tail spikes?

[Gshock]

what's the function of the tubercles..?? can they do harm to us if scratched??

sometimes i see fungus growing on them, espcially the newly acquired ones ... some in my friend's pond too ... probably due to poor water management ...

Denticles are used for aerodynamics in water, allowing for the ray to swim faster. Tubercles, being oversized modified denticles, i would presume have the same effect. It is quite hard so if you do get scratched, it will probably hurt, but theres no venomous sheath over it.

 

[Zoodiver]

what's the function of the tubercles..?? can they do harm to us if scratched??

The purpose is mostly defense. They are an added protective layer on the backs of rays. The only damage that could be done is purely trauma from a puncture. The tubercles (as posted) don't carry the venom like the tail spine does.