They lack a cell nucleus.
Take 68.2/60 = 1.137 hr
take 56.9/1.137 = 50.043 mi/hr
take 189/211 = 0.896
24.8/2 = 12.4 m
12.4/82.3 = 0.15s
In the diagram, the ship send sound(?) waves to the water, to determine if there is anything there. If there is something like a sunken ship shown in the diagram, the waves return in a shorter time hence you can understand if theres something or now. This is the principle of radars and sonars.
