Tuesday, 21 February 2012

Poisonous creatures

I got some of this information from an article in The New York Times and from other Internet sources which I think you will find most interesting.

Many insects, frogs, snakes, jellyfish and other similar creatures use venoms and repellents. Mammals generally rely on teeth, claws, muscles or quick wits. But the rare mammal has discovered the wonders of chemistry.

The African crested rat which is large, furred and helmeted is one such creature. It permeates its specialized pelt with potent toxins harvested from trees for the purpose of deterring predators with chemical weapons.

Skunk scent has the same sulfurous stink of a swamp. The male duckbilled platypus infuses its heel spurs with a cobra-like poison. The hedgehog sharpens the sting of its spines with venom chewed off the back of a cane toad whose venom is fatal to anyone or anything that gets it on their skin.

And there's more: capuchin monkeys ward off pests with extracts gathered from millipedes and ants, while black tailed deer rub themselves liberally with potent antimicrobial secretions produced by glands in their hooves.

William Wood, a chemistry professor at Humboldt State University in California, said these secretions are effective against an array of micro-organisms, including acne bacteria and athlete's foot fungus.

For each newly identified chemical fix, researchers seek to identify its benefits, drawbacks and evolution, and to compare it with other known cases of chemical arms. Distinctive themes have emerged.

For example, whereas poisonous insects tend to advertise their unpalatability with bright colors, most mammals and their mammalian predators, which are nocturnal or crepuscular, use strong contrast between dark and light.

This is why skunks and the African crested rat employ black against white. The pattern is visible in very low light, and its message is, “I'm noxious.”
In a paper on the African crested rat, Fritz Vollrath of Oxford University and his colleagues described its special traits.

The rat spends hours gnawing on the bark and roots of the Acokanthera tree, from which it extracts the same heart toxin that African hunters have traditionally used to kill elephants. The rat then slavers the poison onto specialized hairs along its flank.

Each outer shaft is stiff and full of holes, and inside are long, fluffy microfibers. The applied toxin seeps through the holes and is wicked up and stored by the fibers. One bite by a predator can kill the predator. Researchers as of yet haven’t learned why the rat is immune to the toxin, or how its fate came to be bound up with the Acokanthera tree.

The rat eats a lot of things that other animals won't. If it eats something disgusting, it tries to spit it out and then clean it off, using its skin as a napkin. It is for this reason that earlier a crested rat, gagging on a toxic tree, may incidentally have ended up being protected against predation. Through evolution, the creature now depends on tree toxin for protection. Should that tree go extinct, the rat would follow.

Skunks synthesize their own toxins. Through anal scent glands at the base of the tail, they generate their noxious spray. I remember working in a residential school in Saskatchewan back in the 1950s that was located in an area surrounded by fields and forests. There was at many times, the scent of skunks everywhere and often the skunks were some distance away from the school.

At the heart of skunk spray is a thiol, the hallmark of nasty places high in lethal hydrogen sulfide and low in oxygen that smell like mines and swamps. Our nose is able to detect thiols at extremely low levels. Skunks have come along and capitalized on this. To deter a predator chasing at an unknown distance, the skunk goes for the mist effect; if the harasser is within view, the skunk may choose a stream to the face. Incidentally, one way to remove the thiols from your skin is to rub tomato juice over it.

The monkey is another creature willing to withstand extremely irritating chemicals to rebuff bloodsucking parasites. Capuchin monkeys are notoriously generalist and destructive in their sampling. You have to watch out or they'll drop branches on your head. They tear up chili peppers to release the capsaicin, rip apart millipedes to procure a few droplets of searing benzoquinones, and they'll roll around on a nest of carpenter ants to soak up the ants' formidable formic acid.

Capuchin monkeys get very agitated when they're anointing themselves with the toxin but they're keeping off parasites, and they seem to have a high threshold for pain. Besides, anointing is a social affair. They get into such a frenzy that the social order breaks down; everyone is anointing with everyone else," she said. "It's like a big, wild party—a party you don’t want to attend.

There are at least 1200 species of venomous fish, and they include the Stonefish, Lionfish, Scorpion Fish, Stargazer, and Toad fish.

Scorpion fish are a family of mostly marine fish that includes many of the world's most venomous species. As the name suggests, scorpion fish have a type of sting in the form of sharp spines coated with venomous mucus. The family is a large one, with hundreds of members. They are widespread in tropical and temperate seas, but mostly found in the Indo-Pacific. It's a good thing fish wouldn't survive long if loose on a plane. A new study finds there are more venomous fish than venomous snakes. The 1,200 presumably venomous fish tallied in a new study is six times previous estimates. Fish with a biting bite outnumber all other venomous vertebrates combined.

Box jellyfish are known for the extremely potent venom produced by some species: Chironex fleckeri, Carukia barnesi and Malo kingi are among the most venomous creatures in the world. Stings from these and a few other species in the class are extremely painful and sometimes fatal to humans.

Although the notoriously dangerous species of box jellies are largely, or entirely, restricted to the tropical Indo-Pacific, various species of box jellies can be found widely in tropical and subtropical oceans, including the Atlantic and east Pacific, with species as far north as California, the Mediterranean and Japan and as far south as South Africa and Australia and New Zealand.

The world's most venomous insect is an ant called the harvester ant. Its bite is equivalent to 12 stings used to kill a 2 kg (4.4 lb) rat.

Insect venoms are comprised of amino acids, peptides and proteins. They may include alkaloids, terpenes, polysaccharides, biogenic amines (e.g., histamine), and organic acids (e.g., formic acid). Venoms also may contain allergenic proteins, which can trigger a potentially lethal immune response in sensitive individuals which is why some people die after being stung by bees or wasps.

Biting and stinging are separate actions in ants. Some ants bite and do not sting. Some bite and spray venom on the bitten area. Some bite and inject formic acid with a stinger. Harvester and fire ants bite and sting in a two-part process. The ants will grab hold of someone’s skin with their mandibles, and then pivot around, repeatedly stinging and injecting venom. The venom includes an alkaloid poison. Fire ant venom includes an alarm pheromone which chemically alerts other ants in the vicinity. Chemical signaling is why the ants all appear enmass to sting a victim at once.

Fire ants typically nest in sand or soil. These ants build rather large mounds and tend to feed on plant life and occasionally crickets and smaller insects. When bothered, however, the fire ant sting is a venomous prick that feels like it’s burning with fire, hence the name and swells up into a painful pustule. A few small stings can be quickly treated and cured, but when the ants swarm, which they a often do, that’s when the trouble starts. 150 people a day are killed by these ants after the ants have swarmed over them.

The Hemiptera Bug has a distinctive ‘sucking’ mouthpart that resembles tubes. Most, of them in fact, feed on plant sap in one form or another, but a few, such as the Kissing Bug, feed on blood of larger animals and unfortunate humans. The bug can transmit Chagas Disease, and it is described as follows:

The symptoms of Chagas’ disease vary over the course of the infection. In the early, acute stage symptoms are mild and are usually no more than local swelling at the site of infection. As the disease progresses, over as much as twenty years, the serious chronic symptoms appear, such as heart disease and malformation of the intestines. If untreated, the chronic disease is often fatal. Current drug treatments for this disease are generally unsatisfactory, with the available drugs being highly toxic and often ineffective, particularly in the chronic stage of the disease.

The Giant Japanese or Asian Hornet an achieve lengths of 3 inches full grown and has been known, in numbers of only 20 or 30, to decimate an entire hive of honeybees. The sting can be lethal not just by allergic reactions but also due to its many toxins. Here are four interesting things about its sting:

a: Its sting has a higher concentration of the pain-causing chemical called Acetylcholine than any other stinging insect.

b: An enzyme in its venom can dissolve human tissue.

c: Containing at least eight distinctly different chemicals, the venom itself produces one such that actually attracts others of its kind to the victim.

d: Like all other hornets, it can sting repeatedly.

Wasps including the yellow jackets and hornets within the class, wasps vary in that they are relatively social, generally terrestrial, and almost every sub-species has a specific parasite or pest that it preys upon exclusively. Though wasps do not necessarily seek out humans to sting (unless territories are being threatened), it is the oft-allergic sting that does the most damage. Many people go into anaphylactic shock and die because of a single wasp sting.

Truly the most prolific killer of all times is the Tse Tse fly which is a carrier of the deadly sleeping sickness, the TseTse fly feeds on the blood of vertebrates. These insects spread the disease, trypanosomiases in humans by biting their victims and passing their venom through their mouth parts. The death toll in Africa is between 250-300 thousand human victims per year.

Mosquitoes are a terrible irritant and, because they feed on blood, can drive a person mad just by being outside in the right conditions. Eggs get laid and grow in stagnant areas of water and millions can hatch from one spot. But, the worst aspect of the mosquito is that it’s a carrier for blood-borne diseases, specifically: Malaria. Still numbering in the hundreds of million cases per year, malaria is responsible for more deaths than every other insect combined.

Ticks carry Borrelia burgdorferi, the bacterium that causes Lyme disease. Ticks get infected when they feed on mice, squirrels, birds and other small animals that can carry the bacterium. Ticks then spread the bacterium to humans. Two types of ticks are responsible: the western blacklegged tick in British Columbia and the blacklegged tick, sometimes called the deer tick, in other parts of Canada.

Ticks vary in size and colour; blacklegged ticks are very small. Before feeding, adult females are approximately 3-5 mm in length and red and dark brown in colour. Ticks feed on blood by attaching to animals or people with their mouth parts. Females are a little larger than males and when they’re full of blood can be as big as a grape. Younger tick life stages are smaller and, when unfed, are lighter in colour. People and pets can pick up ticks by brushing against vegetation.

The symptoms of Lyme disease usually happen in three stages, although not all patients have every symptom. The first sign of infection is usually a circular rash called erythema migrans or EM. This rash occurs in about 70-80 percent of infected people. It begins at the site of the tick bite after a delay of three days to one month. Other common symptoms include:

• fatigue
• chills
• fever
• headache
• muscle and joint pain
• swollen lymph nodes.

If untreated, the second stage of the disease can last up to several months and include;

• central and peripheral nervous system disorders
• multiple skin rashes
• arthritis and arthritic symptoms
• heart palpitations
• extreme fatigue and general weakness

If the disease remains untreated, the third stage can last months to years with symptoms that can include recurring arthritis and neurological problems. Fatalities from Lyme disease are rare however some people have died from this disease.
Poisonous spiders may not be as big of a threat as many people believe. Antivenin against spider bite has become very effective and it is rare people actually die from a spider bite. In the United States however, an average of six or seven people die from venomous spider bites each year.

The brown recluse spider is a very venomous and dangerous spider to people, but it is definitely not an aggressive spider and it only bites when threatened. Brown recluse spiders are also known as Loxosceles reclusa. Their bite can be quite bad. In South America recluse spiders are also know as brown spiders. In the U.S., a brown spider can be many different species; poisonous and non-venomous.

Black widow spiders are notorious because of the extreme potency of their neurotoxic venom. The genus comprises thirty-two recognized species and its occurrence is attributed to human mediated movement. It is found worldwide including places like North America, Africa, the Middle East, Iberian Peninsula, Australia, New Zealand, North and South America, and Hawaii.

Tarantulas can be large enough to eat birds and a myth is that they even attack chickens from time to time. Children in some parts of South America keep tarantulas as pets. The South American tarantula is the world's largest spider and sometimes reaches more than 20 cm (as big as your hand) in length. Tarantulas in North America are significant smaller than tarantulas in South America. The tarantula has a bad reputation, but it is not really as bad as it looks. A bite from a tarantula can be painful, but it definitely won't kill you.

In 1969 when I was driving through Mexico to get to Belize, I wondered why I kept seeing large black spots on the roads at night. I stopped to see. They were tarantulas and the reason why they were on the roads at night was they liked the warms roads that the earlier hot sun had created. Needless to say, I jumped back into my car as fast as I could. I had the fear that if I ran over anyone them, their poison would be on my tires and I would get the poison in my system if I had to change a tire.

I am going to put an end to his article. My skin is already crawling with imaginary beasties.

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