Amphibians are extremely hardy creatures. In their 300 million years of existence, they have survived mass extinctions, ecological upheavals and persistent threats from predators – which include human demand for their psychedelic compound. In the process of evolution, many amphibians, such as toads, have developed strange but highly effective defense mechanisms against predators.
Some are brightly colored to warn other animals of their toxicity, a strategy known as de-marking. However, others, such as the Sonoran Desert Toad (which happens to be North America’s largest native toad species) could easily be passed off as harmless due to their more subdued coloration and inconspicuous appearance.
When threatened, many such toads in the Bufonidae family, including the Sonoran Desert Toad, secrete a potent cocktail of poisonous toxins. These secretions come from skin glands such as the parotid glands, located around the animal’s back or neck area. This is the primary defense mechanism for a frog that is otherwise physically unable to defend itself against raccoons, chunks, snakes, or birds of prey such as eagles.
How does Toad use these compounds in the real world?
The parotid glands of the Sonoran Desert Toad produce two toxins, among others, of interest: 5-MeO-DMT and Bufotenine (a toxic DMT analog).
Both of these compounds have strong hallucinogenic properties that can throw off predators, allowing the toad to escape, relatively unharmed. Bufotenin goes one step further. At high enough concentrations, it can lead to severe physiological reactions. These reactions can include respiratory arrest, cardiac dysfunction, and extreme changes in blood pressure, which can be fatal to the predator.
A landmark 1956 study in Herpetologica found that these toxins, combined with a defensive posture and the inflated size of the adults, could repel predators quite effectively.
Because ethical considerations in research were less stringent during this time, researchers were able to forcibly apply toad toxins directly into the mouth of a three-month-old dog. For the next 30 minutes, the dog was physically incapacitated (although he made a full recovery later):
- He was foaming at the mouth
- He had persistent convulsions
- He lost control of his bladder
- His coordination was ‘extremely poor’
To observe how the toxins would work in a real-world scenario, the researchers then placed a chipmunk and a Sonoran desert toad in a cage. The toad, under threat, took a defensive stance:
- It exposed the back and neck area (where the parotid glands are located)
- Inflate its size by drawing in air
- He whistled loudly as he slowly forced the air out of his lungs
This aggressive stance, combined with the taste and smell of the toxins, visibly deterred the gopher from continuing its attack.
When the researchers noticed that similar-sized, non-toxic toads were attacked and eaten by the toad while the Sonoran desert toads were ignored, they concluded that the toad had decided not to hunt these toxic toads.
However, it is important to remember that this is the story of a skunk. As a species, they seem to have learned how to prey on these toads safely.
Is the Sonoran Desert Toad ever vulnerable?
Historical references, such as a 1930 article in Copeiavividly illustrate the dangers of preying on these toads:
- A fox terrier, having bitten one of these toads, succumbed in a few minutes
- A German shepherd was left paralyzed after just touching his nose to the frog, though he eventually recovered
Such incidents highlight the toad’s formidable defenses and highlight the fine line predators must walk when encountering this amphibian. Interestingly, there is no evidence to suggest that any known predator has developed physiological resistance to amphibian toxins. This is not to say that the toad is not eaten, but that preying on these creatures would, in most cases, lead to great discomfort or even death.
The most effective solution to successful toad prey was reported in a 1966 article published in Herpetologica. A raccoon in the Sierra Bacadéhuachi mountain range in Sonora, Mexico was observed using a clever tactic to avoid the toad’s toxic secretions.
It hunted toads by turning them on their backs and attacking through the abdomen, removing the glands known for their venom. This behavior suggests that mammalian predators, including skunks, ringtails, coatis, bobcats, and gray foxes, may have similarly adapted their hunting techniques to bypass the Sonoran Desert Toad’s toxic defenses, showing a remarkable example of predatory innovation and facial adaptation. strong chemical defenses.
The saga of the Sonoran Desert Toad and its predators exemplifies the dynamics of evolutionary adaptation. With its powerful defensive toxins, the toad has created an almost perfect deterrent, however the inexorable course of natural selection enables some predators to find and exploit a critical weakness. This interplay ensures that the balance of survival never stagnates, as each evolutionary innovation causes a reverse move in the complex chess game of predator-prey relationships.