Question

The Caribbean spiny lobster lives in coastal waters. Lobsters receive chemical cues from the environment through chemical receptors that line their antennules. Certain conditions, like an abnormally high concentration of salt, can temporarily inactivate these receptors.

Scientists investigated how Caribbean lobsters respond to different cues in their environments. The scientists used an experimental tank filled with saltwater that had two cave-like shelters at either end. Additional saltwater was released into shelter X, while saltwater containing different chemical cues was released into shelter Y. Pumps directed the flow of water toward the center of the tank.


Image adapted from Ross and Behringer. 2019. Scientific Reports. Licensed under CC BY 4.0.

Individual lobsters were placed in the center of the tank for 5 minutes and then the mesh gates were removed. The amount of time the lobster spent inside each shelter was recorded for the next 30 minutes. The experiment was then conducted again using saltwater with an abnormally high salt concentration throughout the tank. The table below gives the average percent of time lobsters spent in each shelter in trials with different chemical cues and salt concentrations.

Chemical Cue Shelter Salt Concentration in Tank
Normal High
Water from the tank of a healthy lobster X 5% 30%
Y 90% 58%
Water from the tank of a diseased lobster X 72% 32%
Y 15% 48%
Water from the tank of a stone crab (predator of lobsters) X 55% 38%
Y 25% 48%
Data adapted from Ross and Behringer. 2019. Scientific Reports. Licensed under CC BY 4.0.

Which best describes one way that the scientists' findings support the argument that information lobsters receive through sensory receptors can cause immediate changes in behavior?
A.
by showing that lobsters avoid chemical cues from predators and diseased lobsters at both normal and high salt concentrations
B.
by showing that lobsters were more likely to avoid shelters with cues from diseased lobsters when the salt concentration was high, but not when it was normal
C.
by showing that lobsters do not avoid chemical cues from healthy lobsters at both normal and high salt concentrations
D.
by showing that lobsters were more likely to avoid shelters with cues from predators when the salt concentration was normal, but not when it was high

Answer 1

D

At normal salt concentrations lobsters avoided the predator cue (stone crab): they spent 55% in the control shelter X vs 25% in the predator-cue shelter Y. At high salt (which inactivates antennular receptors) that avoidance disappeared (38% X vs 48% Y). This shows sensory information can immediately change shelter-choice behavior.