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Irken Biology

Internal Structure


Irkens have a skeletal structure not unlike those of humans.


Dib's X-Scope provides a good internal view of the Irken organs. The known Irken organs are the Squeedly Spooch, the heart, and the brain. 


The Squeedly Spooch is mainly located in the area where the human stomach is. From the X-Scope picture, it appears to be a large jumbled intestine-looking organ that stretches up through the rest of the body. Since it is so large, it may be a sort of super organ that does the combined duties of many human organs.


The smaller organ in the x-scope picture that can be seen poking up behind the Squeedly Spooch is most likely the Irken heart. The Irken heart serves the same purpose as the human heart, in that in pumps blood through the veins.


Irkens also have a brain, although without the Pak, the intelligence begins to drain. 


The Pak, which is almost an organ in itself, is attached to every Irken's spine. 


Irkens may have square cells, as Zim's computer shows.



Every Irken has a Pak, which is attached to their spines at birth. Paks are vital to the host's life; if the Pak is removed, the Irken's 10 minute lifeclock begins. Over the course of 10 minutes, the Irken's intelligence and life force begin to diminish until the Irken finally dies once the time is up. The separated Pak will latch onto a new host if given the chance. The Pak contains its host's Memory Drive (where the Irken's memories are stored), the Atmospheric Processor (which converts any atmosphere into a breathable substance), and the Charging Cell (probably the Irken's power supply). Their personality is also housed in the Pak, so if the Pak finds a new host, the old personality will begin to overpower them.


The occupation of each Irken is programmed into their Paks. Any change in jobs is done by re-encoding the Pak.


The Pak also has other helpful functions. Mechanical spider legs can extend from it to give the host a quicker and more agile means of transportation. The legs can also turn into laser cutters as well as a shield generator, or can emerge with a claw attachment. Other devices include a communicator, an ID plug of sorts (which Zim uses to try and purchase a snack on Devastis), an object transporter, space jets and a binocular helmet.

External Structure


Irkens resemble the typical little green man concept (green skin, antennae) with a more insectoid look to them. Their antennae are primarily used to express emotion, rising up and down depending on how that Irken feels. At the Great Assigning, the Irkens salute the Tallest by wiggling their antennae. Every other instance when an Irken has given a salute, they have done so with their hands in the same fashion as humans though. Although Irkens don't have any nostrils, they seem to smell from the same area as humans. Irken eyes come in three colors: Red, Purple, and Green (as well as different shades of these colors). Red eyes seem to be the most common and Green eyes are rare. Irken eyes have a shine that is lost when the Irken dies or becomes brutally retarded. Invaders have ocular implants, enhancing and strengthening their eyes. Whether or not average Irkens also have ocular implants is unknown. Irken tongues resemble red earthworms and can extend quite long. Irken teeth are all interconnected in rows to form one long tooth. Irkens also do not require sleep.

Irken females are rarer than males, though this might just be in the military. Irken females do have some physical differences, but no major biological differences. Male and female Irkens are devoid of sexual organs. It is most likely that the Irkens started out as a race that could reproduce sexually, but once the mass test-tube method was invented, they lost this ability overtime. See the Irken Society section for more speculation about that. Whatever the back story is, Irken females do have some minor differences, visible in their facial features. Females have eyelashes and curled antennae. 

Irkens don't grow much during their life, but they do grow. They start out as Smeets (Irken babies) and then grow towards their final height (this growth may or may not be separated into multiple spurts). The difference between the Tallest and the rest of the Irkens has something to do with their growth spurts. Young Tallest are the same size as the average developing Irken, but then they suddenly go through a massive lengthening that puts them at the forefront of the Irken Empire. This probably means that taller Irkens have growth spurts that continue on for a longer time than the rest of the race.

Irken diet seems to consist of snack foods and soda. Some Earth food and drink cause pain to Irkens. Water, and some products that consist mainly of water, sizzles on contact with Irken skin. Select foods, such as bologna, also burn Irkens or cause allergic reactions. This isn't a problem for the Irkens though, since Earth is so far away from them.