Not everyone actually cares whether vertebrates or invertebrates alike are left in their reptiles cage, live, waiting for death. For whatever reason they have been able to remove themselves from any compassion towards the suffering of another being which often comes with statements such as “that is nature”. Or have they? Is the prey really suffering?
To be clear on the common argument of it being natural for a predator to eat its prey alive, that is generally the case. One could also say that humans are naturally prey as much as they are predators, however humans do not generally accept being in that situation and are known to eradicate any predator that tries or succeeds to consume them. Keeping an animal captive is not natural and nor is confining a prey animal in with its predator natural. Apart from that, the point of natural versus unnatural does not provide any scientific support to support or condone the practices. By looking into pain we can use quantifiable information to support or not support the practice of feeding live food from both vertebrates and invertebrates.
First to define pain. This articles use of the word pain is based on the World Health Organisations definition being “an unpleasant sensory or emotional experience associated with actual or potential tissue damage, or described in terms of such damage”.
The stimuli that is causing pain is sensed by neurons which are known as nociceptors. The registration of noxious stimulus and subsequent experience of pain results in both a physiological and conscious response. Vertebrates display reaction to pain which may modify behaviour. Emotional responses can include fear, aggressiveness, future avoidance or even depression. Physiological responses may include limping, respiratory changes, defecation, pupil dilation, ceasing to eat or drink, excessive sleep or inability to sleep and so forth.
Given it is difficult to measure pain outside of humans (who can verbalise a pain score on top of physical and emotional changes), in animals it is accessed by the other common indicators. For example, measuring heart rate, observing any favouring of certain positions or movement, reluctance to move and respiration rate can all be indicators of the degree of pain being experienced. However they may also have covert signs which are difficult to detect.
Prey animals will show less overt signs of pain than predators. This means that a mouse, rabbit, guinea pig or any other vertebrate prey will potentially experience a lot more pain than it displays outwardly. Unlike predators who typically have a greater ability to externalize signs of distress. This could lead to a false belief that a prey animal in with the reptile that is attacking it is not experiencing a great deal of pain.
So regardless of the degree of pain, we already know that vertebrates feel pain and that the pain is likely to modify behaviour. But what about invertebrates?
There are those who dispute that invertebrate can’t feel pain as they do not have the ability to translate noxious stimulus into emotion. They will move from aversive stimulus which can easily be seen by placing a snail on hot pavement or poking an insect with a pin. But that can simply be a reflex without suffering, it is not enough evidence of the ability to feel pain.
Three commonly believed reasons that invertebrates are incapable of feeling pain involve evolution, nervous system and behaviour. First let’s look at the function of pain in evolution. Because invertebrates have a short life span it is unlikely that it serves any useful purpose within their evolution. Second the neural capacity of invertebrates, with the exception of cephalopods, is limited with small brains and nervous systems thus they do not have the cognitive capacity which is considered a prerequisite for the development of emotional responses. Third the behaviour of invertebrates does not support the theory of being able to feel pain. It has been observed that after injury, an insect will continue its normal behaviour such as with a locust that will continue to eat while being eaten by a praying mantid or an insect with a damaged limb will not avoid putting pressure on it or alter its movements which are expected to be indicative of pain.
There is not enough research to really be able to confirm that insects do not feel pain and therefore provide support or not to the case of using them as live food. Although science has now found that the fruit fly has a neurotransmitter as is in humans.
Regardless, until proven otherwise, it might be difficult for a reptile owner to believe that insects do feel pain as defined here when you observe the behaviour of a cricket sitting on top of its predators head quite happily trying to turn the tables on who is eating who. If pain is to include an emotional response then it is expected that it will include avoidance of the predator, not advancement.
In summary, vertebrates feel pain and even if laws do not control the management of feeding live prey, the internationally renowned “Five Freedoms” by FAWC (Farm Animal Welfare Council) should be applied. Vertebrate should be humanely killed before being fed to the predator.
Most zoos around the world (with the exception of China) successfully feed their predators with dead prey. The only real justification to feeding live prey lies with those caring for animals that will be released back in the wild, animals being rehabilitated. Since exotic pets are not to be released the feeding of live vertebrates is not required. Some reptile owners claim that their pet will not take dead prey. These owners could benefit from some training in how to successfully perform this procedure. Contacting local zoo’s, vets and other experts may assist.
In the practice of feeding insects live, there is no evidence at this stage found to support that they feel pain. Although care should be taken regardless to ensure that the insects wellbeing is attended to prior to feeding if for no other reason than because there is no hard evidence yet that they don’t feel pain.