In order for a species to exist independently it must have several capabilities and must be inclined to use them (you call these inclinations "instinct"). These include: the ability to obtain energy from readily available materials, the ability to gather and consume those materials, the ability to withstand the rigors of its environment and to survive any threats that environment poses, and the ability to reproduce.
The animate life forms on your planet (as is still the case in the rest of the universe) originally gathered all their energy by consuming inanimate life forms. This involves very complex biochemical processes that actually perform some level of molecular engineering. Since time was critical to our work (your population was rapidly expanding and your understanding of the world around you increasing even more rapidly) the boss ordered that we not seek to duplicate all those complex processes in the new species we would engineer.
We had to agree that the boss's solution was necessary, even though we didn't like it. He said that other animate life forms had done the molecular conversions. If our new species consumed them the process of extracting needed chemicals from the consumed matter would be greatly simplified. So in engineering each new life form, we gave them the tools necessary to devour other creatures.
At first we thought that we could get away with equipping our new life forms to consume animals that had died from other causes. The boss let this continue for several years before he ordered that most of our work must focus on giving the new species the capacity to capture and consume living prey.
We protested, but the boss adamantly refused to hear us. We had already adapted existing crushing and grinding structures into sharper devices that could cut and tear flesh. Now we adapted existing protective structures into sharp grasping devices that could help prevent a captured animal from escaping before it could be consumed.
While I worked in the sea creature section, I familiarized myself with the work of other sections. This was one of the boss's directives. We performed modifications on all classes of animals, but the greatest project on land involved reptiles. (This had something to do with the boss's original failed plan, but I learned the specifics second hand. At any rate it's all very complicated and I haven't the time or space to deal with such issues here.)
On my specific project, making these modifications was somewhat more complicated. Fish do not have limbs in the sense that land creatures have, so it would have been difficult to modify them to grasp prey. We would have to put all the grasping and cutting tools in the mouth. After generating several species that were not viable I learned that these structures would have to be frequently replaced during the life of the creature. The existing genetic code did not allow for such frequent replacement.
After several more unsuccessful attempts I stumbled on the exact genetic code I needed. I found it in the very fish I was trying to modify. It didn't involve the usual mouth structures, but replaced the scales that protected the fish's body. These also required frequent replacement. Once I discovered that, my task was simple. I would extend the area covered by scales into the mouth. Then I would modify those scales to be composed of much harder material.
The part of the modification I was most proud of was that as the new ones developed at the inside of the mouth they pointed inward. Thus the thrashing of the prey would serve to move it farther inside the mouth of my fish. As they grew larger they would point up and even a little bit out, providing the needed cutting ability.
The original flat structure was graceful, but slow. I streamlined the body and returned the fish to the usual caudal fin propulsion. Through successive generations I developed a sleek, fast, and efficient creature. As part of our experimentation I made both large and small forms of this animal. It was here that I first encountered interference.
The angels that remained loyal to the master modified the largest of my creatures so that they consumed the sea's counterpart to land plants. Whenever I tried to undo those modifications they forcibly stopped me. I reported this interference to the boss. He went directly to the head of the other angels to complain. He returned in a very bad mood and I avoided him studiously for several months thereafter.
I was too fearful to ask what had happened and the issue never came up again. I learned later that the other sections of our squad had encountered similar interference. Indeed these angels (who do outnumber us) have hindered or even halted outright some part of every operation we have undertaken.
All during this time we also experimented on another modification suggested by a colleague. He had learned that the land animal section had modified a mammal so that it laid eggs rather than giving birth to live young. Could we do the opposite with our fish, he wondered. He took charge of most of those modifications. As an interim step he developed species that would retain their eggs in utero until they hatched. Over time he succeeded.
There was one unexpected development. In one species the inclination to capture and eat became so strong so early that it became active before birth. This species rarely gave birth to more than one young at a time because that one had already consumed the others while they were still in the womb. I wanted to fix the problem, but the boss stopped us. He said he found it amusing. I certainly did not understand that.
As I mentioned earlier, we accomplished most of these modifications through direct molecular manipulation. As you can imagine this required a lot of tedious, hands-on work. We had to do the manipulation on developing fetuses so our changes would become part of the animal's structure. And we had to do them twice; once for each gender so our new species could reproduce.
Someone in the land animal section of our squad dreamed up an ingenious method for introducing genetic changes into an animal. He modified the DNA in the lab, built a protein shell around it and provided it with a mechanism for introducing its DNA into a living cell. The resulting device was not at all alive. But it could convince a living cell to make copies of itself so that, in a crude sense, it could reproduce. As the new string of DNA became part of the cell, and as the copies invaded other cells, the modifications could become part of the whole animal.
These copies would, of course, be floating around in the animal's body fluids and could be passed from one individual to another. Through this mechanism we could perform a single manipulation, introduce it into one animal, and have it spread to a rather wide population in a short time. You have invented the word "virus" for this mechanism. The bioengineering squad has adapted it to accomplish other purposes. But that goes beyond the scope of this chapter. I shall discuss that in a chapter of its own later.