The words toxic and poisonous are often used interchangeably in popular language. Many of us think that they are synonyms, usually used to refer to the fact that an animal, plant or fungus has a chemical compound that is harmful.
Although this definition is the closest to the popular one, the truth is that spinning a little more finely we can find differences between toxic and poisonous being very important for the world of biology.
Next we are going to see what the differences are between these two words, relating it especially to the animal world.
Differences between toxic and poisonous: learning to distinguish between both concepts
In nature, there are countless animals that synthesize their own chemical compounds as a method of defense against predator attacks or, also, as a strategy to prey on other animals.
The synthesis and use of these substances is a very effective but also expensive strategy: Nothing in the animal world is free and producing toxins is even less so especially if we take into account that the foods that provide them with substances and energy to produce them are not always obtained.
Many evolutionary biologists believe that the ability of certain species to produce toxins is attributable to the randomness of the genome. As surprising as it may seem, it is believed that throughout the history of evolution it has happened that an individual of a species, by mere chance, has suffered some type of mutation in its genetic code that has meant that instead of synthesizing a protein normally does so with an alteration.
It may happen that after the mutation, the new substance is toxic to other animals, which means that the individual that presents it is protected or has a certain advantage within its species and its environment. If before it was an easy prey, now it is an indigestible prey for its predator and, if what happened was that before it had to hunt to feed itself, now it has an element that allows it to kill its victims more quickly.
Synthesizing a toxicant is an advantageous trait that makes individuals who have the mutation more likely to survive and reproduce This will progressively cause the ability to produce the toxic to become a generalized ability in that species thanks to natural selection, fixing the trait in the species although this does not mean that the species is toxic and/or poisonous. These two words applied to living beings have their differences, which we will see later.
How is a poison different from a poison?
To understand the differences between what is toxic and what is poisonous, it is necessary to make a brief comment on what these two words mean in general terms. In Spanish, we use the terms “toxic” and “poisonous” as if they were synonyms and, generally, when we use them to describe the organism we want to indicate that that animal, plant, fungus or other has a chemical component that can be harmful to other beings. alive.
Instead, other languages do make a distinction between both concepts, being the case of the English language. In that language there are the words “venomous” (“toxic”) and “poisonous” (“poisonous”), which are used differently depending on the characteristics of the animal when making use of its toxins. We will look at these differences in more detail below.
1. The toxin is the unit, the poison the combination
The toxin would be the unit, while the poison would be the combination of several of them. A toxin is that harmful substance produced by an organism, which can cause damage to another living being.
Here we can understand the first difference between a toxin and a poison: the venom is composed of one or more toxins, while the toxin itself is simply a functional unit which can give rise to different types of poisons.
Normally, toxins are peptides composed of several amino acids that are joined together by peptide bonds and give rise to a protein. When a toxin is made up of a long chain of complex amino acids, we say that we are dealing with a toxic protein
An example of a toxic protein would be ricin, produced by the species Ricinus communis which contains two chains with more than 260 amino acids each. That is, it would be a poison composed of a single toxin.
Another different case would be scorpion venom Androctonus bicolor, liquid which presents up to 103 unique toxic peptides. This means that the venom of this arachnid is composed of more than 100 toxins.
2. Venom attacks, toxin is passive
Poisonous animals inject poison, while toxic animals simply contain toxins but do not have to use them voluntarily We can say that the poison is used as a weapon, it “attacks”, while the toxin is simply found in the animal’s body, in a more or less passive way.
For an animal to be considered poisonous, it should have some element in its anatomy that allows it to inject toxic compounds into the bloodstream of its victim, whether jaws, fangs, spurs or stingers…
3. Toxic animals do not inject toxins
Related to the previous point, we can say that Those animals described as toxic do not have limbs that can be used to inject a poisonous substance Many amphibians produce toxins, but they have nothing to attack or make voluntary use of, so they cannot be considered poisonous.
An example of a particularly toxic amphibian is the case of dendrobate frogs (Dendrobatidae), which have neither stingers nor fangs nor any system to inoculate their powerful toxins. Instead, they secrete their toxic compounds through the skin naturally, causing discomfort and serious symptoms to anyone who dares to lick them.
4. Toxic animals warn, poisonous ones go unnoticed
Toxic animals warn all potential predators that they are not going to like what they are going to find while poisonous animals usually do just the opposite, hiding and going unnoticed.
This is because many toxic animals are rarely predators, being animals that do not have great strength, size, or defensive limbs. Since they could do little when faced with a predator’s bite, their body has adapted to warn them not to dare because, if they do, they run the risk of becoming poisoned.
The best way to warn is through visual signals, the most striking being the use of bright colors such as blues, yellows, greens and phosphorous whites on a black background, as is the case of many dendrobates frogs. This is also observed in some plants and fungi, and this phenomenon is called aposematism.
Instead, Venomous animals are usually predators that use their toxins to weaken their victim while hunting, making the predation process quick and less energetically costly. Therefore, it is not worth it to attract the attention of their victim and many poisonous species have colors that allow them to camouflage themselves with the environment.
An example of this is poisonous snakes. It doesn’t matter if we are in the desert, in the countryside, in the jungle or in the savannah. Whatever the environment, we will find this type of reptiles whose coloring will make them camouflage very well so that their victims do not see them, even when they are being attacked with their poison.
5. Neither toxic nor poisonous: toxungen
Apparently, Not all animals that produce toxins are toxic or poisonous There are animals that produce toxins and contain them in their organism; they cannot inject them but they can make defensive and voluntary use of them: toxungenous organisms.
In this category we would find animals that produce toxins but do not inject them through jaws, fangs or stingers, but they do not wait to be ingested or touched before releasing them.
An example of a toxungogenic animal would be skunks (Mephitidae) These animals are known to expel a foul-smelling chemical from their anal glands when they feel threatened. This substance is harmless to humans, but very harmful to domestic animals such as dogs and cats, which, after smelling it, may suffer vomiting, dizziness, temporary loss of vision and other serious symptoms.
