- Joined
- Mar 17, 2003
- Messages
- 662
Phil et al,
The purpose of feeding the H. lunulata to the O. scyllarus was part of a larger line of study examining coevolutionary arms races. In particular we are interested in how predator and prey interact and deal with various offensive and defensive morphologies and behaviors. The animals were not put together for our entertainment. I wanted to ask a fairly basic initial question - would a stomatopod that occurs sympatrically with a blue-ring attack it? We generally think that the coloration of blue-rings is aposomatic, but aside from people usually avoiding them because they recognize the blue-rings and have been told by other humans that they are dangerous, I know of no data that that demonstrate that the blue rings serve as a warning to any other species that might play the role of "predator". The next question to ask if there was avoidance would be whether this behavior was learned of innate? Similar research has been done on other aposomatic systems such as mot-mots and coral snakes, yellow-bellied sea snakes exposed to predatory fish or herons and egrets, etc. It has not been done with blue-rings. Making the question even more interesting from an evolutionary perspective is the fact that both H. lunulata and O. scyllarus have indeterminate growth so it is possible for their interactions to vary with different size relationships - large stomatopods might be able to kill and/or eat smaller blue-rings and large blue-rings might be able to prey of smaller stomatopod. This could considerably complicate the dynamics. It would seem more difficult for an innate avoidance to evolve under these circumstances or even possibly a learned one.
So where do you start exploring such a question. I would prefer to make my initial observations in the field watching blue-rings and stomatopods interact, but such observations are extremely difficult and even if you are persistent and patient enough to see a few encounters, you have little control over the participants, their size, physiology, motivation, experience, etc. Aside from those who are opposed to carnivores killing and eating prey, I assume most people would not object to this type of research. Bringing the animals into the laboratory gives us much more control over the interactions. First, I can control the predator making sure that it is hungry my depriving it of food for a specified period, making sure that it is not approaching a molt, etc. If it doesn't attack the octopus, I know that it is not simply avoiding the blue-ring because it isn't hungry. It is also easier to control the size relationship between the two and to assay the blue-ring to determine how much TTX it contains and/or delivers. (The former is done through chemical analysis; the later by giving the octopus a live grass shrimp, waiting a prescribed period after the initial attack, removing the shrimp and analyzing it to see how much TTX it contains.)
While the intereaction was staged, it was done in a very large tank (200 gal) with lots of rock into which the participants could escape. The stomatopod did have a pvc burrow, but it would have an even better one in the field.
When I presented the blue-ring to the stomatopod, I expected one of three outcomes. Most likely I thought, the stomatopod would flee or simply ignore the octopus. If so, I was interested to see if the blue-ring would also flee, do nothing, or attack (but these are different questions from what I was primarily interested in.) Alternatively, the stomatopod could attack driving off or killing the blue-ring. The third alternative, which I did not expect, was that the stomatopod would kill and eat the blue-ring.
As you saw, the later happened. What you did not see was that the stomatopod continued to pound the octopus for about 25 minutes, long after it was initially disabled, and then killed. Several times during this period, the stomatopod appeared to sample the octopus, jumped back and extensively cleaned its mouth parts. Finally, it ate the entire corpse. We watched the stomatopod for several days and it seemed no worse for the meal. When offered another blue-ring, it also attacked and ate it suggesting that it had not learned to avoid them. In fact, there seemed to be no reason to.
What is interesting here is the behavior of the predator. I've watched stomatopods kill and eat other species of octopus and I had never seen this extended period of processing. This suggested to me that the O. scyllarus was mechanically removing the TTX containing venom from the dead blue-ring by repeatedly pounding and manipulating it. Of course there also remains the possibility that some stomatopods such as O. scyllarus have evolved resistance to TTX, perhaps by modification of their sodium channels as has occurred in garter snake populations that prey on TTX containing newts. We are indeed conducting the obvious experiments of feeding predators pieces of shrimp injected with TTX, injecting TTX directly into stomatopods, etc. However, to test the mechanical processing hypothesis, we have to measure the TTX contained in a prey animal before and after a stomatopod has processed it. Further questions would then consider whether the processing behavior is learned or innate, what happens as the size of the prey approaches that of the prey, are small O. scyllarus resistant to attacks by predatory blue-rings, etc. If it turns out that O. scyllarus are resistant to TTX, then we would like to know if this occurs in other species that occur with or do not occur with blue-rings.
I see this as a legitimate and ethical line of research. Clearly there are issues related to any research involving predator - prey relationships. We try to minimize the number of animals used and certainly try to avoid threatened species, etc. However, often the question dictates what species are used. In this case, it happens to be blue-rings - not because they are "beautiful", but because they contain TTX and have what appears to be aposomatic coloration and we would like to understand how such systems coevolve and function.
I do not stage "cock fights" to satisfy my own or anyone else’s desire to be titillated. I have advised on various nature films that may have included fighting and predation sequences, but in that context neither I or my science have been attacked. In fact some of the same people who seem so affended by this sequence have praised those very films.
(By the way, I was not an advisor on "Incredible Suckers" although I have worked with Mike several times and I've discussed the H. fasciata sequence with him. The blue-ring - stomatopod encounter was staged in an aquarium, was between a blue-ring and stomatopods that do not occur together, and came to a conclusion that I think was not justified. If you look carefully at the sequence, there are at least two different stomatopods used. The first one injured the octopus and was replaced by the second. The story told was that blue-rings release venom to kill prey at a distance. This has not been fully documented and our attempts to replicate it have failed. I suspect that in this case if the stomatopod was killed by venom, it was probably because the injured octopus was "leaking" saliva due to being stabbed.)
O.K., I've rambled on long enough. I can take personal criticism, but when people feel that they can attack the quality of science being conducted in my laboratory, I take it personally. It was clearly a mistake to post that clip and I will do my best to have it purged from the web.
Roy
The purpose of feeding the H. lunulata to the O. scyllarus was part of a larger line of study examining coevolutionary arms races. In particular we are interested in how predator and prey interact and deal with various offensive and defensive morphologies and behaviors. The animals were not put together for our entertainment. I wanted to ask a fairly basic initial question - would a stomatopod that occurs sympatrically with a blue-ring attack it? We generally think that the coloration of blue-rings is aposomatic, but aside from people usually avoiding them because they recognize the blue-rings and have been told by other humans that they are dangerous, I know of no data that that demonstrate that the blue rings serve as a warning to any other species that might play the role of "predator". The next question to ask if there was avoidance would be whether this behavior was learned of innate? Similar research has been done on other aposomatic systems such as mot-mots and coral snakes, yellow-bellied sea snakes exposed to predatory fish or herons and egrets, etc. It has not been done with blue-rings. Making the question even more interesting from an evolutionary perspective is the fact that both H. lunulata and O. scyllarus have indeterminate growth so it is possible for their interactions to vary with different size relationships - large stomatopods might be able to kill and/or eat smaller blue-rings and large blue-rings might be able to prey of smaller stomatopod. This could considerably complicate the dynamics. It would seem more difficult for an innate avoidance to evolve under these circumstances or even possibly a learned one.
So where do you start exploring such a question. I would prefer to make my initial observations in the field watching blue-rings and stomatopods interact, but such observations are extremely difficult and even if you are persistent and patient enough to see a few encounters, you have little control over the participants, their size, physiology, motivation, experience, etc. Aside from those who are opposed to carnivores killing and eating prey, I assume most people would not object to this type of research. Bringing the animals into the laboratory gives us much more control over the interactions. First, I can control the predator making sure that it is hungry my depriving it of food for a specified period, making sure that it is not approaching a molt, etc. If it doesn't attack the octopus, I know that it is not simply avoiding the blue-ring because it isn't hungry. It is also easier to control the size relationship between the two and to assay the blue-ring to determine how much TTX it contains and/or delivers. (The former is done through chemical analysis; the later by giving the octopus a live grass shrimp, waiting a prescribed period after the initial attack, removing the shrimp and analyzing it to see how much TTX it contains.)
While the intereaction was staged, it was done in a very large tank (200 gal) with lots of rock into which the participants could escape. The stomatopod did have a pvc burrow, but it would have an even better one in the field.
When I presented the blue-ring to the stomatopod, I expected one of three outcomes. Most likely I thought, the stomatopod would flee or simply ignore the octopus. If so, I was interested to see if the blue-ring would also flee, do nothing, or attack (but these are different questions from what I was primarily interested in.) Alternatively, the stomatopod could attack driving off or killing the blue-ring. The third alternative, which I did not expect, was that the stomatopod would kill and eat the blue-ring.
As you saw, the later happened. What you did not see was that the stomatopod continued to pound the octopus for about 25 minutes, long after it was initially disabled, and then killed. Several times during this period, the stomatopod appeared to sample the octopus, jumped back and extensively cleaned its mouth parts. Finally, it ate the entire corpse. We watched the stomatopod for several days and it seemed no worse for the meal. When offered another blue-ring, it also attacked and ate it suggesting that it had not learned to avoid them. In fact, there seemed to be no reason to.
What is interesting here is the behavior of the predator. I've watched stomatopods kill and eat other species of octopus and I had never seen this extended period of processing. This suggested to me that the O. scyllarus was mechanically removing the TTX containing venom from the dead blue-ring by repeatedly pounding and manipulating it. Of course there also remains the possibility that some stomatopods such as O. scyllarus have evolved resistance to TTX, perhaps by modification of their sodium channels as has occurred in garter snake populations that prey on TTX containing newts. We are indeed conducting the obvious experiments of feeding predators pieces of shrimp injected with TTX, injecting TTX directly into stomatopods, etc. However, to test the mechanical processing hypothesis, we have to measure the TTX contained in a prey animal before and after a stomatopod has processed it. Further questions would then consider whether the processing behavior is learned or innate, what happens as the size of the prey approaches that of the prey, are small O. scyllarus resistant to attacks by predatory blue-rings, etc. If it turns out that O. scyllarus are resistant to TTX, then we would like to know if this occurs in other species that occur with or do not occur with blue-rings.
I see this as a legitimate and ethical line of research. Clearly there are issues related to any research involving predator - prey relationships. We try to minimize the number of animals used and certainly try to avoid threatened species, etc. However, often the question dictates what species are used. In this case, it happens to be blue-rings - not because they are "beautiful", but because they contain TTX and have what appears to be aposomatic coloration and we would like to understand how such systems coevolve and function.
I do not stage "cock fights" to satisfy my own or anyone else’s desire to be titillated. I have advised on various nature films that may have included fighting and predation sequences, but in that context neither I or my science have been attacked. In fact some of the same people who seem so affended by this sequence have praised those very films.
(By the way, I was not an advisor on "Incredible Suckers" although I have worked with Mike several times and I've discussed the H. fasciata sequence with him. The blue-ring - stomatopod encounter was staged in an aquarium, was between a blue-ring and stomatopods that do not occur together, and came to a conclusion that I think was not justified. If you look carefully at the sequence, there are at least two different stomatopods used. The first one injured the octopus and was replaced by the second. The story told was that blue-rings release venom to kill prey at a distance. This has not been fully documented and our attempts to replicate it have failed. I suspect that in this case if the stomatopod was killed by venom, it was probably because the injured octopus was "leaking" saliva due to being stabbed.)
O.K., I've rambled on long enough. I can take personal criticism, but when people feel that they can attack the quality of science being conducted in my laboratory, I take it personally. It was clearly a mistake to post that clip and I will do my best to have it purged from the web.
Roy