10.5061/DRYAD.4NJ8N
Hodin, Jason
University of Washington
Lutek, Keegan
University of Guelph
Heyland, Andreas
University of Florida
Data from: A newly identified left–right asymmetry in larval sea urchins
Dryad
dataset
2016
Dendraster excentricus
feeding
2016-08-02T22:55:48Z
2016-08-02T22:55:48Z
en
https://doi.org/10.1098/rsos.160139
68376 bytes
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CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Directional asymmetry (DA) in body form is a widespread phenomenon in
animals and plants alike, and a functional understanding of such
asymmetries can offer insights into the ways in which ecology and
development interface to drive evolution. Echinoids (sea urchins, sand
dollars and their kin) with planktotrophic development have a bilaterally
symmetrical feeding pluteus larva that undergoes a dramatic metamorphosis
into a pentameral juvenile that enters the benthos at settlement. The
earliest stage of this transformation involves a DA: a left-side
invagination in mid-stage larvae leads to the formation of the oral field
of the juvenile via a directionally asymmetric structure called the
echinus rudiment. Here, we show for the first time in two echinoid species
that there is a corresponding DA in the overall shape of the larva:
late-stage plutei have consistently shorter arms specifically on the
rudiment (left) side. We then demonstrate a mechanistic connection between
the rudiment and arm length asymmetries by examining rare, anomalous
purple urchin larvae that have rudiments on both the left and the right
side. Our data suggest that this asymmetry is probably a broadly shared
feature characterizing ontogeny in the class Echinoidea. We propose
several functional hypotheses—including developmental constraints and
water column stability—to account for this newly identified asymmetry.
Data_041916S. purpuratus asymmetry data (including all feeding
data)Dendraster_Data042816Dendraster asymmetry
dataDoubleRudiment_Data_FinalS. purpuratus double rudiment data