Yet unless it's a small without sharp features bug, this defense form doesn't work at all.
Everything will either squish them, force open them, rip them open, claw them open, etc.
It's nearly as fruitless as Puff Up, but at least puff up can affect som smaller creatures if they are alone and always affects other yukkuris. . .
Maybe this method is great against other yukkuris? though dunno how, i bet the body slamming may be as bad as a human punching them in the cheecks and mouths still harming the babies inside.
Well i do believe that smaller bugs, may not be able to pierce through the mother, or at least being succesful in some degree being dying.
in numbers, that's another story, if a great group of ants can overwhelm a few yukkuris easily, i can bet a group of bettles and such, may have better chances.
The failure of the defense is against anything that can smack it or grope it hard, or against anything that can pierce it or slash it, so it really dependand of the capabilities and sizes of the agressor.
not many people know but this method actually works in some situtations, say if the yukkuri hers a loud noise and hides the children ahead of time, it increases the kos chance of survival by 30% in the case of human confrontation as long as the mother does not reviel the children inside them and the children remain quite. it also helps keep the children safe if there running away do to the kos slow pace it would allow the mother to move faster without the kos slowing her down.
People can tell when a mother put ko's inside them out of them looking inflated in a non puff way and them having a hard time speaking. Plus they only do it when the dangerous element is already infront of them seeing the whole thing, yukkuris never react properly when they hear weird sounds, they only go "what's that?" but they lack the preepmtive defensive instinct that many creatures have, It doesn't help that the protection wouldn't work because of their weak bodies and slow speed compared to bigger creatures than them.
The only way for this to work is for the yu to be let to run away, but that doesn't meant the child protection worked, it only means the yukkuri was lucky and found a human that wouldn't kill it, so having her childs insider her or not would be the same if the human would not kill them.
Besides, in the very end, what determinates if this works to some degree or not is the ammount of pictures showing it as succesful, and since child protection never worked to anything yu had faced in the stories where they do it, it leaves the whole child protection as pretty much useless to anything but, in theory, smaller creatures than adult yu's.