Question 22N.2.HL.TZ0.g

Common shrews (Sorex araneus) are small mammals found in Northern Europe. Their diet includes insects, slugs, spiders, worms and amphibians. They do not hibernate in winter because their bodies are too small to store sufficient fat reserves.

[Source: [Shrew], n.d. [image online] Available at: https://www.pxfuel.com/en/free-photo-jslkw [Accessed 29 October 2021].]

To study brain size in shrews, researchers anesthetize them, X-ray their skulls and measure the height of the braincase (BCH) where the brain is located. The graph shows the relationship between BCH and the brain mass of individual adult shrews.

[Source: adapted from Lá zaro, J., Hertel, M., LaPoint, S., Wikelski, M., Stiehler, M. and Dechmann, D.K.N., 2018.
Journal of Experimental Biology 221. http://doi.org/10.1242/jeb.166595.]

The researchers found that the BCH of any individual adult shrew could vary seasonally. They collected shrews at different times of the year. The BCH of each shrew was compared with its body mass. The results are displayed in the chart.

[Source: adapted from Schaeffer, P.J., O’Mara, M.T., Breiholz, J., Keicher, L., Lázaro, J., Muturi, M.,
Dechmann, D.K.N., 2020. R. Soc. Open Sci. 7. http://dx.doi.org/10.1098/rsos.191989.]

Shrews were observed in different seasons and the time they spent on a particular activity was recorded and expressed as a percentage of the total observation time. The circles in the kite shapes represent the mean value of time for each activity.

[Source: adapted from Schaeffer, P.J., O’Mara, M.T., Breiholz, J., Keicher, L., Lázaro, J., Muturi, M.,
Dechmann, D.K.N., 2020. R. Soc. Open Sci. 7. http://dx.doi.org/10.1098/rsos.191989.]