Commentary on Allee & Dickinson (1954), which found dominance hierarchies in sharks.

What is it about?

This is a commentary on the 1954 paper that claimed to have established dominance-subordination hierarchies in the Chondrichthyan evolutionary line. However, this conclusion was based on collision avoidance, not the series of agonistic actions by which these hierarchies are, by definition, formed. But collision avoidance is normal for sharks, given their morphological design, for they are subject to high impact on collision. This is especially true for small sharks, due to their small volume and lack of bony protection. As the length of a shark increases, its volume and mass increases by a function of its length cubed, so the experimental results are fully explainable by the basic instinct of self protection. Further, subsequent studies of the actual social behaviour of a variety of species of sharks and rays have not found size-dependent dominance subordination hierarchies. Complex interactions have been observed that may be based simply on personality differences.

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Photo by David Clode on Unsplash

Photo by David Clode on Unsplash

Why is it important?

Though no actual evidence that sharks form dominance subordination hierarchies has ever been presented, this paper has given generations of researchers the false impression that such hierarchies are necessarily present. Thus it has stood in the way of the true understanding of the very different societies actually found to be present among sharks.

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