Xindi-Aquatic
The Xindi-Aquatics were a non-humanoid race that evolved to live underwater. They were one of the six original species of Xindi, with whom they shared a common genetic ancestry.

Overview
Unlike the Reptilians and the Insectoids, the Aquatics were complicated and enigmatic and were known to over-analyze, taking an excruciatingly long period of time to come to decisions; they once took six days just to agree to attend a specific meeting of the Council. However, the Aquatics' prudence was at times what kept the Council from breaking apart, which is why Degra had them build the weapon. ()

They responded better to visual stimuli and were extremely suspicious of the spoken word. They admired boldness and confidence and treated hushed tones with suspicion.

In 2154, one of their representatives to the Xindi Council was Kiaphet Amman'sor, a member of the extremely wealthy Ibix Dynasty. She wielded considerable power within the Xindi hierarchy. ()

Physiology
The Aquatic females were larger and had rougher skin than the males who were more slim and had smoother skin. Females had a more humanoid-looking face, whereas male faces were rounder.

They had slit-like irises in their eyes and were capable of seeing far better underwater than humanoids were. Aquatics had three fingers on each forelimb, ending in short fingernail-like claws, with webbing in-between for easier swimming. Their skin was a greenish shade and had blotches of olive. Like all Xindi, they had a fold at the top of their cheekbone. They had tails for maneuverability and their hind limbs were fins.

Language
Xindi-Aquatic communication was highly complex and, since the Aquatics were underwater beings, they did not use their mouths. When using the past tense, they switched to SONAR. ()

Aquatics learned the Human language in 2154 in order to communicate with that species. ()

History
During the Great Diaspora in the 2030s, the different Xindi species engaged in a civil war that ended with the destruction of their homeworld. The Xindi-Aquatics, like all the Xindi, had to colonize other worlds in order to survive. Thanks to the Guardians, they were able to find habitable worlds. The Xindi were then taught to think of the Guardians as god-like beings.

In the 2140s, the Guardians warned the Xindi Council that, unless they destroyed Earth, the Humans there would destroy their future homeworld. The Aquatics were originally against the building of such a weapon; however, they changed their minds after the Guardians presented a visual record of their future world's destruction. They eventually agreed to create it and were assigned to build the Xindi weapon, because they were the most level-headed and efficient. The weapon was built underwater on Azati Prime. ()

In late 2153, they agreed to the launch of a miniature prototype weapon, which killed seven million people on Earth. This led to the Humans sending  into the Expanse to stop the weapon. Throughout the following year, the Council monitored their advancement, as the Reptilians and Insectoids suggested alternate ways of exterminating the Humans. At the Council meetings, the Aquatic councilors were often the more balanced and level-minded members, suggesting that they continue monitoring them instead of sending a fleet to destroy them right away. ()

In 2153, after finding the location of the weapon, Captain Jonathan Archer, of the Earth ship Enterprise, tried to use the Insectoid shuttle to get into the weapon and destroy it, but was captured before he could do so. While he was away, the Xindi-Reptilians and Insectoids opened fire on Enterprise, nearly destroying it. ()

Degra didn't trust Captain Archer, but couldn't let go of the possibility that he was telling the truth that the Guardians manipulated the Xindi. In early 2154, after the Xindi Council ordered the Reptilians to cease their attack on Enterprise, Degra had the Aquatics, the only ones he could trust, transport Archer back to Enterprise. After he briefly regained consciousness aboard their vessel, he was put in an escape pod and left adrift for Enterprise to find. ()

The Aquatics finally decided to help the Humans, when Enterprise promised to destroy the Sphere network. As a result, the Aquatics sent several of their ships with Enterprise, the Arboreals and the Primates, in their concerted effort to fight the Reptilians and the Insectoids.

Ultimately, most of their fleet was defeated when the Sphere-Builders triggered the spheres to create massive anomalies, which breached the hulls of the Aquatic ships, releasing water into space.

After the destruction of the Xindi weapon, an Aquatic cruiser towed the Enterprise back to Earth. ()

Technology

Although Xindi-Aquatics attended the meetings of the Xindi Council in a large , they also had ships of their own. The Xindi-Aquatic ships were the most powerful and largest of the Xindi races, but compared to Primate and Insectoid ships, they were among the slowest and least maneuverable. Aquatic starships had to have every compartment filled with water for its crew. However, there was at least one room that could be used to house a humanoid and filled with breathable air, and that had a window to water for Aquatics to talk with them. ()

The largest of their cruisers resembled huge Terran manta rays and were large enough to comfortably accommodate an  vessel in its aft cargo hold. They were extremely powerful in comparison to those of other Xindi, destroying several Reptilian and Insectoid ships with ease at the final battle against the Xindi weapon. It was only because of the immense anomaly field that they were disabled.

The Aquatics were the inventors of the biometric hologram, which was used to train Xindi surgeons. The Xindi Council chambers were also fit with biometric holograms, as they were used to project viewscreens and images of Human physiology for use in the creation of a bio-weapon, as attained by Rajiin. ()

Starship classes
 Xindi-Aquatic cruiser
 Xindi-Aquatic escape pod
 Xindi-Aquatic scout ship

Appendices

Appearances

Background information 
When Executive Producers Rick Berman and Brannon Braga were deciding on which species should comprise the Xindi, they found selecting aquatics to be an easy choice. According to Braga, this was "because – just thinking about Earth – you can imagine sea mammals possibly evolving to a higher intelligence." Furthermore, the executive producers decided that the Xindi-Aquatics, like the Xindi-Insectoids, would be computer-generated characters (the fact they were was noted in the final draft scripts of  and ). ()

Precisely how to depict the Aquatics at first represented a puzzle. Executive Story Editor André Bormanis offered, "That was one of those things that, you know, conceptually seemed like, 'Well, wait a minute. How are we gonna pull this off? You know, we're not gonna be able to see these guys very often because it's gonna be a very expensive effect.' But, you know, they found a way to [do] it." ( audio commentary, ENT Season 3 Blu-ray special features)

Instrumental to the design process was some conceptual artwork created by Visual Effects Producer Dan Curry. "I first did some sketches that looked like a cross between a mermaid and the 'Creature from the Black Lagoon," he observed. After receiving constructive feedback on these illustrations from Berman and Braga, Curry proceeded with the design, taking inspiration from wildlife. "I went back, looked at different sea creatures and was inspired by an aquatic reptile called a '." () Accounting for this inspiration, Curry noted, "I wanted something that had that kind of prehistoric look, but I made it mammalian rather than reptilian." (Star Trek: The Official Starships Collection, issue 65, p. 10) He continued, "Instead of having it be four-flippered – and knowing that our alien aquatics have a technological culture, which means they must have hands, opposable thumbs and manipulate machines – I took a mosasaurus body from the armpits down, changed the tail structure somewhat and the rear flukes, and gave it arms – but arms more like a whale fluke for swim and guidance, assuming propulsion would be primarily from its tail." () Explaining why the Aquatics had to look like they could operate technology, Curry elaborated, "Since it's a sentient species it was important to me that it looked intelligent. The other Xindi species had to be able to relate to it and respect it. If it didn't look wise it would be sushi!" (Star Trek: The Official Starships Collection, issue 65, p. 10)

After Curry made several changes to the Xindi-Aquatic body that differentiated it from that of a Mosasaurus, attention turned to the face of the Aquatic. "Then we gave it more of a Xindi face – more smooth in a way, partway between a whale and a reptile," Dan Curry pointed out. () The emphasis on creating the Aquatics as intelligent-looking creatures helped shape the design of their faces; Curry took inspiration from animals he regarded as having this quality, including whales, dolphins and elephants, the latter of which he had worked with while living in Thailand. Considering how elephants influenced the facial design of the Aquatics, Curry reckoned, "I think that led us to a kind of -like skin texture and the way the eyes are set." More specifically, the designers repositioned the Aquatics' eyes from being on the sides of the head, where many sea creatures' eyes are also set, to a forward-looking position. "Moving the eyes forward so it has stereoscopic vision helped with that sense of wisdom here and it also gives it a little bit more of an anthropomorphic quality." (Star Trek: The Official Starships Collection, issue 65, pp. 10-11)

Eventually, Dan Curry illustrated another concept drawing to show precisely what he planned. This was signed off by the executive producers without them requesting any further changes. From there, the concept was taken to CGI vendor Eden FX. (Star Trek: The Official Starships Collection, issue 65, p. 11)

The magazine Star Trek: The Official Starships Collection (issue 65, p. 11) credited modeler David Morton with the modeling of the Aquatics and animator Eric Hance with the computer-generated rigging that allowed the creatures to be animated. However, Doug Drexler's blog stated it was CGI Animator Sean Scott who modeled the Aquatics, with additional assistance from Morton.   credited Morton for texturing both genders of the species and Scott for animating the CGI model of the female Aquatics.

While texturing the Xindi-Aquatics, David Morton mainly looked at dinosaurs, but also took cues by studying the makeup for the Xindi-Reptilians. "We tried to keep a lot of the shadowing, the detail and the wrinkling around the eyes," stated Morton. Of the male Aquatic, he said, "I didn't want the male to look like a 'happy turtle,' but he didn't need to be too scary: I just wanted a sense of giving him some timeless age – and a bit of an orangutan look around the face, even though he's a lizard." () Dan Curry commented, "Dave's [...] [Aquatic] facial textures made a huge difference and gave it a feeling of intelligence. Using those textures, giving the skin the proper amount of crenellations and folds and the way the gills move. That was Dave's artistry." (Star Trek: The Official Starships Collection, issue 65, p. 11)

The producers concluded that the Aquatics should behave in a certain manner. Sean Scott explained, "They were very insistent that the Aquatics didn't 'act' so much as that they 'spoke and floated." () Dan Curry recollected, "We didn't want it to move like an excited guppy. We looked at research on tails and stuff but mostly I think I just went in and mimed how I wanted it to move!" (Star Trek: The Official Starships Collection, issue 65, p. 11)

Finding an effective means to portray the Aquatics talking turned out to be a challenge. "We had to have it where they would talk, but we didn't want a mouth that would open and close: we felt it would look silly underwater," recalled Dan Curry. "So [Supervising Producer] Peter Lauritson had the idea that we would make the gill area behind the cheeks expand and contract, as if somehow it could force water through membranes the way hadrosaurus would force air through their crests, or the way certain species of frog will use their throats to generate sound." ()

Inserting appearances of the Aquatics into episodes was hugely expensive. "I remember the discussions and the production meetings about how many seconds each shot [of the Aquatics] would be, [...] because, you know, [...] you paid for the computing time," Co-Executive Producer Chris Black recollected. "[It] was hundreds or thousands of dollars an hour for someone to sit at a computer and animate these things and you had to be really judicious about it." Nonetheless, there was a lot of reuse in the footage of the Aquatics. "They're like a GIF; they would just sit on a little loop and you would cut back at them," continued Black, "but even burning them in [replacing blue screen which had been used during production], I remember, cost money." ( audio commentary, ENT Season 3 Blu-ray special features)

Very little was used to substitute the Aquatics while filming proceeded. "They had, like, a big fish bowl where they told you what was in it," remembered Degra actor Randy Oglesby. "I don't think there was anything in it but you just learned that was your point of focus and you had something to look at and then you just imagine, you know, what somebody's saying the lines of, off-camera, and you're able to hear and focus on that." (In a Time of War, Part Three: Final Conflict, ENT Season 3 Blu-ray special features)

At one stage, Archer actor Scott Bakula expressed approval of the physical design engendered by the Aquatics, enthusing, "I do love the look of them." () The Aquatics (in common with the Insectoids) were also highly praised though considered to be "kinda weird" by Consulting Producer David A. Goodman and Director David Livingston, the latter of whom remarked, "I like the fish." ( audio commentary, ENT Season 3 Blu-ray special features) For Chris Black, seeing the Aquatics in their underwater habitat, such as in , always slightly reminded him of the Guild Navigators from Dune, which are likewise shown lurking in murky tanks. André Bormanis approved of the look of the Aquatics, admitting a "love" of their appearance and saying they look "great." Black concurred, "It does look great, and especially considering how far the technology has advanced since then." Bormanis agreed with this viewpoint. ( audio commentary, ENT Season 3 Blu-ray special features) Dan Curry regarded the Aquatics as having "beautiful facial textures." He went on to say, "The final version [of the Aquatics] is a tribute to those great animators." (Star Trek: The Official Starships Collection, issue 65, p. 11) Brannon Braga was likewise happy with the depictions of the Aquatics, stating, "I liked the way we used the Xindi-Aquatics." () Braga also once joked that, instead of having had the Xindi-Primates befriend the Enterprise crew, "it's kind of a shame" that the Starfleet officers "couldn't befriend the fish people." However, he then went on to say, "That would have been too expensive." ("The Xindi Saga Begins", ENT Season 3 DVD special features) Braga was also impressed with the Xindi-Aquatic cruiser. ()

Apocrypha
In the chronology set out by the Pocket Books' series of Enterprise novels, the Xindi-Aquatics were not the first aquatic species depicted as peacefully co-inhabiting a planet with another species and being encountered by the NX-class Enterprise. In the  By the Book (set in 2151), Enterprise encounters a water-faring alien race called the  that share a  with a species known as the .

The novelization of  refers to the lights being dimmed in the Xindi Council's inner sanctum, the room lit only by graphics from a cartographic presentation, as being "in deference to the aquatic members of the group." This suggests the Xindi-Aquatics had some sight difficulty, either in general or merely outwith their watery surroundings, or preference for darkness when viewing displays external to that environment.

In the same novelization, the Aquatics are referred to as having been the first, from an evolutionary perspective, of the Xindi to have gained intelligence. The book also states that their development as a relatively peaceable society was a result of not being land-based and that the Aquatics insisted on political representation "only when the land-based [Xindi] races began to despoil their waters." A later statement explains, "Aquatic politics were based on equality and consensus, a concept foreign to the land-based species."

The novelization also describes the Aquatics as rarely speaking and having "soft, translucent dorsal fins," which flowed "delicately above them" while they made rapid turns, and "pale, moon-shaped and -colored faces," beneath which were bubble-producing gills. There was, apparently, no clear physical distinction between the members of the species, with no way to tell the males apart from the females.

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