I have designed a new creature, which I feel would best be introduced simultaneously with the Lighting arc. It is a rather large and quite dangerous ambush predator with photophobic tendencies, so I feel justified in naming it a "grue". It differs from the 'canon' grue in its amphibious nature and its highly distinctive third eye, but from a dwarf's point of view, they are functionally identical. (Canon grue: If you encounter a grue, you're dead. My grue: If you encounter a grue, you're pretty much as good as dead.) My grue can be summarized as an alligator that you have to fight while you're blind and drowning.
Eyes with a reflective retina to help gather dim light are very well-known in the real world, and bioluminescence is nothing new either. But when you place those bioluminescent cells INSIDE an eye with a reflective retina, their brightness is doubled by the mirrored backing. Add a lens for focusing that light into a beam, and suddenly you have a creature with a headlight, of an intensity far exceeding anything else in the biological world. Such an eye would be useless for vision, of course, but if the animal has at least one *other* eye to see with, then it has a darkness adaptation like none other.
After hatching from their eggs (laid in cavern pools & streams), grues start their lives as, essentially, fish. Their pectoral and ventral fins are all lobed (the better to stir up the bottom sediment and hopefully dislodge prey), and their long tail is distinctly eel-like. The skull is fairly long and narrow, covered in large (albeit thin) bony plates, with one eye on each side of the head for all-around vision, and one more facing straight up on the top of the cranium. All three have reflective retinas for better vision in dim light, although the central eye is even more sensitive than the others in that respect. The grue has both gills and lungs: both are located inside the thorax, and are visible externally only as two pairs of slits, one at the start of the ribcage (intake) and the other at the end (outflow). Both the lungs and their orifices ride high inside the dorsal part of the body, while the gills are similarly situated very low--this ensures that even when the grue is in extremely shallow water, its gills are still submerged. The young grue's lungs are still rather poorly developed, so its movements on dry land are slow, awkward, and interrupted by periods of rest. When not stirring up the streambed to find prey, or shambling on land in search of plants, the grue uses itself as bait to attract unwary animals, particularly sighted creatures that wandered into the caverns by mistake: Upon finding a particularly dark & gloomy pool, the grue will lie at the bottom and activate its bioluminescent cells, which are arranged in clumps along its spine, and use its central eye to keep a close watch for animals descending from the (slightly) brighter shallows, drawn to investigate the twinkling down below. It plays a similar trick on land dwellers, playing dead at the shoreline (gills below water, lungs above) and faintly flickering until an animal of the appropriate size for lunch gets too close.
The grue spends from 1 to 2 years in its young, "fish" stage, depending on nutrition, eventually reaching a size from 20,000 to 30,000. It then spends about a year metamorphosing into its immature, "amphibian" stage, actively hunting the entire time. The cervical vertebrae lengthen, pushing the head away from the body & giving the grue a neck. The rearmost ring of bony plates protecting the head detaches from the skull and remains on the torso, where the bones thicken and become attachment points for the new muscles growing on the pectoral fins, which extend and develop wrists & elbows, while the fins themselves solidify into webbed feet with tiny claws. The ventral fins undergo a similar process, although these feet are more thoroughly webbed and lack claws, and the grue's new hindlimbs are shorter & not as well muscled as its forelimbs. The lumbar vertebrae fuse together and grow into a pelvic girdle, and the tail becomes shorter & thicker, losing its ventral fin but keeping the dorsal one. The rearmost section of the grue's head, meanwhile, changes shape, becoming taller & broader. This has the effect of turning all 3 eyes into more forward-facing positions, giving it a narrow slice of binocular vision. It is only BI-nocular vision because, in the transition, the phosphorescent clusters of cells in the grue's skin invade its central eye, largely blinding it even when they're not actively glowing. When the cells ARE glowing (which the grue can control by regulating blood flow to that eye), the grue's immediate surroundings are bathed in a dim, ambient light, ideal conditions for the grue to snap up any creature unfortunate enough to lack eyes. The grue's lungs develop rapidly in the first metamorphosis, becoming just as efficient as the gills, making the immature grue the most truly amphibious, as well as the most omnivorous, of its 3 life stages.
After another 1 or 2 years spent as an "amphibian" (reaching a size anywhere from 100,000 to 150,000), the grue takes about a year to mutate into its adult, "reptile" form. The neck lengthens again, allowing a slightly greater range of strikes, and the limbs gain increased size & strength, with heavier claws on all 4 feet. The webs between the grue's fingers & toes diminish, leaving its swimming capabilities almost entirely powered by its tail--which again becomes heavier, roughly triangular in cross section, although it maintains its strong dorsal fin-ridge. The grue's body scales become thicker & heavier, allowing it to take far more punishment in a stand-up fight--and the grue can now actually stand up, thanks to its stronger pelvic girdle, using its tail for support while it slashes with its forelimbs. The grue's lungs keep pace with its overall growth during its 2nd metamorphosis, but its gills do not--they remain at their 2nd stage of growth permanently, hampering its underwater activities. The rear part of the head broadens again, pointing all 3 eyes almost completely forward, providing a broad stripe of true binocular vision, with sharply directed illumination. The socket of the 3rd eye deepens, and the shape of its lens alters, focusing the majority of its light into a concentrated forward beam, as bright as looking directly at a burning torch. The nictating membranes covering all 3 eyes become thicker and opaque (a side effect of the hardening scales), so the grue can now effectively blink. It takes full advantage of this by waiting for prey with its third eyelid tightly closed. When its victim approaches, the grue causes its eye to start glowing, and then a moment before it strikes, it constricts the pupils in its sighted eyes, and then opens its 3rd eyelid, shining its powerful light directly in the surprised victim's face. The targeted creature either has eyes--in which case, it is temporarily blinded by the sudden glare--or it does not; either way, the grue can see while its prey cannot, making for an easy kill. After spending 4 to 6 years as an adult, and reaching a maximum size of 275,000 to 400,000, the grue dies of old age.
On light: Unlike their 'canon' counterparts, my grues do not actually fear light--they simply know that ambient light robs them of their biggest advantage in hunting. Hungry grues will avoid light sources unless sorely pressed, but it is not unusual to see a well-fed grue sharpening its claws directly on the trunk of a phosphorescent tree. Occasionally, grues will deliberately attack and destroy light sources, uprooting & sometimes even burying bioluminescent saplings, to make their hunting territory more hospitable (to them, at least). Despite these behaviors, grues should not be mistaken for intelligent animals--they operate purely on instinct. Just as with canon grues, the best safety precaution against grues is simply to carry a torch or lantern. They do not recognize weapons or armor, a grue only calculates ambient light and the intended victim's size (which can be greatly exaggerated by jumping shadows) so a Cheesemaker with a candle is viewed as a bigger threat than an Axelord without one.
Disadvantages, behaviors, and other notes: Due to the construction of its shoulders and wrists, a grue can turn its "hands" to face forward, down, backward, and outwards--but not up or inwards. As its palms cannot face each other, and because it lacks opposable thumbs, the grue cannot grasp with anything but its mouth, nor can it climb trees. Its teeth are simple and nondifferentiated, so its bite is not as effective as one with specialized piercing & slicing teeth. As the torso contains both lungs and gills, there is less room available for the digestive system--its intestine is relatively short and inefficient, forcing the grue to eat more frequently than might be expected (as a cold-blooded animal, though, its dietary needs are far less than an equivalent warm-blood). On the flip side, because the grue does not breathe through its head, strangling its neck does nothing to impede its oxygen intake--in can, however, stop the flow of blood to its brain. Never a creature known for its stamina, an adult grue simply cannot obtain the oxygen it needs to keep fighting for more than a couple of minutes or so while submerged, due to the stunted nature of its gills. All grues absolutely detest being upside-down, and will do anything to right themselves; even while unconscious, an inverted grue will thrash about until it is right side up once more, although this flailing is limited to the spinal column only, not the limbs. In combat, immature & adult grues tend to favor two strategies: After the initial blinding shock (which only adults can do), the grue makes full use of its amphibious nature, grabbing hold of its victim with its mouth and dragging it towards the waterline, so prey caught on land will have to fight underwater, and vice versa. Alternatively, the grue will use its powerful forelimbs to rake the victim with deep slashes, then simply back off and let the creature bleed out. Grues have zero sense of smell, and only rudimentary taste--their lungs & gills never evolved sensory functions, and again, their mouth is just for eating. Because of this, grues will only eat very fresh kills, as they cannot tell if older meat has gone rotten. Young and immature grues will occasionally indulge in cannibalism, but this behavior abruptly ceases after an adult grue's first mating.
Thoughts?
Yeah, I know that some of this (like grues hating being upside-down) is outside DF's scope of implementation, I just wanted to really nail the flavor of the animal.
[EDIT: Grues don't have noses.]
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Topic: You are likely to be eaten by a grue. (Read 2415 times)