The cameraman photographs a variety of undersea life and records a dramatic battle between an octopus and a shark. The tentacles of a jellyfish and the flower-like sea anemone move rhythmically with the motion of the water. Barnacles, sea urchins, sea cucumber, starfish are engaged in seeking food, while a hermit crab inspects and finally crawls into a new shell abode. Animated diagrams are used to indicate the development of a fish; micro-photographs show us the maturation of a fish egg and the circulation of blood in a fish embryo. A shark and octopus engage in battle, the octopus discharging an inky fluid which serves him as a sort of smoke screen. The commentary is enlightening, but the vocabulary may be too difficult for younger children. The photography is excellent.
—review from EDUCATIONAL FILM CATALOG (1943)