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Timber Rattlesnake (Crotalus horridus)

The magnificent timber rattlesnake (Crotalus horridus) is a venomous pit viper which lives throughout the populated northeastern portion of the United States of America from Texas to New England.  Ferrebeekeeper has considerable affection for the dangerous reptile (at an appropriate distance, of course!) and has already referenced the timber rattler as a metaphor for national liberty and, strangely, as a point of comparison for a large sports venue.  But timber rattlesnakes are so much more.  They were one of the first new world animals to utterly fascinate and horrify European colonizers. In the colonial period a serious rattlesnake bite was a death sentence (although we now have anti-venom) but the original natural scientists did not appreciate how complicated and remarkable the snakes were in other aspects.

As I write this, it is November and the rattlesnakes are all abed for the winter.  Because they live in areas with harsh winters, timber rattlesnakes spend more than 7 months a year in hibernation.  Large numbers will nest together in a community den—sometimes together with other snakes such as blacksnakes and copperheads.  The den is usually a rocky chasm which extends deep beneath the frost line, and rattlesnakes may travel many miles to reach their hibernation den (a bi-annual journey which puts the snakes at great risk from predators and from cars).

Because of their large and diverse territory, timber rattlesnakes come in different sizes, colorations, and even have different venom types.  The average timber rattlesnake grows to 100 cm (39 in) long and weighs between a half kilo and a kilogram (1 to 2 pounds).  Much larger specimens are known (although there is considerable ridiculous dispute about the upper ranges of rattlesnake size).  Female timer rattlesnakes are viviparous although, unlike mammals, rattelsankes protect their eggs within their bodies until they hatch.  Rattlesnakes give birth to litters of 6-10 fully formed, fully poisonous little baby snakes, but they can only reproduce every few years since the experience is very hard on them.

Like catfishes, timber rattlesnakes have senses which we do not possess.  Pit vipers are so named because they have nostril like spots (pits!) on the side of the head which they use to perceive infrared electromagnetic radiation. These pits are quite sensitive and act as third eyes.  Snakes (and many other animals) also have special auxiliary olfactory sense organs called Jacobson’s organs which are extremely sensitive to various smells/tastes.  Snakes characteristically pick up chemical traces with their tongues and waft these smells before their Jacobson’s organs in the characteristic tongue-flicking which is such a trademark.

Of course rattlesnakes are not just sensitive—they are also expressive.  Among all other snakes they are distinctive in that they have a specialized structure at the end of their tail for making a warning noise. Rattlesnake rattles consists of hollow button-like segments which produce a distinctive buzzing when the snakes vibrate their tails.  As a rattlesnake sheds her skin (every few months), she adds a new button to her tail.  Rattles however are not perfect records of how many times snakes have shed their skin—sometimes buttons get knocked off, or just become brittle and fall away.  The rattle has a high frequency and varies in loudness between 60-80 decibels from a distance of one meter (which falls somewhere between the noise level of an animated conversation and a garbage disposal).  Ironically, the rattlesnakes themselves are deaf.

Timber Rattlesnakes can be masters of camouflage

The venom of timber rattlesnakes varies in toxicity depending on the subspecies, but the most toxic rattlesnakes are extremely venomous.  Type A venom is a neurotoxin whereas type B venom is hemorrhagic and proteolytic (which is to say it causes bleeding and breaks down fundamental body proteins).  Type C venom is largely harmless.  In Arkansas and Louisiana, timeber rattlesnakes are particularly dangerous because cross-breeding has resulted in snakes which have type AB venom (yikes!). To a lesser extent rattlesnake venom also contains esoteric myotoxins which rapidly kill muscle tissues.  This deadly cocktail of different venoms is of great interest to pharmacologists who continue to study the various toxic proteins to tease out potential medicines.

watch?v=ZIrQet2LPUg

Fortunately timber rattlesnakes are good-natured and do not generally bite without much posturing, rattling, hissing, and feinting.  They keep their retractable fangs folded up in a mouth sheath when not in use and they are capable of varying the amount of venom they inject based on how they are feeling.  It is best not to antagonize rattlesnakes lest they abandon their amiable disposition.

Timber rattlesnakes are gifted ambush predators which particularly prey on small mammals such as squirrels, chipmunks, mice, and other rodents, but they also eat amphibians and birds.  In turn rattlesnakes  are preyed on by owls, hawks, bobcats, foxes, crows, skunks, and even turkeys! Rattlesnakes are an important part of the woodland ecosystem, but they face serious threats from habitat loss and traffic (cars being indifferent to the protective poison of snakes).

C. horridus eating a chipmunk by unhinging its jaw (Photo taken by Kevin Ostanek)

Not only are many rattlesnakes killed by traffic, they must also face persecution. Many are killed by angry villagers carrying torches and pitchforks.  Gawping Texans take this to a particular extreme and organize great “rattlesnake round-ups” where huge numbers of rattlesnakes are wantonly tormented and killed for no particular reason (except perhaps to demonstrate a hatred of the world and its creatures).  This is particularly sad since rattlesnakes, like whales, or elephants (or ourselves) are k-selected animals.  They live long but reproduce slowly, which makes them especially vulnerable to population crashes.

If, by some appalling circumstance, you have read this far while a timber rattlesnake sits nearby buzzing its tail, you should run away from the snake!  Do not attempt to molest it.  If you feel threatened, call animal control.  The timber rattlesnake is already vanishing from great expanses of its territory.  It would be a shame if this beautiful and fearsome serpent were to slip away from the earth.

Timber Rattlesnake by Hazel Galloway

Woodblock prints of ages past show giant octopuses ripping apart boats and feasting on sailors like popcorn.  These artifacts of ancient sea-lore make for rousing images, but they are quite wrong:  octopuses are fierce and cunning hunters but they present little danger to humans—with a noteworthy exception.  The truly dangerous octopuses are not giant monsters (perhaps the artists of yesteryear were thinking of the mighty giant squid?) but rather tiny jewel-like beauties from the genus Hapalochlaena which includes only three or four species.  Known as blue-ring octopuses the tiny creatures swim in tide pools and shallows of the Indo-Pacific Ocean from Japan down to Australia (where they are most prevalent).  Blue-ringed octopuses live on shrimp, crabs, minnows, and horseshoe crabs.  They are tremendous hunters who use camouflage, stealth, and guile to catch their prey.  However, these tools pale before their greatest weapon: the little octopuses are among the most poisonous creatures on planet Earth.

(photo by Aluki from Flickr)

Like the flamboyant cuttlefish, the blue-ringed octopus does not like to bite without giving warning but advertises its toxicity with vivid coloration.  The octopus can conceal itself with tremendous prowess however, as soon as it becomes aware of a predator or some other threat, it dials up its coloration changing from muted reef tones to brilliant yellow with iridescent blue rings.  If you see something like this in the ocean, for heaven’s sake don’t touch it.  The octopus’s warning colors let ocean predators know to leave it alone but immediately attract humankind’s magpie urge to grab shiny things.  Although blue-ringed octopuses are good natured and have been known not to bite people who were provoking them rather intensely, their bites have caused more than seventy recorded fatalities in Australia. The octopus has a tiny beak and often a victim does not realize they have been bitten until they began to fall into paralysis and their respiration starts to fail.

Argh, I said don't touch it

The venom of the blue ringed octopus is a complicated pharmacological cocktail which includes tetrodotoxin, 5-hydroxytryptamine, hyaluronidase, tyramine, histamine, tryptamine, octopamine, taurine, acetylcholine, and dopamine. The most active ingredient tetrodotoxin blocks the sodium channels which conducting sodium ions (Na+) through a cell’s plasma membrane.  This causes total paralysis for the octopus victim, however if clever and persistent rescuers are present at the time of the bite they can rescue the unfortunate soul with continuous artificial respiration.  This is no small matter as bite victims are often rendered completely unresponsive by the paralytic victim.  Although completely conscious they are unable to communicate in any way or even breathe.  If artificial respiration is initiated immediately and continued until the body can metabolize and eliminate the toxin, bite victims can survive (although it sounds like rather an ordeal).

Blue ringed octopuses are tender and solicitous mothers.  The mother octopus lays a clutch of approximately 50 eggs in autumn which she incubates beneath her arms for about six months (during which time she is unable to eat).  When the eggs hatch, the mother octopus dies. The baby octopuses reach sexual maturity in about a year.  Despite their cleverness and beauty, the animals are as ephemeral as they are deadly.

Under its mother's watchful eye a baby southern blue-ringed octopus (Hapalochlaena maculosa) emerges from its egg.

Poison is very common in the animal kingdom (and throughout the other kingdoms of life) both as a means of defense and as a weapon for hunting, however only a tiny handful of mammals are poisonous.  A few shrews have mildly venomous bites.  The European mole has a toxin in its saliva which can send earthworms into a coma (allowing it to store them in the larder for later).  The Solenodon, a strange burrowing nocturnal insectivore is perhaps most toxic among the mammals–with one glaring exception. At the beginning of the month we wrote about the clever echidna–a monotreme with unusual brain physiology.  The echidna’s closest relative, and the world’s only other remaining monotreme, the duck-billed platypus is the planet’s most poisonous mammal by far.  Not only do platypuses have bills, lay eggs, and utilize electrical sensory apparatus to hunt, but the male has a moveable poisonous spur on his hind legs which is attached to a venom-producing crural gland.  Only the male platypus is capable of producing a toxic peptide cocktail and injecting it through his spurs. Female platypuses (and all echidnas) have rudimentary spurs which drop off and lack functioning crural glands. Platypus venom causes pain and hyperalgesia—which means an increased sensitivity to pain–so you shouldn’t cuddle male platypuses no matter how adorable their funny little bills may look to you.

The crural glands...and the spur!

The Stanford neuroblog (from whom I borrowed the attached image of a platypuses’ poisonous organs and appendages), notes the similarity of platypus venoms with reptile venoms, “One evolutionary curiosity: the defensin-like peptides found within the platypus venom are also found within reptile venom. However, genetic analysis in 2008 revealed that the platypus peptides evolved independently from the reptile peptides, although both were derived from the same gene family.”  Its curious to think of how our ties with reptile forbears are manifested in the curious and endearing (and poisonous!) platypus.

Eek! Get down...he's got a platypus!

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