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Living with poison - meaning for animals, plants and humans
Animals and plants compete to produce effective poisons. Evolution is not harmonious, but organisms protect themselves from being eaten. Poisons are extremely effective. The biodiversity of plants exists only through their poisons. But animals also go poachers with prey. The toxins in animals, plants and fungi surpass everything that humans artificially produce from toxins and everything we can imagine.
Immunity to such animal and plant poisons provides survival benefits and is often even vital: snakes are immune to their own poisons. Hedgehogs and mongooses have some resistance to snake poisons, and that's why they can fill their stomachs with cootheads like cobras.
contents
- What is a poison?
- What are poisonous animals and plants?
- What are poisons made of?
- clownfish
- The ant frog
- Wolves in sheep's clothing and peaceful coexistence
- formic acid
- Men murder
- Bombardier beetle
- Disarm poisons
- Robber and prey
- snake eater
- The liver and the cooking pot
- summary
What is a poison?
Dietrich Mebs shows the contradictory meaning of the term poison. The English "gift" still refers to a gift, as was the case in Middle High German and the German "dowry" lingers. The German "dose" comes from the Latin Greek word for "gift, gift" and implies that a larger amount of a substance can become toxic. Paracelsus defined in the 16th century that "the dose alone makes a thing not a poison."
Animal and plant toxins usually consist of a mixture of different toxins. Snake venoms contain, for example, toxic peptides and proteins. (Image: dvrcan / fotolia.com) So dies, explains Mebs, a shipwrecked from cardiovascular failure, when he drinks seawater with the vital salt. Conversely, the highly toxic digitoxin from the thimble is often the last resort for patients with heart disease.
A toxin refers to a natural substance, and most animal and plant toxins consist of mixtures of different toxins. Toad venoms contain biogenic amines, steroids and alkaloids; Snake venoms toxic peptides and proteins.
What are poisonous animals and plants?
According to Mebs, there are active and passive poison animals. Active poisonous animals produce a poison in a gland and bring it with a tool such as a tooth (poisonous snakes) or a sting (scorpions) into another organism. As a result, it unfolds its effect in the foreign body.
Passive poison animals also produce their poison in glands or ingest it with food (poison dart frogs), but can not inject it into a foreign body. In the other body it passes through the digestive tract, for example, when an animal bites the toad.
The term poisonous plant refers to the effect of substances in a plant on humans. The cause of such intoxications, according to Mebs, are the compounds that plants produce as secondary metabolites.
What are poisons made of?
In the following Mebs indicates what poisons consist of. In the hardly manageable diversity, two groups can be distinguished.
On the one hand there are small molecule toxic compounds such as formic, acetic or hydrocyanic acid, alkaloids such as nicotine and caffeine, steroid glycosides such as digitoxin or bufadienolide (toad poison).
On the other hand, large molecules such as peptides and proteins are the product of photosynthesis. Out of 20 amino acids, immeasurably many peptides and proteins are formed.
Both types of poisons are found in overwhelming diversity in animals, and only a fraction of them are known to science.
clownfish
Clown fish have been superstars since the movie "Finding Nemo". They live in symbiosis with sea anemones in coral reefs and are therefore also called anemonefish. Normally, the anemones poison small fish that fall between their tentacles with their nettles and then consume them. But the anemone fish are not only hiding in the tentacles of the anemones, but the anemones keep the fish with their weapons predators from the body.
The fish eats parasites that damage the sea anemone, its excrements contain the important for the anemone minerals sulfur and phosphorus. Sea anemones cover themselves with a mucous membrane containing proteins that perforate cell membranes, and secondly, they inject toxins with nettle cells in their tentacles.
Clown fish live in symbiosis with sea anemones, for example by protecting each other from predators. (Image: kamera_d / fotolia.com) In experiments conducted by Mebs, Prussian fish of the same size as anemone fish died at a dose of less than 0.5 mg of the toxin in 15 minutes. Anemone fish, on the other hand, survived even high concentrations of the poison. However, the different species of anemone fish are very sensitive to toxins that are not from "their" sea anemone.
In addition, the fish produce a thin layer of mucus, which protects them even with the closest contact with the nettles. The clown fish prevent the anemones from unloading their nettles and pretend they are part of the anemone itself. Certain cancers can also live in sea anemones. Instead of a mucus she protects a chitin layer.
Preußenfische or small whiting, which profit from the prey of fire jellyfish and Portuguese galleys, have no protective mucus layer, which defuses the nettles. They can rely solely on their swimming skills. When they come into contact with the tentacles, they are tied and eaten - a form of natural selection.
The ant frog
The red wryneck frog of West Africa lives unmolested between poisonous "stinking ants" who kill frogs with their poison and eat them afterwards. In addition, the ants are extremely aggressive. The frog with black flanks and red back, however, can be found in the midst of the ants' buildings, which effectively protect it from enemies.
In his skin secretions are two peptides with chains of 9 and 11 amino acids. Mebs synthesized these peptides and wetted termites with them, which are the main booty of the Stink ants. The treated termites felt the ants with their antennae and then left them alone, killing and eating termites without this "paint". Mebs called the secretion of the wryneck frog as a "chemical Tarnhelm".
Wolves in sheep's clothing and peaceful coexistence
The wolf in sheep's clothing is not just a metaphor for people who deceive other people. On the contrary, predators that camouflage themselves as conspecifics of their prey are widespread in nature. Thus, the skullcutter disguises itself with fatty acids, such as palmitic, stearic or oleic acid, which are similar to those of bees, in whose sticks it penetrates. While the bees consider him their equals, he uses their honey.
Wasps take on the smell of fire ants, lay their eggs in their burrow, and the wasp larvae eat the ant brood.
Scientists are just beginning to explore what Mebs calls natural appeasement. It is not just about camouflage and deceit, but also about reducing the aggressiveness of other species.
It is not a symbiosis that benefits several species, or parasitism, where the parasite damages another species, but probiosis. Several species live next to each other without harm, but without having any special advantages.
formic acid
Ants have a venom gland that covers most of the abdomen and is filled with 50% formic acid. These spray them in the direction of an attacker and warn at the same time other ants. They themselves have a chitin membrane that does not let the acid through. They produce the acid from the amino acids serine and glycine.
Forest ants spray formic acid on their attackers when they feel threatened. (Image: Rainer Fuhrmann / fotolia.com) Ground beetles also spray formic acid from their aftergrowths - even at a concentration of up to 75%. Also with them chitin protects the gland ducts.
Scourge scorpions spray poison from their tail thread, consisting of 84 percent acetic acid, 5 percent caprylic acid, and 11 percent water.
The antlion, the ant damm larva, lurks at the bottom of a sand funnel for ants and other insects. He uses his jaws to inject a deadly poison. He immediately releases ants when they release their poison. However, as ants first bite and then spray their acid, the larva takes care that the ant does not even bite. He neatly eats the soft abdomen of his victims, but leaves the venom bladder intact.
The South American poison dart frogs feed on ants, are themselves resistant to acidity and store the venom of their prey to a high degree in the skin, which makes them even dangerous passive poisonous animals.
Toad-eagles, which eat ants, envelop them in the throat with a mucous secretion, which prevents the harvest ants from using their poison.
Men murder
Under the heading "Drone Battle", Mebs discusses how the female bees, the drones, are thrown from the stick by the workers after they have fulfilled their biological task of fertilizing the queen. The female bees also kill the defenseless drones with their poison sting.
Peptides and enzymes in bee venom are among the strongest allergens in nature, according to Mebs. Even in humans, a single sting may cause anaphylactic shock.
The bee itself protects itself with a chitin layer around venom gland and poison reservoir. "A funnel-shaped valve at the exit of each glandular cell also prevents poison from flowing back out of the reservoir and destroying the cell," writes Mebs. The bees themselves are not resistant to their poison, as the killings show. The queen kills, according to Mebs, competitors with a stitch.
The colorful birds named Bee-eaters remove the sting and poison of the bees by rubbing the animals against branches.
Bombardier beetle
Bombardier beetles perfect the chemical defense. First, it pops out of her abdomen, then spray a hot and stinking liquid. These are hydroquinone and hydrogen peroxide at a concentration of 25%, which the beetle stores in a collecting blister.
This mixture would be highly explosive if it did not additionally contain an inhibitor that prevents reaction of both chemicals. The beetle pushes the mixture into a second chamber, where oxygen is liberated by catalysis from hydrogen peroxide and oxidizes hydroquinone to benzoquinone. The released heat brings the mixture to a boil, so Mebs. The oxygen forms the propellant.
Disarm poisons
Animals have to defuse their pesticides in order to eat these plants. Cabbage, horseradish, mustard and rape are protected with mustard oil, which they release when plant tissue is damaged. It is, as Mebs, like the bombardier beetle, a two-component system that is triggered only when the situation requires it - comparable to a shell that explodes on impact.
Horseradish and other plants repel pests with mustard oils. (Image: photocrew / fotolia.com) The caterpillars of the cabbage whitewash defuse this "bomb" by their gut with the nitrile-storing protein prevents the mustard oil releases. Instead, the mustard oil glycosides give rise to non-toxic nitrile compounds.
In contrast, the locust forms a sulfatase enzyme in its intestine, which also defuses the "mustard oil bomb".
Robber and prey
Poison and antidote rearm in evolution. Thus, the rough-skinned newt from the west of the USA has highly toxic tetrodotoxin compounds. Garter snakes chase him anyway: their sodium channels do not respond to the poison as it would be the case with other creatures.
The Asian tiger water nutter stores the poison of consumed toads, against which it is immune itself, in skin glands on the neck.
snake eater
The Brazilians love the Mussurana, a two-meter-long snake that eats other snakes, including the highly venomous Jararaca. She wraps herself around her prey. She is immune to the poison. Then she unhooks her jaws and pushes them alternately over the body of the venomous snake, carrying her victim with peristatic movements in the stomach.
Venomous snakes are usually immune to their own poison, but not to other snakes.
The liver and the cooking pot
According to Mebs, we poison ourselves with harmful smoke and fumes because we are free to release chemicals in the environment that we do not have innate protection for. However, we also have our liver, whose enzymes induce toxic substances.
We learned to breed our crops so that they no longer contain substances toxic to us. In addition, cultural techniques help to neutralize plant toxins. Whether we remove the shell, cook our food, fry or grill - so included in the raw state, all parts of the manioc highly toxic cyanogenic glycosides. However, by peeling, grating, cooking, pressing, roasting and drying, the hydrogen cyanide is removed.
The root vegetable cassava is poisonous in the raw state, since it contains hydrogen cyanide. During processing, however, the toxin is destroyed. (Image: patarapong / fotolia.com) For cucumbers, zucchinis, chicory, asparagus and pumpkins, the poisonous bitter substances were grown out in cultivation. However, poisoning by the glycoside cucurbitacin occurs again and again, and this bitter substance is not removed by frying and cooking. Mebs advises amateur gardeners to keep their hands off these vegetables if they taste bitter.
summary
The biologist and biochemist Prof. dr. Friedrich Mebs works in legal medicine as a proven expert in toxicology and trace analysis. Although in "Living with Poison" he examines highly complex biochemical compounds in organisms (more precisely, the microscope) that produce what we call poisons, the many examples from the plant and animal world are not only understandable to laymen, but also also described exciting.
Where the superficial view sees only beautiful butterflies or buzzing bees, Mebs introduces us to a world of bio-chemical warfare agents, animal grenade launchers, and techniques of disguise, deception, protection and attack, which we would have to call clever if there is a conscious plan behind it would be stuck.
The mechanisms by which animals not only produce but also protect against poisons are well suited to apply them to cultural techniques.
All in all a very readable book (published in 2016 by S. Hirzel Verlag Stuttgart), which opens the view to an unexpected diversity of nature. (Dr. Utz Anhalt)