Venom
is any of a variety of toxins [1] used by certain types of animals. Generally, venom is injected by such means as a bite or a sting. [2]
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VENOM TICKETS
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Venomous vs. poisonous
There is a difference between organisms that are venomous and those that are
poisonous,
[3] two commonly confused terms applied to
plant and
animal life.
- Venomous
, as stated above, refers to animals that deliver (often, inject) venom into their prey when hunting or as a defense mechanism.
- Poisonous
, on the other hand, describes plants or animals that are harmful when consumed or touched. [4] A poison tends to be distributed over a large part of the body of the organism producing it, while venom is typically produced in organs specialized for the purpose. [5] One species of bird, the hooded pitohui, although not venomous, is poisonous, secreting a neurotoxin onto its skin and feathers.
The
slow loris, a primate, blurs the boundary between poisonous and venomous. From patches on the inside of its elbows it secretes a toxin, which it is believed to smear on its young to prevent them from being eaten; however, it will also lick these patches, giving it a venomous bite.
Diversity
Arthropods and other invertebrates
Among animals using venom are
spiders and
centipedes, which also inject venom through fangs;
scorpions and stinging
insects, which inject venom with a sting (which, in insects such as
bees and
wasps, is a modified egg-laying device – the
ovipositor). Many
caterpillars have defensive venom glands associated with specialized bristles on the body, known as
urticating hairs, and can be lethal to humans (e.g., that of the
Lonomia
moth).
Because they are tasked to defend their hives and food stores, bees synthesize and employ an acidic venom (
apitoxin) to cause pain in those that they sting, whereas wasps use a chemically different venom designed to paralyze prey, so it can be stored alive in the food chambers of their young. The use of venom is much more widespread than just these examples, of course. Other insects, such as
true bugs and many
ants, also produce venom.
There are many other venomous invertebrates, including
jellyfish and
cone snails. The
box jellyfish is widely considered one of the most dangerous creatures in the world.
Fish
Venom can also be found in some
fish, such as the cartilaginous fishes –
stingrays,
sharks, and
chimaeras – and the
teleost fishes including
monognathus eels,
catfishes,
stonefishes and
waspfishes,
scorpionfishes and
lionfishes,
gurnard perches,
rabbitfishes,
surgeonfishes,
scats,
stargazers,
weever.
Snakes and other reptiles
The animals most widely known to use venom are
snakes, some species of which inject venom into their prey through hollow
fangs.
Snake venom is produced by glands below the eye and delivered to the victim through tubular or channeled fangs. Snake venoms contain a variety of
peptide toxins (
Proteases), which
hydrolyze protein peptide bonds, and
nucleases, which hydrolize the
phosphodiester bonds of
DNA. Snakes use their venom principally for hunting, though the threat of being bitten serves also as a defense. Snake bites cause a variety of symptoms including pain, swelling, tissue damage, low blood pressure, convulsions, and hemorrhaging (varying by species of snake).
Doctors treat victims of a venomous bite with
antivenom, which is created by dosing an animal such as a
sheep,
horse,
goat, or
rabbit with a small amount of the targeted venom. The immune system of the subject animal responds to the dose, producing
antibodies to the venom's active molecule; the antibodies can then be harvested from the animal's blood and applied to treat envenomation in others. This treatment can be used effectively only a limited number of times for a given person, however, as that person will ultimately develop antibodies to neutralize the foreign animal antibodies injected into them (anti-antibody antibodies). Even if that person does not suffer a serious allergic reaction to the antivenom, his own immune system can destroy the antivenin before the antivenin can destroy the venom. Though most people never require even one treatment of antivenin in their lifetime, let alone several, people who work with snakes or other venomous animals may.
Aristolochia rugosa and
Aristolochia trilobata, or "
Dutchman's Pipe," are recorded in a list of plants used worldwide and in the West Indies, South and Central America against snakebites and scorpion stings.
Aristolochic acid inhibits inflammation induced by immune complexes, and nonimmunological agents (carrageenan or croton oil). Aristolochic acid inhibits the activity of snake venom phospholipase (PLA2) by forming a 1:1 complex with the enzyme. Since phospholipase enzymes play a significant part in the cascade leading to the inflammatory and pain response, their inhibition could lead to relief of problems from scorpion envenomation.
Venom is also found in a few reptiles besides snakes, such as the
gila monster,
Mexican beaded lizard and certain members of the genus
Varanus
, such as the
perentie and
Komodo dragon.
Mammals
Some mammals are also venomous, including
solenodons,
shrews, the
slow loris, and the male
platypus.
See also
- Envenomation
- Schmidt Sting Pain Index
- Big Four (Indian snakes)
References
- {{DorlandsDict|eight/000115553|venom}}
- venom - Definition from the Merriam-Webster Online Dictionary
- Are Spiders Poisonous?
- ''E.g.'', Kenneth G. Wilson, ''The Columbia Guide to Standard American English''. 1993.
- Zoltan Takacs, The Biology of Venomous Animals. Session 1. Columbia University, 2001.