Xenochordata

**Xenochordata**, also known as **Skoulikiachordata** and commonly referred to as **Xenochordates** or simply **Chordates**, are a phylum under Animalisaliena and are distinguished by multiple features, the primary of which is a notochord. They are, on most continents, the dominant land animals, and comprise of about 11% of the total animal species on Hume III. Their evolutionary history has been traced to have begun roughly one billion years ago, and they share a distant ancestor with Xenoarthropoda. Apart from a notochord, these animals are also generally classified by possession of orbrachi at some point during development. This was most prevalent in early Xenochordates, as they used this to filter feed off of sea floors, though this trait began to either repurpose or deteriorate over time. The majority of land-dwelling Psariaskoulikion only possess these in early developmental stages, being present in the form of slight extensions off of the mouth. Others have evolved this trait into further uses for feeding, communicational appendages, or digestive organs, among many others.

## Anatomy

The notochord as identified in terms of Xenochordata is, though similar, not the same structure as in Chordata on Earth, and has simply been given the same name for convenience's sake. The notochord on Hume III generally consists of a long, rod-like structure composed of a number of different cells, usually a form of cartilage-like material. Depending on species, the length of the notochord relative to body size can vary widely, stretching at most from tail to the majority of the head to at least being a minor part of the skeletal structure or completely not present in adult form. Some species have evolved the notochord to function largely as a bone, especially primitive Xenochordates, which evolved the structure as a support to allow for larger body size and more complexity. The generally flexible nature of the notochord allows it to be implemented into various different body types with ease, and it has also led to use as an additional cell-producing organ.

As well as the notochord, the majority of Xenochordates possess orbrachi at some point during development. Orbrachi, deriving their name from Latin roots "brachi" (meaning "arms") and "or" (meaning "mouth" or "cavity"), are a type of cilia that extend from around the organism's mouth, ranging in length from microscopic to feet long depending on species. The first Xenochordates had either microscopic or nearly invisible orbrachi, which were used largely for filter-feeding, drawing small particles from the water towards their mouth. This led to them being largely prey in a rapidly-growing ecosystem, thus encouraging more diversification. In present times, orbrachi are used for a wide variety of applications, including retaining their original purpose, being used as additional sensory organs, being used as arm-like extensions to more actively capture prey, or, in the case of Psariaskoulikion and some others, being not present apart from in early developmental stages.

## Taxonomy

Subphyla, infraphyla, megaclasses, superclasses, and classes under Xenochordata:

Subphylum Psariaskoulikion

* Infraphylum Pseudopsariaskoulikion
	+ Class Pseudoskoulikionpsaria

* Infraphylum Eupsariaskoulikion
	+ Megaclass Epithymia
		- Superclass Chorissafiepithymia
		- Superclass Proboscia
		- Superclass Septempollicems
		- Superclass Cathibian
		- Superclass Karcharias
	+ Megaclass Entypia
		- Superclass Skoulikientypaonpsaria
		- Superclass Operajawedia
		- Class Proboscisentypia
	+ Megaclass Blinadospinapoda
		- Superclass Kokaloa
		- Superclass Chondroschondrosa
		- Superclass Cartilagooseoa
		- Superclass Chondrosa
		- Class Thorakismenoskoulikichondroua