Alright I have to step in again, one thing I need to say, two of you have knowledge in Xenobiology, however I think you both need to decide whether that is knowledge about alien zoology, or sapient biology. Some edits may be needed. It's mostly because I am finding your knowledge base to be too broad. Tbh the person best suited for dealing with alien fauna here is Ursea.
It's just somethin I think needs to be decided to prevent characters from being too knowledgeable. I give you each the option to chose one or the other.
Zeph's knowledge is entirely in "where to stab and how to kill something". The facts he listed about the first Kurg creature was just "How did you kill that thing with such a tough hide and armored heart, and how did you make sure that it's acid didn't spill everywhere and contaminate you?". If he had been asked about the creature's diet, it's breeding habits, it's environment, or anything beyond "I know this thing is filled with acid and has good armor" then he would not have been able to answer.
Zeph is
subjectively intelligent. He knows
very few important facts about quite a few things. Sapient species in the universe are
rare, so every university in the galaxy would be bringing them up during classes and lectures. There is not a single topic more fascinating in all of biology, nor a single topic more important to know when trying to kill something, than "How smart is this thing?"
That's why Zeph is
not a professional assassin trained in stealth discipline, nor is he a military trained fighter, nor can he work any of the scientific instruments that Rin's character can. He is not even close to the most knowledge person on the ship, because he's never actually attended a school. He is also the worst shot on the entire ship, because he's never had military training.
The man is deliberately underpowered, a liability to himself and his team mates, and dude who's picked up jack of all trades knowledge for the express purpose of either getting a sloppy kill and living to tell the tale, or to tell somebody else how to kill something. The only reason I could possibly think of for why Zeph the College Dropout could have gotten on this ship is because he
gets his jobs done with a unique skillset that is suited to one thing, and one thing only: Killing something that isn't looking, and running the gently-carress away.