The table you provided contains information about the average mass, size, and regrowth time of different beetle species. However, it is not clear what the organic substance is that the beetle’s exoskeleton is made from.
Based on the information provided in the table, we can calculate the length of the Rhino beetle’s exoskeleton that will regrow per hour as follows:
Average size of Rhino beetle / Average regrowth time of Rhino beetle = 4.5 cm / 71 hours = 0.06 cm/hour
Regarding your questions about the Goliath beetle, it is known to be one of the heaviest and strongest beetles in the world, reaching more than 10 cm long. However, I couldn’t find any specific information on why their growth is limited to this size.
As for why growth periods are dangerous times for animals with exoskeletons, it has to do with the process of molting. Since the exoskeleton is hard and its outer layer is non-living, it cannot grow bigger by small increments as the human skeleton does. Instead, arthropods must go through the delicate process of shedding their old exoskeleton and expanding to a larger size before their new exoskeleton hardens. During this time, they are vulnerable to predators until their new exoskeleton hardens.