Corrosive - ?
Incendiary - Sets alight to the enemy.
Siphon - Attaches to enemies and siphons away health.
Radiation - Breaks shields and makes enemies more susceptible to damage.
Electrical - Which can stun your enemies or disable the HUD of other Ark Hunters.
Biological - Slows the movements of enemies by sticking a material to their feet
This is all I got from the wiki. What does the symbol look like for each one?