A pair of entomologists at the University of Georgia has found that Joro spider heart rates fluctuate less when they are experiencing stress compared to similar spiders. In their study, published in the journal Physiological Entomology, Andrew Davis and Christina Vu captured specimens of several spider species and measured their heart rates while exposing them to a stressful situation in a laboratory setting.
Looks like about four beats q2s (Beats Per 2 Seconds BP2s); (60s/min /2s) yields 30 2s blocks/min * 4 BP2S = 120 BPM. I wouldn’t have guessed a spider’s heart rate would be 120; I think I expected something much lower.