Female
stingray showing numerous fresh mating wounds along
the posterior margin of the body disc.
Dentition
from a male stingray in the mating season (top) and
the non-mating seaons (middle) and a female stingray
(bottom).
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Male elasmobranchs
bite and grip the body of their female mates during courtship
and copulation. In batoids (skates & rays),
this gripping action is facilitated by the development of sharp,
cuspidate dentition on the males only. Female dentition is generally
molariform but, despite the differences in tooth morphology,
the diets of the sexes remain the same.
Although the phenomenon
of dental sexual dimorphism has been previously documented,
it was only recently discovered that male
dentition changes shape on a seasonal basis. Only during the
mating season does the male dentition develop the cuspidate tooth
morphology; during the non-mating season the male dentition is
molariform, similar in shape to the female dentition which does
not change seasonally.
In conjunction with
studies of the tooth morphology, the resultant mating wounds
on female rays were quantified. Females have a
dermis that is 50% thicker than comparably sized males, presumably
to provide protection from the vigorous mating bites of the males.
The majority of bite wounds are located on the posterior half
of the body disc of the females. Some males also possess bite
wounds but they are much less common compared to the females.
The mating wounds closely follow the seasonal appearance of the
cuspidate male dentition. |
