Review: Dietrich Mebs: Life with poison - How animals and plants cope with it and what we can learn from it
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 only exists through their toxins. Animals also catch prey with poisons. The toxic substances in animals, plants and fungi exceed everything that humans artificially produce in toxins and also everything that we can imagine.
Immunity to such animal and vegetable poisons provides survival benefits and is often even vital: snakes are immune to their own poisons. Hedgehogs and mongooses have a certain resistance to snake venom, which is why they can fill the stomach with adder like cobras.
What is a poison
Dietrich Mebs shows the contradicting meaning of the term poison. The English "gift" still refers to a gift, as was the case in Middle High German and echoes in the German "dowry". The German "dose" comes from the Latin-Greek word for "gift, gift" and implies that a large amount of a substance can become toxic. Paracelsus defined in the 16th century that "the dose alone makes a thing not a poison."
This is how Mebs, a shipwrecked man, dies of cardiovascular failure when he drinks sea water with the essential table salt. Conversely, the highly toxic digitoxin from the thimble is often the last resort for heart patients.
A toxin is a natural substance, and most animal and plant toxins consist of mixtures of different toxins. Toad poisons contain biogenic amines, steroids and alkaloids; Snake venom 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 use a tool such as a tooth (venomous snake) or a sting (scorpion) to bring this into another organism. As a result, it unfolds its effect in the foreign body.
Passive poison animals also produce their poison in glands or take it in with food (poison dart frogs), but cannot inject it into a foreign body. It gets into the other body through the digestive tract, for example when an animal bites the toad.
The term poisonous plant refers to the effect that substances in a plant have on people. According to Mebs, the cause of such poisoning is the compounds that plants produce as secondary metabolites.
What are poisons made of?
In the following, Mebs marks what poisons consist of. Two groups can be distinguished in the hardly manageable diversity.
On the one hand there are small molecular 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 created as a product of photosynthesis. Immeasurably many peptides and proteins are formed from 20 amino acids.
Both types of poisons are overwhelmingly diverse in animals, and only a fraction of them are known to date.
Clownfish have been superstars since the movie “Finding Nemo”. They live in symbiosis with sea anemones in coral reefs and are therefore also called anemone fish. Usually the anemones poison small fish that get between their tentacles with their nettles and then consume them. However, the anemone fish not only hide in the tentacles of the anemones, the anemones use their weapons to keep the fish away from predators.
The fish eats parasites that damage the sea anemone, and its excrement contains the minerals sulfur and phosphorus that are important for the anemone. On the one hand, sea anemones cover themselves with a mucous membrane that contains proteins that perforate cell membranes, and, on the other hand, they inject toxins into their tentacles with nettle cells.
In experiments conducted by Mebs, Prussian fish of the same size as the clownfish died at less than 0.5 mg of the toxin in 15 minutes. Clownfish, however, survived even high concentrations of the poison. However, the different species of anemonefish are very sensitive to toxins that do not come from “their” sea anemone.
In addition, the fish produce a thin layer of mucus, which protects them even in the closest contact with the nettles. The clown fish thus prevent the anemone from unloading their nettles and pretend that they are part of the anemone itself. Certain cancers can also live in sea anemones. Instead of a slime, it protects a chitin layer.
Prussian fish or small whiting, which benefit from the prey of fire jellyfish and Portuguese galleys, have no protective layer of mucus that defuses the nettles. You can only rely on your swimming skills. If they come into contact with the tentacles, they will be nettled and eaten - a form of natural selection.
The ant frog
The red wryneck frog of West Africa lives undisturbed between poisonous “stink ants”, which kill frogs with their poison and then eat them. In addition, the ants are extremely aggressive. However, the frog with black flanks and a red back can be found in the middle of the ants' structures, which protect it effectively from enemies.
His skin secretion contains two peptides with chains of 9 and 11 amino acids. Mebs synthesized and wetted these peptides, which are the main prey of the stink ants. The termites treated in this way touched the ants with their antennae and then left them alone, while they immediately killed and ate termites without this "coating". Mebs describes the secretion of the wryneck frog as a “chemical camouflage helmet”.
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. Rather, predators who disguise themselves as members of their prey are widespread in nature. For example, the skull swarmers camouflage themselves with fatty acids such as palmitic, stearic or oleic acid, which are similar to those of the bees whose sticks they penetrate. While the bees think he is their own kind, he uses their honey.
Wasps take on the smell of fire ants, lay their eggs in their burrows, and the wasp larvae eat the ant brood.
Scientists are just beginning to research what Mebs calls natural appeasement. It's not just about camouflaging and deceiving, it's also about reducing the aggressiveness of other species.
It is not a symbiosis from which several species benefit or parasitism, where the parasite damages another species, but a probiosis. Several species live side by side without harming themselves, but also without special advantages.
Ants have a poison gland that covers most of the abdomen and is filled with 50% formic acid. They spray them in the direction of an attacker and at the same time warn 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.
Ground beetles also spray formic acid from their anal glands - even with a concentration of up to 75%. Chitin also protects the glands in them.
Scourge scorpions spray poison from their tail thread, which consists of 84 percent acetic acid, 5 percent caprylic acid and 11 percent water.
The ant-lion, the larva of the ant-juvenile, lurks at the bottom of a sand funnel for ants and other insects. With his jaw pliers, he injects a deadly poison. It releases ants as soon as they release their poison. However, since ants bite and then spray their acid, the larva takes care that the ant does not bite. It neatly eats the soft abdomen of its victims, but leaves the poison bladder intact.
The South American poison dart frogs feed on ants, are themselves resistant to the acid and store the poison of their prey to a large extent in the skin, which makes them dangerous passive poisonous animals themselves.
Toad lizards, which eat ants, envelop them in the throat with a slime secretion, which prevents the ants from using their poison.
Under the heading "Drone Battle", Mebs discusses how the female bees, the drones, are thrown out of the hive 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 spikes.
Peptides and enzymes in bee venom are among nature's strongest allergens, according to Mebs. Even in humans, a single sting may produce anaphylactic shock.
The bee protects itself with a layer of chitin around the poison 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. As the killing of the threats shows, the bees themselves are not resistant to their poison. The queen, according to Mebs, kills rivals with a stab.
The colorful birds called bee-eaters remove the sting and poison of the bees by rubbing the animals on branches.
Bombardier beetles perfect chemical defense. First it pops out of her abdomen, then it sprays a hot and smelly liquid. It is hydroquinone and hydrogen peroxide in a concentration of 25%, which the beetle stores in a bladder.
This mixture would be highly explosive if it did not also contain an inhibitor that prevents both chemicals from reacting. The beetle presses the mixture into a second chamber, where oxygen is released by catalysis from hydrogen peroxide and hydroquinone is oxidized to benzoquinone. The released heat almost brings the mixture to a boil, according to Mebs. The oxygen forms the propellant.
Animals have to defuse plant poisons to be able to eat these plants. Cabbage, horseradish, mustard and rapeseed protect themselves with mustard oil, which they release as soon as plant tissue is injured. According to Mebs, like the bombardier beetle, it is a two-component system that is only triggered when the situation requires it - comparable to a grenade that explodes on impact.
The cabbage white caterpillars defuse this "bomb" by preventing the mustard oil from releasing its intestine with the nitrile-storing protein. Instead, the mustard oil glycosides produce non-toxic nitrile compounds.
The locust, on the other hand, forms a sulfatase enzyme in its intestine, which also defuses the "mustard oil bomb".
Predator and prey
Poison and antidote arm themselves in evolution. The rough-skinned newt from the western United States has highly toxic tetrodotoxin compounds. Garter snakes chase him anyway: their sodium channels do not respond to the poison as would be the case with other living things.
The Asian tiger snake stores the poison of toads, against which it is immune, in the skin glands on the neck.
Brazilians love Mussurana, a two-meter long snake that eats other snakes, including the highly poisonous Jararaca. It wraps itself around its prey. It is immune to the poison. Then she unhooks her jaw and pushes it alternately over the body of the venomous snake, sending her victim into the stomach with peristatic movements.
Venomous snakes are usually immune to their own poison, but not to other snakes.
The liver and the saucepan
According to Mebs, we poison ourselves with harmful smoke and fumes because we safely release chemicals in the environment against which we have no innate protection. However, we also have our liver, whose enzymes induce toxic substances.
We learned to grow our crops in such a way that they no longer contain any substances that are toxic to us. In addition, cultural techniques help us to neutralize plant toxins. Whether we remove the skin, cook, fry or grill our food, all parts of the cassava contain raw, highly toxic hydrocyanic acid glycosides. However, the hydrocyanic acid is removed by peeling, grating, cooking, pressing, roasting and drying.
In the case of cucumbers, zucchinis, chicory, asparagus and pumpkins, the toxic bitter substances were cultivated. However, poisoning from the glycoside cucurbitacin occurs again and again, and this bitter substance is not removed by roasting and cooking. Mebs therefore advises hobby gardeners to stay away from these vegetables if they taste bitter.
The biologist and biochemist Prof. Dr. Friedrich Mebs works in forensic medicine as a proven expert in toxicology and trace analysis. Although he examines highly complex biochemical compounds in organisms (more precisely the microscope) in “Life with Poison” that produce what we call poisons, the many examples from the flora and fauna are not only understandable for laypeople, but also for laypeople also described exciting.
Where the superficial look only sees beautiful butterflies or buzzing bees, Mebs introduces you to a world full of biological-chemical warfare agents, animal grenade launchers and techniques of camouflage, deception, protection and attack, which we would have to call refined if there is a conscious plan behind it would be stuck.
The mechanisms by which animals not only produce poisons but also protect themselves against them are ideally suited to transfer them to cultural techniques.
All in all, a book worth reading (published in 2016 by S. Hirzel Verlag Stuttgart) that opens the view to an unimagined diversity of nature. (Dr. Utz Anhalt)
Author and source information
This text corresponds to the specifications of the medical literature, medical guidelines and current studies and has been checked by medical doctors.
Dipl. Social Science Nina Reese
- Dietrich Mebs: Life with poison: How animals and plants can cope with it and what we can learn from it, Hirzel, S., Verlag; Edition: 1st edition 2016