The Yautja are a hunting race from the furthest reaches of the universe. The males of the species live for the thrill of the hunt.
The Yautja circulatory system can be divided in to 3 circulations:
1. From the heart to the lungs
2. From the heart to the body
3. From the heart to the brain
In the Yautja circulatory system the brain has a separate circulation. This allows for a higher blood pressure in the rest of the body without damaging the fine network of blood vessels in the brain. This allows the Yautja to live with blood pressures that would normally kill a human. The ability to create and survive such high blood pressure has certain advantages. The blood can be transported through the body faster and thus oxygen and other nutrients are transported quicker and waste products are removed faster. This special circulatory system is part of why Yautja are so strong. It allows the organs and muscles to work harder and thus increase the muscles capacity.
The Yautja 3-part heart consists of 2 auricles and 3 ventricles. The blood is pumped from the right side of the heart (seen on the left of the heart schematic in blue) through the lungs. From there it goes back to the heart and into the left auricle (seen on the right of the heart schematic in green). From here it goes in to the 2 ventricles that are connected to it. One pumps it into the body and the other pumps it into the brain at a much lower pressure. When the blood has gone through the body and the brain it goes back to the right side of the heart and the cycle starts again.
The Yautja skeleton is stronger then our own, although the material it's made of isn't stronger then the material our own bone is made of. The yautja skeleton is stronger however because of its firm build. The bones are much thicker then our own and also much more compact which makes them heavier. Yautja don't seem to have the problem of calcification which makes bones more fragile. Whether this is natural or because of the Yautja have a treatment for it is unknown.
The Yautja muscular structure is in construction quite similar to that of humans. The reason Yautja are much stronger is due to the fact that the muscles have a much more efficient nutrient and waste product transport, as well as the much higher gravity on there home planet. This is because of the Yautja 3-part heart. The greater strength is also created by the higher percentage of muscular tissue per kg of body weight and the fact that Yautja are bigger then humans.
Very little is known about the Yautja nervous system; but it is speculated to be similar to that of humans, despite having much faster reflexes.
The Yautja breathe 1% more oxygen and 5% more hydrogen than humans.
Yautja lungs take up oxygen more efficiently then human lungs. This is necessary since Yautja breath an atmosphere which has 2 to 3% less oxygen then our own atmosphere; Their atmosphere is rich in nitrogen and has a high humidity, 70 to 90% humidity is normal. Although yautja can breath the earth's atmosphere they can't breath it for very long, up to 3 days maximum. This is why they always have breathing gear with them. For as far as we know yautja lungs are basically the same as human lungs, with only one difference. Yautja lungs are more efficient in taking up oxygen because their lungs have more blood vessels and have a bigger lung capacity.
Yautja skin is reptilian in origin, although at first they appear to have no scales. Over millions of years the scales on them have become so fine they are now nearly invisible.The skin is also extremely tough and can withstand temperatures of up to 250°C without being burnt. Although when faced with cold, even say, 10C, Yautja will die in a matter of hours. It also gives good protection against small caliber weapons (9mm) like a bullet proof vest.
The skin color has many variations. Ranging from brown redish colors right through to bluish-greenish colors. This large variety of colors and patterns probably came about when the yautja started to settle on other planets. Presumably their ships where not as fast then as they are now and it would have taken some time just to get to an other solar system. Yautja on other planet would have been almost cut of from the rest of their species. These yautja would then start to adapt to this new environment producing this great variaty of colors and patterns.
Unlike humans, who reproduce the whole year round, the yautja seem to have a mating season. This makes sense since males and females live separately most of the time and males are often light-years away from home, hunting on other planets.
Interestingly, the yautja mating season does not seem to be written in stone, as both males and females are capable of reproducing outside the mating season. Normally creatures who have a mating season can only reproduce during the mating season. Yautja it seems can reproduce the whole year round but don't.
There are two theories as to why this behavior exists:
1. Mating season is part of their culture and is sustained for religious reasons or for the sake of tradition.
2. Mating season is simply convenient because of the earlier mentioned distances between males and females.
Mating season is a 30 day period which occurs roughly every 400 days. During the mating season the males try to mate with as much females as they can. The high ranking males will attract enough females just because of their status. The males that are lower in rank will have to fight for their females. This behavior is probably millions of years old. It dates back to a time that the first yautjaoids where beginning to evolve. It is likely that the flat crests on top of a yautja's head developed for the purpose of attracting a mate. During mating season a successful male can mate with up to 20 females. This only happens to really successful males these are real top hunters. For the overall population 2 or 3 females is really a lot. But because of this type of distribution of females a lot of males are left without females. This is also the reason most males don't mate for the first time until they are at least 50 to 60 years old and have acquired a reasonable trophy collection. Some times it doesn't happen at all, for instance: when a male is seen as unfit for breeding and he is castrated, or when the yautja becomes one of the eta because of dishonor or cowards. Sometimes the lowest hunting males are also unable to acquire a female these frustrated males may turn on their subordinates.
The yautja male reproduction system is similar to that of a human male. On the other hand, the female reproduction system differs quite a lot from that of humans. Although the outside appearance of the female reproductive organs is similar to that of a human, the inner workings are quite different. Although yautja give live birth the babies develop in an egg like structure. A similar type of reproduction implied by some snakes which hatch there eggs inside their bodies. This type of reproduction is called ovoviviparous (Ovoviviparous having non-shelled eggs which hatch internally of the female).
In yautja this type of reproduction has evolved it self into something much more specialized then just the hatching of an egg inside the body.
On the ovary only one egg at a time ripens. It takes 40 days and the egg will be ready to be fertilized for the next 70 days. Although the egg is ripe and ready to be fertilized it is not yet fully grown, It will only grow to its full size when it its fertilized. The egg is fertilized whilst still on the ovary which will allow it to develop further. When the egg is fertilized, the yolk, which will have to support the growing yautja fetus, starts to grow in mass. The next 80 days will be crucial. In this period of time the yolk grows to its full size and the fertilized egg starts to develop into a fetus. Meanwhile, the walls of the "womb" start to produce a thick coating of moist holding slime and blood vessels. This coating will later on provide the growing fetus with oxygen, fluids and a means of removing the carbon dioxide and other waste products. Before this time the egg gets it's oxygen and water from the albumen. After the first 80 days the egg has grown to its full size and detaches itself from the ovary. The womb coating will cover it completely within days. The fertilized egg has now become an embryo and the basic shape of the yautja has revealed itself. The embryo is attached to the yolk by an umbilical cord; It will get its food from here for the next months. From now on the embryo will keep growing until it has become a baby ready to be born.
Nearing birth the yolk has shrunk to the size of a Ping-Pong ball, although it isn't round. In the next few hours the yolk will merge with the embryo's abdomen. When the child is born the yolk can still be seen as a small elongated bump on the stomach with a slightly different color as the rest of the body.
This type of reproduction has definite advantages over actually laying eggs. The eggs can grow much larger because they don't need a hard shell. The yolk can grow much larger because the amount of albumen needed is reduced immensely. The womb coating provides the oxygen and water that used to be provided by the albumen.
The yautja society is made up of different classifications, including blooded and un-blooded. Their caste includes:
(All these figures are estimates)
Unblooded - About 35% of male yautja are unblooded.
Blooded - About 25% of male yautja are blooded.
Retirees - About 25% of male yautja are retirees, yautja who have fought their time and now are too old and honoured to hunt. Females come under this section.
Adjudicators - The adjudicators are the admin and law yautja. These are often seen as 'not real yautja'. They include huntmasters and world leaders. About 13% of Yautja are adjudiucators.
Bad Bloods - These are the criminal yautja whom have been sentenced to death and escaped. Their justice system shows that crime is very low. About 2% of yautja are bad bloods. In Predator concrete jungle on the ps2 bad bloods were also predators captured by humans and brainwashed and met honorably deaths by there clan brother the main predator in the game
Male yautja hunt and in that case some people say they are predators. When a male yautja is ready for its first hunt it is a unblooded predator. When a unblooded predator completes a hunt it is marked and is now a young predator. A predator has better hunting gear the higher rank it is. When the predator proves itself worthy enough, the elder will present the predator The Combistick which, to their culture is a very rare item. Other rare items include stronger plasmacasters, the laser-guided smart disc, and Razor whip.