''Hemisquilla'' is a genus of
mantis shrimp
Mantis shrimp are carnivorous marine crustaceans of the order Stomatopoda (). Stomatopods branched off from other members of the class Malacostraca around 400 million years ago, with more than 520 extant species of mantis shrimp known. All li ...
, and the only genus in the family Hemisquillidae.
It contains four species distributed in Australia and the Americas. Species in the genus typically eat snails, fish, rock oysters, and smaller crustaceans like crabs. They are preyed upon by larger bony fishes and cephalopods.
It is the most
basal living mantis shrimp lineage, and the
sister group
In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree.
Definition
The expression is most easily illustrated by a cladogram:
Taxon A and ...
to all other mantis shrimp.
Species
Four species are recognized:
Anatomy
Prey capture in ''Hemisquilla'' species is extremely rapid. Contact with the prey is made within 4-10 milliseconds, and the striking limb moves at a linear velocity of around 10 meters per second.
There are five physiologically different motor units composed of muscle fibers that work together to make this rapid strike possible.
References
Stomatopoda
Malacostraca genera
{{Stomatopod-stub