On the other hand, if I do want to fight this guy how hard will a giant shrimp be to kill? I've personnaly broken down it's descriptors like this:
It's wimpy. Not as wimpy as it could be, but of the specials it could have, it has the second-least dangerous.
1. A Gigantic one eyed shrimp ~ Very large, and there is only one eye to take out to blind the beast
FBs and titans are all always the same size, specifically 10,000,000, meaning they have twice the volume of an elephant. That is quite large, but that makes them only a little larger than most semimegas and less than half the size of a full-grown dragon.
I'm pretty sure all FBs have [EXTRAVISION], making them impossible to blind. The one eye just means it has one fewer body part to distract your attacks on its vitals, except dwarves virtually never attack eyes anyway. In short, it's cosmetic.
2. It has large mandibles... ~ I'm betting these are able remove various limbs with ease, or at the very least do heavy slicing damage.
It basically just has a slashing/piercing attack, which, while better at removing limbs than blunt attacks, still won't be very dangerous. A reasonably-skilled soldier will basically dodge or block all of its attacks anyway, though they'll probably get bowled over from constant charges.
3. ...it undulates rhythmically ~ Only a descriptor
4. Its green exoskeleton is wrinkled ~ Heavily armored? Or very poorly armored if chintin's protective ability has been nerfed like I think it has.
Both of these are purely cosmetic.
5. Beware its poisonous sting! ~ Obviously poisonous, most likely some sort of nerve toxin. (even if it's not I will treat it as if it is until I learn otherwise) Meaning any dorf getting stung is a dead dorf walking.
This just means that it has to successfully sting a creature to deliver its syndrome. The syndrome a FB causes is random; it might be nearly-instantly fatal, it might be a nerve toxin that's gradual death... Or it might cause temporary fever and nothing else. Both are equally likely. And since it has to successfully sting to cause its syndrome, not only is it less likely to attack with its syndrome-causer than other FBs would, it can be blocked, parried, or dodged by a skilled soldier. Whats more, AFAIK it won't use its stinger on a charge, and it's likely to spend most of its time charging. As such, this is the least-dangerous form of syndrome-causing special and the second-least-dangerous special in total (after only "Beware its webs!" which does absolutely nothing).
Regarding the poison, if it's delivered by a sting then does that mean there may still be a poison splater that my get spread? And would it work on contact or only on open wounds?
No spatter, no spread. This is another reason why poisonous stings are relatively benign.
FYI, the danger level of specials a FB can have go roughly in this order from least dangerous to most:
Beware its webs!
Beware its poisonous sting!
Beware its poisonous bite!
Beware its fire!
Beware its deadly spittle!
Beware its deadly blood!
Beware its poisonous vapors!
Beware its noxious secretions!
Beware its deadly dust!
...Pretty sure that's all of them. Webs does nothing (it doesn't even make the FB leave webs), sting and bite are attack-based and thus avoidable, fire can cause fires but is blockable, deadly spittle is an attack too but is usable at range, deadly blood leaves toxic puddles around, poisonous vapors are virtually impossible to avoid in melee, noxious secretions leave toxic puddles but can also affect creatures who grapple with or otherwise touch it, and deadly dust is virtually impossible to avoid in melee, smashes creatures against walls or off cliffs (sometimes fatally) like cave-ins do, and can leave toxic puddles.
Of course, all but webs and fire vary drastically in danger level depending on what the attached syndrome actually does. Sometimes you'll get a FB that's just horrendous, like one with vapors that cause all of the blood in a creature to suddenly vanish shortly after encountering the Beast, or one that's mostly harmless, like one whose sting causes short-lived nausea and nothing else.