Tyranid genetics

In the fictional Warhammer 40,000 setting, the Tyranids are a nomadic alien race comprising many genetically engineered sub-species. They are sometimes known as the "Great Devourer" and are the "most alien race" ever encountered by the Imperium. They apparently exist solely to multiply their numbers, primarily by attacking, conquering, and consuming entire planets, before moving on to do the same once more in a more advanced and powerful form. All Tyranid 'technology' consists of engineered organisms or their by-products, from projectile weapons that fire ravenous larvae by means of muscle spasm, to their interstellar vessels, which are living organisms wholly adapted to living in vacuum.

Biology
The assimilated DNA structures and resources of the planets invaded warp Tyranids into a multitude of genera, all of which have an extremely rapid rate of evolution. Tyranid matter is constantly reabsorbed into biomass reclamation pools, called Digestion Pools, and terraforming devices, called Spore Chimneys, to create new varieties mixing with new assimilated DNA structures of the races of the invaded planet.

The digestion and absorption of a planet and its lifeforms by the Tyranids happens over three stages:
 * The first is marked by the spread of Spore Chimneys which spew genetic material across the planet. The genetic material enhances and speeds up the rate of reproduction of the indigenous plant life and quickly converts these lifeforms into Tyranid genetic structures that allow them to be easily digested.
 * The second is through the creation of Digestion Pools, which allow for a collection of genetic material on a planet by digesting the Tyranids into their genetic material.
 * The third stage is when Hiveships take the material and produce new evolutions and mutations of Tyranids. This material is sent to the Hiveships via Capillary Towers.

All of the material at the Hiveships are processed by Norn Queens, a biological factory type creature, whose job is to produce advance species and units to further aid in devouring future enemies.

Biomorphs
Because tyranids recycle DNA and are subject to rapid evolution, several genetic permutations can be found on every tyranid being. These "biomorphs" are treated as add-on abilities by the Warhammer 40k Rules.

Tyranids can be equipped with:
 * Acid Blood:The Alien blood spilt from certain Tyranid life forms is so corrosive that can eat through armour and dissolve flesh in mere moments.
 * Acid Maw: A prehensile tongue dripping with corrosive venom makes the Tyranid's attacks more dangerous.
 * Adrenal glands: A polyp-like parasite that pumps adrenal fluids into its host.
 * Bio-Plasma: The ability to organically generate and heat plasma to spit on the opponent.
 * Bonded exoskeleton: By having a more covering partial exoskeleton, large Tyranids make themselves more resistant to damage.
 * Enhanced senses: By enhancing their sensory apparatus, some Tyranids are able to become more accurate at shooting bio-weapons. This usually takes form as additional sets of eyes or antennae.
 * Extended carapace: Most Tyranid species are able to grow a more covering carapace for better protection.
 * Feeder tendrils: Some Tyranid vanguard organisms grow super-sensory tendrils that are used to identify their opponents.
 * Flesh Hooks: The tyranid has evolved hooks to quickly get up on vertical surfaces. These can also be launched in a suppressive fire to prevent enemies in cover from attacking first in an assault.
 * Implant attack: A poisonous spine or sting at the end of the tyranid's tail or tongue that makes wounds inflicted by the creature much more deadly.
 * Leaping: Additional muscle and sinew allows the tyranid to jump in order to quickly close with enemies.
 * Mace Tail: A large, heavy pointed club at the Carnifex's tail to smash down any opponents that get too close.
 * Regeneration: To survive hostilities, the tyranid has the ability to rebuild lost organs.
 * Reinforced Chitin: The Tyranid has thick, extra armour plating over its chitin layer, making it more resistant to damage.
 * Scuttlers: Some Tyranids are intelligent and stealthy, and able to creep nearer to enemies unharmed before the main assault.
 * Scythe Tail: In contrast to the Mace Tail, the Scythe Tail attacks much faster and more rapidly, however it is not as powerful as the Mace Tail.
 * Spore Cysts: Spore Cysts produce a Toxic Spore Mine from the chitinous plates on the host's back.
 * Spine Banks: The creature is able to launch a shower of diamond-hard spines while using other weaponry, or like flesh hooks in a suppressive fire to keep the enemies' heads down in an assault.
 * Symbiotic Rippers: Larger Tyranids such as Warriors and Tyrants are more difficult to outnumber in assault as they are always surrounded by Rippers.
 * Thornback: Many hard spikes and thorns on the creatures back makes it large and terrifying, and hard to approach.
 * Toxic Miasma: A larger tyranid may have vents on its back, from which it emits poisonous vapour that slows the enemy.
 * Toxin Sacs: A little parasite feeds on the tyranid and excretes a lethal poison over its bio-weapons, making its attacks much more dangerous.
 * Tusked: Adamantine-laced tusks sprout from the tyranid's head, allowing it to execute a devastating charge.
 * Winged: Lighter exoskeleton and wings to move at a higher speed.

Melee Weapons

 * Bone Sword: Shaped like a massive sword and with a hilt made from the hard skeleton of the organism. It radiates a psychic energy on the command of the user, which sends the wielder and all nearby Tyranids into a blood frenzy, in game terms allowing them to strike in close combat normally, even if they have already been incapacitated by faster opponents. Also when it hits something it delivers a psychic shock that can stun the nervous system for a short amount of time.


 * Crushing Claws: Massive claws used by large Tyranids to squeeze and smash their enemies. They can be used against many enemies at a time.


 * Lash Whip: A sentient whip-like symbiote with the Tyranid which allows it to lash and ensnare enemies in close combat.


 * Rending Claws: Diamond hard claws that allow the user to rend through armour and metal.


 * Scything Talons: Long, sickle-like claws that make the tyranid much more dangerous when fighting up close. The Hormagaunt species of tyranid makes extensive use of scything talons.

Ranged Weapons

 * Barbed Strangler, or Hamus Gulalaqueo: Is very similar to the venom cannon, but is different in the type of projectile used. The weapon is host to a plant that produces the ammunition for the weapon. The large seeds are heavy and impact causes germination, which results in an explosion of barbed tendrils that tear and pierce anything it can.


 * Deathspitter, or Excessus Conspuo: Is a complex bio-weapon that uses a young creature as its weapon. The creature is inside of a solid tube of bone and muscle, and a crustacean like creature is responsible for launching the other. The first creature is shot out of the device and explodes when it comes in contact with air, forming an acid-like substance that is able to eat through armour.


 * Devourer, or Peredo Uoro: Is a hive of smaller organisms that are similar to Rippers. A tube on the device works as a means to fire out those organisms which attempt to devour and dig into anything it is launched at. They are highly corrosive and try to eat anything that gets in their path.


 * Flame Spurter: Is a creature that turns its bile into a chemical that ignites when it contacts air. It is used primarily by Gargoyles.


 * Fleshborer, or Pulpa Terebro: Is similar to the devourer and a common weapon used by Tyranids. It houses beetles that are grown within the weapon and are eventually shot from the weapon and use their bile and teeth to eat anything it can come in contact with. They eventually die after they use up their energy trying to eat anything in their path.
 * Spikerifle: A termagaunt weapon that is a tube of muscle which fires a spike. The spike is thrown at the opponent by the muscles of the tube.


 * Spinefist, or Spinosus Manus: Is a device that attaches to the respiratory system of its host and uses air to fire its weapons. Like other weapons, it has a crustacean creature that forms the weapon part, sending its spikes out of the weapon when air is pushed through. They are able to fire multiple spines over a short period of time.


 * Strangleweb: The organism is spider-like and releases a web substance. The web tightens around whatever it captures. They were used to capture live prey to be used for genetic engineering and mutating of future species.


 * Venom Cannon, or Sanies Effundo: Is a large, muscular tube like weapon. The weapon uses acids and other toxic chemicals as its ammunition, firing these after squeezing them out at high velocity. These chemicals lack the penetrating powers of some of the other weapons, but is able to eat through flesh and certain armours.

Speculative Connections
According to the Tyranid Codex for Fourth Edition of Warhammer (40,000), there are many speculative connections between existing Tyranid strands of DNA. These connections are only between how Tyranids relate to each other. For speculations of how Tyranid DNA may have related to other species, see Genetic Origins below.


 * Von Ryan's Leaper: or Gauntii Ryanis, is speculated to be from the Hormagaunt species.
 * Tyrant Guard: or Tyrannicus Scutatus, is speculated to be a genetic combination between Space Marines and the Tyranid Warrior.
 * Harridan: is speculated to be a combination of the Gargoyle Species and the Winged Warrior variant of the Tyranid Warriors.
 * Ymgarl Stealer: is speculated to be a stranded strain of Genestealer
 * Catachan Devil: is speculated to be a stranded strain of the Ravener.
 * Trygon: is speculated to be from the Ravener strain.
 * Haruspex: is speculated to be from the Ravener strain.
 * Malefactor: is speculated to be from the Zoanthrope strain.
 * Exocrine: is speculated to be from the Ravener strain.
 * Hierodule: is speculated to be a combination of the Dominatrix strain and the Carnifex strain.
 * Hierophant: is speculated to be a combination of the Dominatrix strain and the Carnifex strain.

Genetic Origins
These connections are only between how Tyranids related to other species. These suggestions come from the Tyranid Codex for the Third Edition of Warhammer (40,000).

The following are current creatures and their speculated connections:
 * Tyrant Guard: rumoured to include Space Marine DNA, Tyrant Guard act as large, durable meatshields for the Hive Tyrant.
 * Genestealer: incorporating human DNA, they act as strong melee units
 * Zoanthrope: containing DNA incorporated from the Eldar, they act as the Tyranid's strongest psychic unit in Warhammer 40,000
 * Biovore: containing DNA incorporated from the Orks, they are one of the only Tyranid units that focus purely on ranged attacks in Warhammer 40,000 (the other being the Hive Guard).

The following are discontinued creatures and their speculated connections:
 * Squigs: Squigs were part of both Tyranid and Ork armies, bio-constructed from Ork genetic material. Tyranid squigs were later redesigned as 'Rippers'.