Consideraciones ecomorfológicas del mecanismo de captura de presas en Xiphias gladius (Linnaeus, 1758)

Abstract

This paper analyzes the prey capture mechanism of the swordfish (Xiphias gladius), assuming a RAM feeding mechanism and a wide dietary trophic spectrum. The complete cephalic region is studied, and the osteology and miology associated with the prey capture mechanism are described. A four-bar linkage model was applied to assess the efficiency of the mouth opening and a biokinetic model to evaluate the mouth closure efficiency. The majority of the neurocranial structures are displaced towards the posterior region, with a high degree of ossification and a prevalence of joints with beveled edges and sutures. The vertical bar of the suspensorium, which supports the opercular series and lower jaw are noteworthy. The premaxilla and maxilla are closely jointed, without any possibility of relative movement, although a primordial ligament remains. The configuration of the lever system of the adductor mandibulae muscle determines the biokinetic system, whose force transmission efficiency is around 30% for the external fascicles (A2 + A3α) and 15% for the inner fascicle (A3β). The kinetic transmission coefficient (K = q · r-1) is 9.75, whereas the force transmission coefficient (f = r · q-1) is 0.102. The morphofunctional design that allows the capture of fast-swimming prey is analyzed and discussed; the high kinematic transmission coefficient coincides with the values found for piscivorous fishes.