Anatomy and motor pathways of the electric organ of skates

Abstract

The electric organ of skates is a paired structure within the tail consisting of two longitudinal columns of electrocytes contained within the lateral musculature on each side of the vertebral column. The electrocytes develop from hypaxial skeletal muscle fibers, and, depending upon the species, are generally classified as either cup-shaped or disc-shaped. The disc-shaped electrocytes are considered to be the more derived type. Regardless of the morphology of the electrocyte, the electric organ discharge of all skates is characterized as a weak asynchronous and long-lasting signal. Although recent behavioral investigations have revealed a communicative function for the electric organ, details as to which specific behaviors utilize this motor system remain uncertain. The electric organ is innervated by segmental motor nerves that branch from the ventral root of caudal spinal nerves at all levels of the electric organ. The cells of origin of the electromotor nerves, or electromotoneurons (EMNs), are large multipolar neurons with extensive dendrites located within the ventral gray matter of the spinal cord. The EMNs are uniformly distributed among the somatic motoneurons at levels corresponding to the rostrocaudal extent of the electric organ, and therefore do not form a discrete nucleus. The medullary command nucleus is comprised of neurons located within the nucleus raphe magnus, and forms a descending spinal pathway to the EMNs. Anat Rec Part A 273A: 648 -662, 2003.

A new Miocene skate from the Central Paratethys (Upper Austria): the first unambiguous skeletal record for the Rajiformes (Chondrichthyes: Batomorphii)

“…Compagno 1977; McEachran & Miyake 1990a; Herman et al. 1996; McEachran & Dunn 1998; Koester 2003; Aschliman et al. 2012a).…”

Morphological variation in the electric organ of the little skate (Leucoraja erinacea) and its possible role in communication during courtship

“…Sexually dimorphic organs result in sexually dimorphic EODs in other weakly electric fishes (Hopkins et al 1990). As Koester (2003) suggests, perhaps the lack of evidence for sexually dimorphic skate EODs is due to the paucity of attention they have received and not necessarily because differences do not exist. Ewart (1888) and Lyons (1990) found that large increases in organ weight to small increments of overall skate growth occurred around the onset of maturity.…”

Morphological Traits and Capture Depth of the Norwegian Skate (Dipturus nidarosiensis (Storm, 1881)) from Two Mediterranean Populations

“…Therefore, taking into account on one hand, that fish morphological characteristics can show high plasticity in response to different environmental conditions [78], and on the other that it is well known that skates generally show low dispersal ability [79,80], the presence of two morphologically distinct populations of Norwegian skate in the Mediterranean basin seems to constitute a robust hypothesis. Moreover, this morphological differentiation could be evidence that the presence of D. nidarosiensis in the Mediterranean is not relatively recent [13], indeed the environmental selection had the time [77,81] to produce two morphologically distinct populations.…”