Sperm
motility parameters and spermatozoa morphometric characterization in marine
species: a study of swimmer and sessile species
V.
Gallego, L. Pérez, J.F. Asturiano and M. Yoshida
Abstract
The biodiversity of marine
ecosystems is diverse and a high number of species coexist side by side.
However, despite the fact that most of these species share a common
fertilization strategy, a high variability in terms of the size, shape and
motion of spermatozoa can be found. In this study, we have analysed both the
sperm motion parameters and the spermatozoa morphometric features of two
swimmer (pufferfish and European eel) and two sessile (sea urchin and ascidian)
marine species.
The
most important difference in the sperm motion parameters was registered in the
swimming-time period. The sperm of the sessile species displayed notably higher
values than those of the swimmer species. In addition, the sperm motilities and
velocities of the swimmer species decreased sharply from the moment the sperm
was activated, whereas the sessile species were able to maintain their initial
values for a long time. These results are linked directly to the
species-specific lifestyles. While sessile organisms, who demonstrate limited
or no movement, need to have sperm with a capacity to swim for long distances in
order to find the oocytes, swimmer organisms can move towards the female and
release gametes near it, and therefore the spermatozoa does not need to be able to swim for such a long time period.
On
the other hand, sperm morphology is related to sperm motion parameters and in
this study an in depth morphometric analysis by CASA software of ascidian, sea
urchin and pufferfish spermatozoa has been carried out for the first time. A
huge variability in shapes, sizes, and structures were found using electron
microscopy in the studied species.
