Bocas del Toro Research Station - Smithsonian Tropical Research ...

EVA TOTH
Smithsonian Institution Postdoctoral Fellow
(2004), Smithsonian Marine Science Network
Postdoctoral Fellow (2005-2007)
Comparing the importance of colony relatedness
and environmental factors in the evolution of
eusociality in snapping shrimp
The fact that social insects such as ants, honeybees,
and termites give up their own chance to reproduce
in order to help rear the offspring of one or a few
individuals did not make much sense to Darwin,
who thought that individuals maximize their own
survival and reproduction. However, by helping
their relatives, truly social (eusocial) animals may
propagate their own genes indirectly.
Social shrimp live in the internal canals of sponges
and probably eat sponge tissue or detritus. Colony
size ranges from tens to hundreds of individuals,
depending on the species, colony age and sponge
size. One or a few large queens produce all of the
offspring from the colony. Once their eggs are
fertilized, queens carry them in their abdominal
pouch until they hatch. The rest of the colony
consists of juveniles of different sizes and larger
animals without developed gonads. Most are the
queen’s offspring. The larger animals defend the
sponge, and thus the colony, against intruders.
Because social shrimp were discovered fairly
recently and because they live underwater, they are
one of the least-studied groups of social animals.
Toth has been working to fill in the basic
information that will help us to understand how
these societies evolved. She has been developing
and using genetic tools to see how closely related
the animals are in each colony. She has also used
behavioral experiments to examine interactions
between colony members.
13
Eva Toth studies the little-known social systems
of snapping shrimp. To do so she snorkels or
uses scuba to collect entire sponges with their
resident colonies of shrimp.
Social Synalpheus shrimp (left) are tiny, from a few to 15 mm in length.
The queen, above, is carrying eggs (indicated) under her abdomen, the
green area that is missing in the worker, below. The shrimps live within the
walls of this Xestospongia rosariensis sponge (right).