Fig. 4. (A) An image of a colony before anesthetization. (B) The same colony after anesthetization with MgCl₂. Single arrows indicate a lophophore that has turned around after anesthetization; chimney height (H) is the difference in height between the tallest part of the chimney and the shortest part of the canopy (double arrows). These images were taken in side view with the light sheet perpendicular to the colony. (C) Scatter plot of chimney height before and after anesthetization (N=6). (D) Scatter plot of the change in chimney height after replacing seawater with anesthetic (0.35 mol l^–1 MgCl₂).