First observation of mating behavior in three species of pelagic myliobatiform rays in the wild

Abstract

Information on elasmobranch mating behavior is limited. For batoids, observations of mating behavior in the wild are available only for a few species. We present video documentation of new cases of mating behavior for three species of myliobatiform rays. On July 20, 2013, a group of six cownose rays (Rhinoptera bonasus) were observed mating in shallow coastal waters off New Jersey. On August 19, 2014, two whitespotted eagle rays (Aetobatus narinari) were observed mating in Harrington Sound, Bermuda. In both cases, all stages of the mating sequence described in the literature were observed: 1) close following, 2) pre-copulatory biting, 3) copulation/insertion, 4) resting, and 5) separation. This is consistent with observations of mating behavior for whitespotted eagle rays and Javanese cownose rays (Rhinoptera javanica) in captivity. This is the first time a complete mating sequence has been documented in the wild for either species. Additionally, on May 18, 2015, a group of four bentfin devil rays (Mobula thurstoni) were observed engaging in pre-mating behaviors at the Archipelago of Saint Peter and Saint Paul, Brazil and is the first documented account of mating behavior for this species. In all three cases, we noted that the female was considerably darker in color than the males, which may be evidence of a visual pre-copulation cue, as seen in other marine fishes. The similarity of the behaviors presented here and those observed in other species (e.g., M. birostris, Hypanus americanus, and Taeniurops meyeni) suggests mating behavior may be highly conserved among batoids.