 Portias ' venom is unusually powerful against spiders . : 491 When a Portia stabs a small to medium spider ( up to the Portia ′ s weight : 428 ) , including another Portia , the prey usually runs away for about 100 to 200 millimetres , enters convulsions , becomes paralysed after 10 to 30 seconds , and continues convulsing for 10 seconds to 4 minutes . Portia slowly approaches the prey and takes it . : 441 – 443 Portia usually needs to inflict up to 15 stabbings to completely immobilise a larger spider ( 1 @.@ 5 to 2 times to the Portia ′ s weight : 428 ) , and then Portia may wait about 20 to 200 millimetres away for 15 to 30 minutes from seizing the prey . : 441 – 443 Insects are usually not immobilised so quickly but continue to struggle , sometimes for several minutes . If Portia cannot make further contact , all types of prey usually recover , making sluggish movements several minutes after the stabbing but often starting normal movement only after an hour . : 441 – 443 
