Siren

Sirens, also sometimes referred to as space sirens or space mermaids, are a species of fish indigenous to the etherium, and are known for luring and preying on unlucky sailors.

Physical
At a first glance, Sirens appear as large, elongated fish with the ability to swim through the etherium. However what sets a Siren apart is that their "tongue" is shaped like the upper half of an attractive, young, female humanoid being. This "lure" is capable of both folding itself inside its larger mouth, as well as sticking out to take on a more traditional "mermaid" appearance. Although referred to as the "lure", the humanoid half is, for all intents and purposes, a second body with its own mouth, lungs, eyes, and ears (if applicable), is capable of speech, and is where the Siren's brain is located. Despite this, the Siren still has a second set of external eyes and gill-like breathing organs. In addition, located on the sides of the Siren's body are retractable tentacles that can not only be used for grabbing prey, but also allow them to walk within gravity. Arguably the most surprising "feature" of the Siren is that the lure and parts of the main body take on the appearance of the father species, as Sirens are a solely female species and require an interspecies father. This allows Sirens to cater their attractiveness based on the species that live in the region. Regardless of the host species, all Sirens have razor-sharp teeth and retractable clawed fingers where applicable. As a solely carnivorous species (regardless of host), Sirens primarily prey on other sentient species. In addition to using their lure, Sirens are also capable of hypnotizing individuals with their gaze, as well as able to use their singing voices.

Human
Human-based Sirens are noted for having brightly-colored main bodies with large fins.

Calatian
Calatian-based Sirens, while thankfully lacking the Calatians' shapeshifting abilities, are covered in black scales, and have six tentacles instead of the usual four. In addition, their tail is tipped with a stinger.

Chondrichite
Chondrichite Sirens, compared to most humanoid Sirens, take on a structure more similar to sharks, in keeping with their host species.

Behavior
Sirens primarily prey upon merchant ships passing through their territory, however will sometimes prey on small military ships as well. As pack hunters, Sirens will usually keep their distance at first and size up their targets before swimming in. At this point, they will use their hypnosis and voices to lure in sailors. Once within range, they lash out aggressively and board in what can only be described as a bloodbath. In general, attacks are confined to the top decks, as Sirens will not pursue prey into confined spaces. Those killed in the attack are eaten, while the injured men are captured to be raped and eaten at a later time. Although these documented cases have more than painted Sirens as man-eating monsters, there have been recorded instances of Sirens approaching ships with more playful and curious intent. That being said, Sirens aren't beyond reasoning with other races, and have sometimes been paid to target specific ships as mercenaries/privateers.

Counter-tactics
The effectiveness of a Siren's song and gaze is determined by an individual's gender, sex, mental strength, and sexual orientation. While a heterosexual male will fall victim to a Siren easily, a heterosexual female is much more difficult to seduce. In addition, due to Sirens' reliance on blunt-force and slashing attacks, even the most simple of combat robots are able to effectively fight even large packs of Sirens. In combat, their weak points are, unsurprisingly, the inside of their mouth, as well as their walking tentacles, as well as their lure if applicable. In preventing attacks, military personnel have found that firing warning shots at circling Sirens is often enough to scare them off. While simply staying below deck is also an effective tactic, it does hinder the ship's operation, however it does mean ironclads almost completely immune to their attacks.