How could you go out and kill aN animal that is just minding its own business? It's horrible and inhumane. Granted, putting Animals out of their misery is ok, but
Just doing it for a sports horrible. Why do we need to bother innocent animals that don't even bother us? Killing them is wrong.
Just because an animal is not human does not mean their lives are of any less value. Animals are just as important as people and CAN experience complex emotions despite what some people say. Personally I believe that valuing animals less than humans is no different to valuing other genders or races less than your own.
I believe that we are equal with animals because we all come from the same bussom of Mother Earth. Because of this, we need to protect our fellow species. I would rather have angry butt sex with the devil then to let an innocent chihuahua die in a cruel less world.
In this scenario, I define "wrong" as causing pain and suffering.
First it depends on the species. If we are talking about some microbes or plants, so about individuals without a mind, that are neither conscious nor sentient, then it might would be less worse, because none of these individuals feels anything or is even aware that it is alive. But we also have to think about the impact it would have on the environment. So, while phytoplankton would fit the before mentioned criteria, it would still be worse, since practically all marine live depends on phytoplankton, as well as much of the animals on land, who depends on marine life. Also 50% of all the photosynthesis is conducted by phytoplankton. So its extinction would have severe consequences for the global climate and environment and thus almost all life on earth and would cause many more species to go extinct.
So killing all phytoplankton would be more wrong than to kill all humans.
To make it as little wrong as possible it would have to be a species that no other species depends on, which generally are the ones that are on top of the ecological pyramid. Which are either the top predators in a specific area (tigers in south-east Asia, lions in Africa, polar bears in the arctic etc.) or humans. But while the first play an important role in keeping the ecological balance, we humans do not. We simply reap a place of all its resources until there is nothing left we could use, then we move on. So maybe killing all humans is actually the least wrong thing to do. But then again, we have domesticated so many species, which now depend on us, which would die, too, if we were to go extinct. But if we were to slowly decrease the human population by preventing reproduction,instead of violently killing everybody, then the number of domesticated animals would decrease the same way. Also, most of them are killed for food or other things anyway . So, unless one finds a species, that is completely irrelevant to the the ecology (and also neither sentient nor conscious, at least if were talking about violent killing, instead prohibiting reproduction), than the least wrong species to kill is humanity. Conclusively, it is more wrong to kill another species.
There is not enough of a distinction between animals and humans to warrant a distinction in the morality of killing either living creature. Attempts to make that distinction ultimately fall into the trap of deeming one life worth than another based on certain criteria, which is a dangerous concept to accept.
People are more precious then animals in that they are made in the image and likeness of God and they have superior knowledge and capacity for learning. An animal's life is still precious though and should not be destroyed thoughtlessly and for no purpose. I believe that killing an animal is fine as long as will you use it and not just for the sake of sport.
According to your logic, the genocides such as those caused by Hitler, Stalin, and Mao would be even worse if it had been a mass killing of dogs or cats. Humans can express complex logic and emotions, unlike practically every animal, which possess only the most basic instincts. I've lost faith in society.
I personally would probably save a humans life before i would save another species life. Probably because i have evolved to care more for my own species than other species but even tho i feel this way i can not find any good argument in support of the notion that humans should suffer less than other species and i don't think there are any rational arguments for this notion, only irrational arguments based on emotions.