The diagram illustrates how small- and large-trapped species of the Venus flytrap deal with small prey in order to maximize the efficiency of digestive enzyme use.
Overall, both species initially respond in the same way: contact with trigger hairs causes the trap to close. However, their subsequent treatment of small prey differs markedly. Small traps proceed to digest the prey, whereas large traps reopen and release it, thereby conserving digestive enzymes for larger, more rewarding food sources.
In the case of small-trapped Venus flytraps, the process begins when a small insect touches the trigger hairs located on the inner surface of the trap. This mechanical stimulation activates the trap, causing the two lobes to snap shut around the prey. Once closure has occurred, digestive enzymes are released inside the sealed chamber. These enzymes break down the insect’s soft tissues, after which the plant absorbs the nutrients derived from digestion.
By contrast, large-trapped Venus flytraps react differently to prey of the same size. As with the smaller species, the insect first stimulates the trigger hairs and the trap closes. Nevertheless, because the prey is too small to justify the metabolic cost of digestion, no digestive enzymes are secreted. After a short period, the trap reopens, allowing the insect to escape.
In summary, while both species are capable of detecting and capturing small insects, only small traps digest them. Large traps avoid unnecessary energy expenditure by rejecting prey that offers limited nutritional benefit.