Diet/Feeding: Like hagfish, synx are parasites who will also eat any animal weaker then they. However, unlike hagfish, synx do not rank as 'opportunistic parasitoids' because they actively hunt. There are many creatures that exist as both active predators and active parasites in their nebula, and given the lack of vegetation such a place possesses, this is as close to being "omnivorous" as their specialized food chain gets.
As a predator a synx is not the most physically capable animal, so they instinctively and intelligently go after the weakest of the herd: the young. When unable to ghoulishly envelop these perfectly packaged meals, they seek larger animals who show visible signs of illness or injury. If too large or cumbersome to cram inside, the synx will externally digest this food or pull it apart; like a child dismantling a doll. If the later, the limbs are eaten first so that the torso can be kept alive for a second meal. To call this death traumatic is an understatement, but the younger meals don't have it any easier. Seeing a large, horrifying white eel swallow down a screaming child is the most abominable and horrific scene one can imagine, an act made all the more gruesome by it's seemingly cartoonish appearance. Given their draconian preference for food freshness, it should come as no surprise that any synx dispatched after a recent feeing usually has a live (albeit not intact) occupant inside it.
Understandably, these eels have a great deal of trouble fleeing after engorging themselves. Like a small bird with a large fish inside, a synx will periodically pause in movement and collapse around itself to try and settle it's animated gut. Being so inelegant, this is when synx are caught and slain the most. The digestive secretions of a synx are nearly identical to what you would find in a terrestrial shark, which isn't very impressive in the scale of galactic fauna. It is however more then enough to deal with a human body, skeletal remains and all (given time).
Once the food has adequately stewed in gastric soup, their appendage that resembles a tail wraps around and constricts their own abdominal cavity: compacting, crushing and kneading any solid material left into paste. What remains in the stomach thereafter is then fed into the same "tail", which is actually an extension of their abdomen; housing all their intestines and other entrails.
As a parasite a synx can survive in the entrails of nearly any large predator that has a preference for live or otherwise fresh meat. The synx will steal the largest portion of the predator's intake, and like the ghoulish things they are; eat any live food that happens to be sent down. Depending on the size of the predator the synx is inhabiting, the detrimental health effects that come of this may arrive sooner then later. In either case, once it becomes clear the predator can no longer be used as a host, the synx will consume the host itself, from the inside. With jaws not having the capacity to chew and being relatively inadequate at tearing, the synx burrows into muscle tissue and folds its own stomach inside out; slowly liquefying all the soft flesh making contact with this organ. The exposed and tubular digestive cavity also acts as a straw which they use to drink the spoils of their efforts. When hunting, synxes will use this method to consume un-ingestible or unreachable food items. An anxious or starving synx will exhibit this behavior out of sheer excitement or jubilation, involuntarily and reflexively expelling their stomachs during the feeding process.
This internal/external digestion continues until the predator dies. Once decomposition has begun, the synx immediately vacates the hollowed body to avoid the coming dangers. The bacteria inside the gut of every synx is the most important component to making alien flesh safe for them to eat. These microbes evolved over millions of years along their synx hosts; which jumped from one colossal life-form to the next, always encountering strange new aliens as their only food source. However in the nebula of synx origin, the decomposition of animal life is very different from life outside the nebula. The natural decomposition process of most world's biota is simply too alien for a synx's biology handle, and can be lethal to the organisms that live in their gut.
Any organic matter a synx consumes must be submerged in their stomach bacteria before it has begun to rot, otherwise the flesh will not properly digest and the synx will experience toxic reactions of various degrees. It should be noted that these eels have an equally violent reaction to rotting flesh on the outside of their body as well.
When first arriving in new intolerable environments, it is common for a synx to be draped in dead animal tissue. In a display of genuine ingenuity, this flesh was swallowed before rotting and regurgitated before mastication. Aside from protecting against sunlight and air contaminants, these coverings are soaked with their own gut bacteria, giving them biological shields to drape themselves in. This helps synx progressively adapt to the more minor threats around them, essentially making their wardrobe a natural immunization. This adaptation is not lost on the sapient species aware of synxes, and many scientific and medical breakthroughs have been achieved from harvesting the organisms that live inside the gut of these creatures.