autumn
  • the only time two snakes are in the same place is during courtship and mating. Otherwise the larger snake will usually kill and eat the smaller one
  • snakes can hear low pitch sounds and feel vibrations but have trouble hearing higher pitched sounds
  • snakes generally will try to make their way to their preferred escape route and last known safe haven, but sometimes they make poor choices when threatened and the eye sight is relatively poor - if a human is between them and their safe haven they may adopt a defensive raised posture to try to signal to you to get out of their way and then they will approach their safe haven which may appear they are chasing you but they are not!
  • if you approach and harass them they respond with a strike and a bite, although, fortunately, most are dry bites which do not envenomate - never try to catch a snake unless you are trained to do so - call a snake catcher!
  • snakes like to hide under shelters such as sheets of iron roofing, concrete slabs, piles of wood or rocks, etc - take great care when lifting these up.

Evolution

  • snakes evolved from lizards c120-150mya
    • NB. “goannas” (monitor lizards) evolved 90mya in the Nth Hemisphere and migrated to Australia 15mya where they evolved into 28 species
  • Pythons (lay eggs, have a pelvic remnant, two lungs, and did not make it to America until recently) diverged from Boa (give birth to live young) in the Cretaceous period and migrated from Asia to Australia and New Guinea via Wallacea c8-14mya
    • ancestors of Morelia split from the Python tree c35mya 2)
      • Morelia sp evolved 20-22mya
        • Morelia spilota evolved c8mya
  • Elapids (including sea snakes) appear to have evolved from an Asian ancestor 38mya and then rapidly diversified into:
    • coral snakes (30-25mya)
    • Afro-Asian clade of cobras and mambas (30-25mya)
    • Australasian clade including Bungarus (Kraits) and Elapsoidea (African garter snakes) (Hydrophiinae) 25mya
      • semi-aquatic sea kraits (Laticauda)
      • terrestrial Australian Elapid snakes
        • Pseudechis sp 17.5mya
        • two burrowing lineages (Vermicella+Neelaps, Simoselaps+Brachyurophis) 17mya
        • Pseudonaja and Oxyuranus ancestor 14mya
      • viviparous sea snake (Hydrophiini) ancestor 16mya
        • Australepis and Notechis ancestor 12mya
        • Hydrophis 8mya
  • all continents became colonised with snakes by 30-25mya
  • it would seem the Australian elapids are all fairly closely related to each other as a relatively snake-free Australian continent was colonised only 25 mya 3)
  • morphological and biochemical data have suggested a close relationship between Australian terrestrial proteroglyphs and hydrophiid sea snakes
  • prey preference drives the evolution of venom composition and toxicity in snakes

Victorian snakes

Tiger snake

  • Notechis sp
  • 17% of snakebites in Australia
  • these are also the main snakes living in Tasmania (where a sub species, the Black Tiger snake also resides)
  • relatively poor eyesight and slower moving than a brown and thus more likely to be trodden upon
  • in Victoria, the species is the Mainland Tiger Snake (Notechis scutatis) which usually grows to 0.9m but can grow to 2m and prefers coastal areas and wetlands
  • these snakes flatten their body and raise their heads if threatened

Common Eastern Brown snake

  • Pseudonaja textilis - a fast (can outpace a human running) and aggressive snake with good eyesight
  • the second-most venomous terrestrial snake in the world
  • grows to 1.5m and sometimes to 2m
  • found along the east coast of Australia from Malanda in Qld down to Victoria and across to Yorke Peninsula in Sth Australia. Disjunct populations occur elsewhere such as NT.
  • tends to prefer drier areas such as sclerophyll forests, coastal heaths, farmlands (especially as they prefer to eat rodents), etc
  • has two phases of threat display:
    • partial: raises front of body partly off the ground and flattens neck
    • full: rises up vertically high off the ground, coiling its neck into an S shape, and opening its mouth
  • this means, unlike most other snakes, these snakes can bite the upper thigh when standing, but fortunately most bites do not result in envenomation
  • walking in undisturbed areas on cool days in September and October risks running into courting male snakes, that would not notice people until close as they were preoccupied with mating
  • snakes will generally move away early when they detect humans, and they can detect them better if they are wearing dark clothing and approaching quickly and noisily, and are less able to detect when people are moving slowly, especially on a cloudy, windy day

Red-bellied Black snake

  • Pseudechis porphyriacus “false viper”
  • native to the east coast of Australia as far north as Gladstone in Qld
  • in Victoria it is mainly in the south, east, central parts of Victoria but extends to Sth Australia along the Murray River
  • account for 16% of snake bites in Australia but no deaths
  • it is the most commonly reported species responsible for envenomed dogs in NSW
  • not aggressive, less venomous, usually within 100m of a water body, average length 1.25m but can grow to 2.5m
  • there are related species in the Atherton Tablelands in Qld (Pseudechis porphyriacus eipperi ) and another in southeastern South Australia (Pseudechis porphyriacus rentoni )

Copperhead snake

  • a shy snake which rarely bite humans unless provoked
  • Common Lowlands Copperhead Australeps superbus
    • length usually reaches 1.75m
    • common in southern Victoria and in Tasmania
    • these are the only snakes on Philip Island
  • Alpine or Highlands Copperhead Australeps ramsayi
    • grows to 1.25m and lives near streams in northern Victoria and southern NSW alpine regions
  • Pygmy Copperhead Australeps labialis
    • confined to Sth Australia

non-venomous pythons

  • mainly found in the Wangaratta and eastern Gippsland regions
  • Carpet Python Morelia spilota metcalfei - mainly nocturnal; northern areas;
  • Diamond Python Morelia spilota spilota - non-venomous; coastal heaths of far east Gippsland

other snakes

  • Little Whip snake Rhinoplocephalus flagellum
  • snakes confined mainly to north-western regions of Victoria (eg. Mallee):
    • Western Brown Snake Pseudonaja nuchalis - fast, aggressive
    • Master's snake Drysdalia mastersii - mainly Mallee
    • Mitchell's Short-tailed snake Rhinoplocephalus nigriceps - mainly Mallee & north-central areas
    • Bardick Echiopsis curta - mallee region
    • Port Lincoln snake Rhinoplocephalus spectabilis
    • Red naped snake Furina diadema - rare; usually assoc. with termite mounds
    • Yellow-faced Whipsnake Demansia psammophis - fast snake; Murray River;
  • snakes confined mainly to northern Victoria:
    • Curl Snake Suta Suta - mainly in the Loddon, Avoca and Murray rivers region
    • Bandy Bandy snake Vermicella annulata - rarely seen snake in northern areas; nocturnal;
    • Blind snakes Ramphotyphlops spp - rarely seen snake in northern areas; non-venomous; nocturnal;
  • snakes confined mainly to south-eastern Victoria:
    • White-lipped snake Drysdalia coronoides - eastern suburbs Melbourne & southern forests but rarely seen
    • Small-eyed snake Cryptophis nigrescens - warm dry forests of south-eastern Victoria
australia/snakes.txt · Last modified: 2019/02/11 14:01 by gary1