Question 10

Biologists investigated the directional movement of blowfly larvae (Lucilia sericata), which typically live in dark, damp microhabitats such as decaying organic matter to avoid desiccation and predators.

The biologists introduced a newly emerged larva, A, into the center of a circular testing arena. A single light source was positioned at one end of the arena. They recorded the path taken by the larva. They repeated the test with three more larvae: B, C, and D.

Figure 1 shows the biologists' results.

Experimental setup and results showing paths of blowfly larvae in a circular arena (Figure 1), alongside a dual-axis graph of larval chamber preferences and velocity across different temperatures (Figure 2).

Name the type of behavior shown by blowfly larvae A, B, C, and D, and suggest one biological advantage of this behavior.

At higher temperatures, blowfly larvae show an increased metabolic rate and faster locomotion, but excessive heat can cause cellular stress, immobilization, or mortality.

The biologists investigated larval movement at different temperatures using a choice chamber that was half illuminated (light) and half covered (dark). They released larvae at the midpoint of the central boundary separating the light and dark halves. They recorded the position of each larva after 10 minutes and calculated their mean velocity. This experiment was repeated with multiple larvae at several temperatures.

Figure 2 shows the biologists' results.

After analyzing these results, a student concluded:

there is a significant change in movement behavior between $∘C25\text{ }^\circ\text{C}$ and $∘C27.5\text{ }^\circ\text{C}$
between $∘C25\text{ }^\circ\text{C}$ and $∘C27.5\text{ }^\circ\text{C}$ , the larvae prefer to stay in the light
between $∘C25\text{ }^\circ\text{C}$ and $∘C27.5\text{ }^\circ\text{C}$ , the larvae crawl at a slower speed.

Suggest reasons why these conclusions might not be valid.