Khezu/Red Khezu Ecology

Blind cave-dwelling Flying Wyverns covered with a pale white hide which is kept constantly moist with mucus secretions. Upon closer inspection, their translucent skin allows many blood vessels underneath to be visible. As they normally inhabit cave environments, their eyes have regressed but their sense of smell is well-developed. Their rounded head lacks many of the usual external features found on other monsters, but they do have a horrific-looking maw with rows of large triangular teeth. Their necks can extend to extraordinary lengths to catch prey, which is attributed to a specialized structure and musculature in combination with flexible stretchy skin. While they possess winged forelimbs like most Flying Wyverns, they are poor fliers [due to their short wings and fat tubby body]. However, they have adhesive pads on each of the two fingers on their wings and on their three-toed hindlimbs which allow them to scale cavern walls with ease. Moreover, their strong hindlimbs allow them to leap onto cave walls and ceilings with a single pounce. As another adaptation, their short stubby tails end in a mouth-like orifice ringed with teeth that can expand and adhere to surfaces like a suction cup, allowing them to hang from cave ceilings. 

Khezu are well-known for their electrical abilities. They are able to emit electricity from its entire body, and will couple this ability together with their pouncing and charging attacks when enraged. As a ranged attack that paralyzes prey, they can launch lightning balls from their mouths as well. Three smaller lightning balls can be released simultaneously which spread out in front of the monster by moving across cave floors or even along cave walls. Alternatively, from a hanging position on walls or ceilings the Khezu can hurl or drop a single larger lightning ball. If they are stationary while performing an electrical attack, they will ground themselves using the suction cup on their tails [to release excess electricity, as they do not have specialized structures like spines or fur for storing it]. *The large amount of fat in their body may also insulate and protect them from their own electric shocks.*

Seemingly able to inhabit any sufficiently large cave system, Khezu are found in a wide variety of different locales including polar environments, snowy mountains, temperate swamps and tropical jungles. Some reports indicate that Khezu found in colder areas will migrate to warmer areas during winter. Besides that, it is said that Khezu prefer inhabiting areas close to active sources of water, perhaps to help conducting electricity into prey or to ensure that their skin remains moist. In snowy areas, their white hide actually camouflages them when they venture out of caves for whatever reason.

As prey is scarce in caves, Khezu likely feed on anything they can catch and kill, and the large amount of fat stored in their body may help them survive for longer periods of time between feeding. With low visibility in the caves, Khezu are at a major advantage with their excellent senses of smell and hearing. *Experiments conducted on captive Khezu suggest that they are able to detect live prey through electrolocation or some other ability without using their senses of smell and hearing, but no concrete conclusions have been made.* Normally, they feed on Herbivores that may enter caves for shelter such as Kelbi, Aptonoth and Popo. They could potentially easily prey on small Bird Wyverns [and Ceanataurs too, especially given the latter's weakness to electrical attacks.] Although they prefer feeding on live prey, they will scavenge carcasses as well. The saliva of a Khezu is highly acidic helping it to completely digest its prey. When hunting larger or more dangerous prey, they will opt to incapacitate them with their electrical attacks before pouncing on them. For smaller prey, they usually remain motionless while extending their neck to catch prey and swallow them whole. However, the Khezu's neck will lose its elasticity and start to droop with age, resulting in the monster being unable to feed and eventually dying from starvation. 

In combat, Khezu are not particularly mobile, but are capable of bursts of speed when pouncing on prey. This may stem from their fat bulky bodies and/or from the fact that they rely heavily on their sense of smell to locate enemies, which is slower than using sight or hearing. Aside from the techniques they typically use in capturing prey, they will use their tails as whips while fighting like many other wyverns. They are also known for their nightmarish roar, which they often use repeatedly in battle. [It's possible that they use the reverberations of their cave habitats to amplify the roars to further terrify and stun opponents.] While most creatures would not normally hunt Khezu due to its potent electrical abilities, the Shrouded Nerscylla hunts Khezu and wears its hide on its body. It is speculated that they hunt Khezu as their hides help them to retain moisture in their desert habitats.

Another unusual aspect of the Khezu is their reproductive biology. Since a single cave system may only be able to support one Khezu, it is rare for Khezu to encounter another one of its own kind. As a result, they have evolved to become hermaphrodites capable of reproducing without the need of a mate. When they breed, they will paralyze a medium-sized Herbivore like Aptonoth or Popo to use as a host. The eggs that are then deposited on the paralyzed monster will hatch into whelps that will feed internally on the host as endoparasites. After reaching a certain size, the whelps will emerge from the host and conceal themselves in places like tight crevices to ambush their next victim. At this stage of their life cycle, they behave as ectoparasites instead. It is also interesting to note that the orifice at the end of a Khezu's tail functions as a mouth for whelps to feed on blood.

The closest relatives of the Khezu are the Gigginox, which share a similar lifestyle.

Red Khezu are an uncommon or rare Subspecies of Khezu with a blood-red hide. Its is said that Red Khezu are normal individuals, while "regular" Khezu are actually albinos. Despite that, the red coloration makes them stand out more than standard Khezu, which decreases their chances of survival. [Since they still dwell in caves most of the time like standard Khezu, this is not as much of a detriment to them as it is to Subspecies like Azure Rathalos and Pink Rathian, which are extremely rare as a consequence.] Regardless, the Red Khezu that have survived to adulthood are more powerful than regular Khezu, possessing more muscle mass and improved control over their electrical abilities and neck-thrusting attacks. The elemental weaknesses of their hide differ from their regular counterparts as well. While they are found in the same environments as regular individuals, it is reported that they can overwinter even in colder areas due to their increased body mass.

Monoblos/White Monoblos Ecology

Herbivorous but highly aggressive desert-dwelling bipedal Flying Wyverns that are named for their giant singular nose horn. Monoblos greatly resemble their close relatives the Diablos, possessing the same heavily armored body structure with powerful muscles adapted for digging. Nonetheless, there are a number of differences. Unlike the broad frills of Diablos, Monoblos have elongated frills extending above their head instead of sideways, which are similarly used to push away obstacles while digging. [Their larger frills may help them compensate for their singular nose horn which is not as adapted for digging as the twin horns of Diablos.] These frills have long parietal spikes extending from their edges, with the longest spikes located on the top of the frill. A pair of jugal horns also extend from their cheeks and three pairs of spikes protrude from their armored backplate. These features make them appear more intimidating, and their frills can be flushed with blood especially when enraged. The spikes on their neck frill and back, as well as their giant nose horn have a reddish tinge that is most apparent after they have been properly cleaned. Furthermore, Monoblos have tail clubs similar to that possessed by Rathalos, with four pairs of thagomizer spikes protruding sideways and a singular spike at the tip, instead of the hammer-shaped tail club of Diablos. Lastly, even though Monoblos have a herbivorous diet of cacti similar to Diablos, they have very different beaks. Monoblos has a thinner pointed beak and their mouths have cheeks [which allow them to actually chew unlike Diablos.]

Like Diablos, Monoblos are feared since they are extremely territorial and aggressive towards other monsters in their habitats, even herbivores, since food sources are limited in the desert. When provoked, they will release an ear-splitting screech of a roar. They will even huff black smoke if truly enraged, similar to Diablos. As mentioned above, they will also flush their frills with blood. Genprey packs and their Gendrome alphas, as well as Cephalos packs and Cephadrome leaders often fall victim to the their vicious rampages. Even large predators like the ferocious Tigrex give them a wide berth. If not charging at their foes at high speed with their powerful legs, they tunnel underground to ambush enemies from below. They will use their spiked tail clubs in combat as well. Despite that, it is worth noting that Monoblos are said to be less aggressive than Diablos. [It's possible that they're less territorial because their dentition and jaw structure allow them to process their food better and survive with less food.] Monoblos are extremely rare however, [potentially because they are still out-competed by the more aggressive Diablos.] For this reason, Monoblos are only allowed to be hunted by solo hunters to protect them from over-hunting. 

Due to their subterranean habits, Monoblos have an excellent sense of hearing but poor eyesight like Diablos. They are similarly highly sensitive to loud sounds like sonic bombs and monster roars, which surprises them and forces them to surface. This disorients and traps in the sand for the time being, but after they find their bearings they will use their wings to take flight in order to free themselves. 

During the breeding season, males will flush their frills with blood to attract females and scare off rivals. It's quite probable that males will fight each other over females like Diablos. However, the females do not undergo a major physiological change as seen in Black Diablos. 

Instead, Monoblos have a rare Subspecies known as White Monoblos due to their chalk-tinted armor plating. The origins of this Subspecies are unknown, as Monoblos are already rare monsters with a small population. White Monoblos have a harder shell and are more aggressive than normal individuals, capable of chaining charge attacks together and charging faster than normal Monoblos.

Diablos Ecology

Herbivorous but highly aggressive desert-dwelling bipedal Flying Wyverns that are named for their huge pair of forward-facing "brow" or supraorbital horns. Diablos are sandy-brown in color, matching the desert sands. Much of their body is covered in tough shell plating except for their undersides and wing membranes, and they even have a thick protruding backplate between their shoulders. [These features may protect them from abrasion when burrowing.] While they are Flying Wyverns, their wings are more adapted for digging than for flight, so it goes without saying that they have poor flight capabilities. Besides their majestic twisted horns, Diablos are adorned with a broad bony neck frill extending behind and to the sides of their heads, which has spikes along its edges. They have powerful muscles throughout their body for digging and use their horns and neck frill to push away obstacles and sand while burrowing, in combination with the blunt claws found on all of their limbs. Surprisingly, Diablos are herbivorous and feed on succulent cacti five to six times per day. Due to this diet, instead of having sharp teeth like most wyverns they have wide beaks with teeth-like projections and a pair of forward-facing tusks extending from the upper jaw. Their tails possess a heavy studded hammer-like club or tailcase that puts steel hammers to shame. 

Feared as desert tyrants, Diablos are extremely territorial and aggressive towards other monsters in their habitats, even herbivores, since cacti are limited in the desert. When provoked, they will release an ear-splitting screech of a roar. They will even huff black smoke if truly enraged. Genprey packs and their Gendrome alphas, as well as Cephalos packs and Cephadrome leaders often fall victim to the Diablos' vicious rampages. Even the ferocious Tigrex give them a wide berth, and they have been observed lifting and throwing the large Brute Wyvern Glavenus using their immensely strong neck muscles during their turf wars. Diablos will commonly charge at their opponents with their powerful legs or tunnel underground before emerging to strike their prey from below. Alternatively, they may use their tail clubs to deal devastating blows. Despite their tremendous strength, they are outclassed by the nomadic Deviljho, which have been witnessed lifting and slamming Diablos onto the ground. While these are not usually predator-prey encounters, as Diablos are still not easy foes to bring down, they will still occasionally fall prey to Deviljho that are hungry and desperate enough. [Juvenile Diablos in particular can still potentially be preyed on a variety of desert predators, though this is where their burrowing abilities may come in handy.]

As Diablos frequently travel underground, they have an excellent sense of hearing but poor eyesight. This has the side effect of making them highly sensitive to loud sounds like sonic bombs and monster roars, which can surprise them and force them to surface. This usually causes them to be disoriented and trapped in the sand temporarily, but eventually they will recover and use their wings to take flight in order to free themselves. In the Wildspire Waste, Diablos spend most of their time in the large underground caves, only venturing outside to feed due to their hatred of loud sounds. 

Most of the time, Diablos are solitary creatures that do not tolerate each other's presence, and will readily lock horns other over territory and food. However, male and female Diablos will pair up for a short period of time during the mating season. It is during these times that male Diablos will fight each other for mating rights. After mating, female Diablos will undergo an even more drastic change from the hormones and eggs in their body, gaining an intense black tinge and becoming the Subspecies known as Black Diablos. While technically not a true Subspecies, they are classified as such due to their increased strength, heightened aggression, intense savagery, thicker hide and providing different materials from regular Diablos. Females are already larger than males, so this only makes them even more terrifying. Besides acting as a warning to other monsters, some researchers speculate that the black color helps them raise their body temperature using the sun and shows other males that they are already taken. Although they will share their territory with their mate for a short time after mating, they cooperate and prefer to wander alone, even fighting each other when encountering each other. Due to this behavior, it is believed that Diablos or either sex do not care for their young at all after her eggs are laid. However, it is worth remarking that Black Diablos tend to feed on different kinds of cacti from regular Diablos for her developing unborn young. Black Diablos also prefers to stick to her territory more, for example in the Wildspire Waste they tend to stay in the underground caves and venture to the surface less often. If a Black Diablos lives long enough after many battles and absorbs enough bioenergy to become a Tempered Monster, her strength and abilities become comparable to an Elder Dragon.

The closest relatives of Diablos are the rare Monoblos, which lead a similar lifestyle.

In heat or pregnant/gravid?

In all of the English in-game descriptions, Black Diablos is described as being in heat. In the official Dive To Monster Hunter World book however, it is stated that they are pregnant(gravid) and gain their coloration after mating to tell other males that they are already taken among other reasons. The Japanese in-game descriptions are less specific and only say that they are in the breeding season (which can include both the intervals when they are in heat as well as when they are gravid). I assume that the translators made an error in the translation for the English description.