A morphological analysis of the ampullae of Lorenzini in selected skates (Pisces, Rajoidei)

Abstract

A comparison of the ampullae of Lorenzini among 40 species of skates (Rajoidei) demonstrates a close relationship between inferred electroreceptive capabilities and feeding mechanisms. Three general lines of morphological modifications are noted. (1) Whereas the majority of ampullary pores are located on the ventral surface of the dorsoventrally flattened body, the relative proportion of ventral pores is significantly lower on species inhabiting aphotic waters. (2) The ventral pores on more piscivorous species are distributed over a larger portion of body surface than they are on those species that feed primarily on invertebrates. Ventral pores in this latter group are more noticeably concentrated around the mouth and their densities on the adult are inversely related to the overall mobility of preferred prey species. (3) The size of each ampulla and the number of alveoli associated with it are directly related to the habitat depth occupied by each species. Shallow-water species have smaller ampullae with fewer alveoli than deeper-dwelling (> 1,000 m) species. The general distribution of ampullary pores on deep dwelling rajoids appears to compensate for reduced visual input, whereas their relative densities are a measure of the system's resolution and reflect major differences in feeding strategies. The increased ampullary size and complexity observed in deep-sea rajoids provides mechanisms to increase both the sensitivity and signal-to-noise ratios.

Olfactory morphology of carcharhinid and sphyrnid sharks: Does the cephalofoil confer a sensory advantage?

“…Some species may possess a greater density of chemosensory cells, which would increase the signal-to-noise ratio and provide greater sensitivity. This is directly analogous to the number of sensory hair cells in the ampullae of Lorenzini, with more cells providing a greater signal-to-noise ratio of bioelectric fields (Raschi, 1986).…”

Distribution of ampullary pores on three catshark species (Apristurus spp.) suggest a vertical-ambush predatory behaviour

“…The labial pores in A. microps may suggest some in-sediment feeding and would therefore suggest that the increased mean pore number on the dorsal surface is more for detection of predators than prey. The mean pore densities in all 3 target species (Table 1) match the relationship displayed by the mean pore number; density however provides a much better indication of electroreception resolution (Raschi 1986). Following this, both A. aphyodes and A. microps have greater electroreception resolution on the dorsal surface, whereas it is on the ventral surface that A. melano asper exhibits the greater electroreception resolution.…”

“…Pores were counted in situ by direct visual inspection with counted pores marked in ink to limit observer error. Pore density estimations were established following Raschi (1986), utilising ImageJ picture analysis software.…”

“…However, by far the most important use of electroreception in elasmobranchs is believed to be predator/prey detection (Kalmijn 1971, Raschi et al 2001. The distribution of ampullary pores in elasmobranchs has been studied in numerous species (Fishelson & Baranes 1998, Kajiura 2001, Atkinson & Battaro 2006, and there is an increasing interest in mapping ampullary pore distribution as a tool to infer behaviour and eco logy (Fishelson & Baranes 1998, Kajiura 2001, Atkinson & Bottaro 2006, Kempster & Collin 2011a.…”

Electrosensory pore distribution and feeding in the basking shark Cetorhinus maximus (Lamniformes: Cetorhinidae)

“…The electrosensory system of sharks is comprised of a series of electroreceptors, known as the ampullae of Lorenzini, distributed over almost the entire surface of the head anterior to the first gill slit. The major role of the ampullae of Lorenzini is thought to be for the detection of prey (Kalmijn 1971, Raschi et al 2001, Kajiura et al 2010. However, other functions have been suggested, including the detection of predators, the facilitation of social behaviours (Sisneros et al 1998) and the ability to orientate to and navigate within the earth's magnetic field (Kalmijn 1974(Kalmijn , 1978(Kalmijn , 1982.…”