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Q37 - Why Bats Collide With Smooth Surfaces

Theoretical A Real exam question - full text reproduced under IBO's CC BY-NC-SA 4.0 license
Animal Communication

Ethology

Twenty-eight rare and protected species of bat live in Hungary. Bats sense their environments using echolocation, which is disrupted by different surfaces. A smooth metal plate was attached to the wall as shown below. Bats were recorded attempting to drink from, or colliding with, the floor, walls, or the plate on the wall.

Diagram of an experimental corridor corner: a smooth grey metal plate mounted vertically on one wall (dimensions 2m × 1.2m, positioned 1.2m from the floor), with a bat approaching, and high-speed cameras (marked “L1”) positioned to record collisions/drinking attempts at floor level. Fig.1. Legend 1 = High-speed cameras.

In a second experiment, the metal plate was instead placed on the floor, and bats were recorded attempting to drink from, or colliding with, the wall, floor, or the plate on the floor.

Two box-plot panels (Title 1: horizontally placed metal plate; Title 2: vertically placed metal plate) each with four categories on the x-axis (L1 = drink from ground, L2 = drink from plate, L3 = collision with wall, L4 = collision with plate) and y-axis = percentage of occurrence. Title 1 (horizontal plate): L1, L3, L4 all near zero; L2 (drink from plate) shows a large box spanning roughly 0-47% with a median around 22% and a long upper whisker to ~68% - bats frequently attempted to drink from the horizontal plate. Title 2 (vertical plate): L1, L2, L3 all near zero; L4 (collision with plate) shows a moderate box spanning roughly 6-20% with a median around 12% - bats frequently collided with the vertical plate instead. Fig.2. Percentage of drinking attempts and collision events in box plots. Values were calculated per individual relative to its total number of passes through the corridor. Title 1 = Horizontally placed metal plate. Title 2 = Vertically placed metal plate. Axis = Percentage of occurrence. L1 = drink from ground. L2 = drink from plate. L3 = collision with wall. L4 = collision with plate.

Why do bats react differently to smooth surfaces than to others? Indicate with an X if each of the following statements is true (T) or false (F).

Why do bats react differently to vertical and horizontal smooth surfaces? Indicate with an X if each of the following statements is true (T) or false (F).

Q37.1. The smooth metal plate/surface absorbs more sound than rough ones.
Q37.2. The smooth metal plate/surface only reflects sound back to the bat if the sound reaches the surface perpendicularly.
Q37.3. The vertical smooth metal plate/surface reflects sound in a way that attracts the bats.
Q37.4. The bat can only detect a small part of a smooth surface.
Q37.5. The sound reflected from a horizontal versus vertical smooth surface is different.
Q37.6. The bats' reaction is different because in nature bats usually only encounter horizontal smooth surfaces.
Q37.7. Bats use their sense of gravity to help them recognise water.
Q37.8. The bats collided with vertical smooth surfaces because they sensed it as open space.
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Question reproduced from IBO 2019, Theoretical Exam A, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Official answer key