A toxic living being is one that synthesizes a substance that can harm humans, while a poisonous one inoculates these toxins through structures in the bloodstream.
Many living beings synthesize chemical compounds that serve as a method of defense against attacks by predatorsor, failing that, to prey on other animals. This evolutionary strategy is extremely effective, but also very expensive: producing toxins does not come for free, less in an environment where energy and food are conspicuous by their absence.
Interestingly, several investigations postulate that the production of toxins could be due to the randomness of the genome of the species, or what is the same, to the random appearance of mutations that code for these biological events. For example, it may be that a vital ancestor of a series of taxa suffered a point mutation in which, instead of synthesizing a normal protein in a metabolic pathway, it gave rise to a toxin.
If this mutation helped the living being to function better in the environment and stand up to predators more efficiently, that trait, theoretically, could become fixed in the population. If a novel (and heritable) trait at the evolutionary level is advantageous, it would allow its carrier to reproduce more easily, which would make that trait increasingly present in the following generations.
Thus, the mechanisms of toxin production could be the product of randomness, but their fixation in different species responds to natural selection, that omnipotent force that conditions the evolution of living beings in the long term. Based on these interesting premises, we present the 5 differences between toxic and poisonous.
- We recommend you read: “The 12 most poisonous animals on the planet”
How is a poison different from a poison?
It is curious to know that, in Spanish, we usually use the terms “toxic” and “poisonous” interchangeably, when referring to a living being that can be harmful due to the chemical compounds it synthesizes. Anyway, if we cross the ocean or move to Great Britain we will see that in English a clear distinction is made: venomous and poisonous are not the same.
It is difficult to explain the difference between both terms without having an extensive biological background and, therefore, we expose the 5 differences between toxic and poisonous laying a series of chemical bases along the way. Don’t miss it.
1. The toxin is the unit; The poison, the union
In the first place, we must know what is the functional unit that concerns us here. A toxin is a poisonous substance produced by an animal or plant that causes harm to other living things. The main difference between the terms “toxin” and “poison” is very simple: a poison is composed of one or more toxins, while the toxin is the functional unit that gives rise to the different types of poison.
Usually, toxins are peptides composed of several amino acids, the basic molecules that, linked by peptide bonds, give rise to a protein. When the toxin is formed by a long chain of complex amino acids, we say that we are facing a toxic protein. This is the case of ricin, produced by the Ricinus communis tree. Specifically, it contains two chains with more than 260 amino acids each.
On the other hand, extremely lethal species such as the scorpion Androctonus bicolor have up to 103 toxic peptides unique when it comes to producing their venom. This means that the poison produced by this animal is composed of more than 100 toxins: the toxin is the unit, and the poison, the union of toxins.
2. The toxin is not injected, but the poison is
However, as we have said before, a poison can be composed of a single toxin. So what really differentiates the two compounds? Actually, the key distinction between toxic and poisonous is this: the toxic is present inside the body, while the poisonous is injected.
In other words, toxins are poisons (or units) produced by organisms in nature, and poisons are toxins injected by a bite or sting. Thus, for an animal to be considered poisonous, it must have jaws, fangs, stingers, spurs or some structure that crosses the skin and allows the entry of toxic compounds into the bloodstream of its predator.
3. Toxic animals do not have injection structures
This difference goes hand in hand with the previous one, because based on what has been described, an extremely toxic frog cannot be considered poisonous. It does not have the means to inoculate toxins and, therefore, its defense mechanisms only become effective when a predator tries to eat it.
Within the group of toxic but non-poisonous animals, dendrobates frogs (Dendrobatidae) are the most often cited. These precious amphibians secrete toxins on the surface of the skin capable of ending the life of many living beings, but since they cannot inoculate these compounds directly on a prey, they are not considered poisonous.
Especially striking is the most dangerous frog in the world par excellence: Phyllobates terribilis. Experimental media have estimated that the skin of P. terribilis contains enough toxins to kill 22,000 mice with simple surface contact. The dose of batrachotoxins (the toxins of these species) that can kill a human being is unknown, but it is estimated thata single frog could kill 10 people.
4. Toxic animals warn, but poisonous animals do not
If we look at the color of dendrobate frogs, we will see that they have garish tones (blue, phosphorite yellow, white, green) contrasted with extremely striking black patterns. This phenomenon is known as aposematism, where theanimal warns the predator through visual stimuli that it will surely die if ingested.
On the other hand, the black mamba (Dendroaspis polylepis), one of the most venomous snakes in the world, has a blackish dorsal coloration and a cream-colored belly, something not at all striking. Venomous animals such as scorpions, spiders, tarantulas and snakes do not always display alert tones, because their interest is that living beings confuse them with the environment in order to prey on them more easily.
In other words, a toxic animal does not seek to interact with the environment and warns with its coloration of it, while a poisonous predator usually camouflages itself in the shadows to be able to kill its prey faster. In many cases, going unnoticed is one of the best qualities a killer can have.
5. Not all toxin-producing animals are toxic or poisonous
Perhaps this last statement has surprised you, because so far, we have not separated ourselves from two different but very similar concepts: the toxic and the poisonous. However, scientists and biologists have proposed athird category: “toxugenous” animals (Toxungenous animals is the correct term, but it does not have a Spanish translation).
This last group of living beings do not inject their toxins through jaws, fangs or stingers, but neither do they wait to be ingested or touched to release them. For example, bombardier beetles excrete when they feel threatened a liquid rich in benzoquinones, which repel predators and irritate their superficial mucous membranes. They can even secrete these fluids into their predator’s stomach, in order to be released alive before digestion begins.
Something similar happens with skunk (Mephitidae) and their famous foul-smelling chemical emissions. Although the encounter with this mammal may remain anecdotal in humans, the reality is that a dog or cat can suffer vomiting, dizziness, temporary vision loss and experience other unpleasant symptoms.
Summary
We have moved in quite complex terminological clusters, but the truth is that, on a practical level, the terms toxic and poisonous are very similar and can be used interchangeably. Although a dendrobate frog cannot inject its toxins, we all say that it is poisonous, because after all it produces toxins that could kill us.
The real interest of the differences between toxic and poisonous lies in describing the adaptive mechanisms of living beings in different environments and situations. By creating this terminological split, biologists are able to better understand why one animal injects the toxins it produces and another chooses to secrete them on the surface of its body.
To the classic question “what do you do?” I always answer “basically I am a psychologist”. In fact, my academic training has revolved around the psychology of development, education and community, a field of study influenced my volunteer activities, as well as my first work experiences in personal services.