When prey becomes killer: does a double lethal attack on a blue shark reveal a precise defensive strategy in young swordfish?

Published on
12. August 2020

When prey becomes killer: does a double lethal attack on a blue shark reveal a precise defensive strategy in young swordfish?

Teresa Romeo, Pietro Battaglia, Domenico Macaluso, Giuseppe Tagliavia, Teresa Manuela Vicchio, Manuela Falautano, Fabrizio Serena, Franco Andaloro

ABSTRACT:

In this paper a rare case of a double swordfish mortal attack against an adult blue shark (Prionace glauca) is reported. A female blue shark, with a total length of 3 m, was found stranded along the southern Sicilian coast (Strait of Sicily, Mediterranean Sea) on 30 May 2018. The analysis of this carcass revealed the presence of two swordfish bill fragments, impaled in the shark head; the former on the snout, the latter near the eye. The results of anatomical and computed tomography scanning analysis on the head of the blue shark showed that the larger bill fragment (19.7 cm) probably determined the death of this animal, having been impaled in a vital point, just behind the right eye. The analysis of both these events and other similar swordfish-shark interactions reported in the literature makes possible the hypothesis that young swordfish specimens put in place a precise defensive strategy against their potential predators or competitors, aimed at hitting vulnerable and vital points and delivering a mortal blow.

Journal of the Marine Biological Association of the United Kingdom, DOI: 10.1017/S0025315420000661

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