A Daidal acanthocercus fossil. This is the holotype of the species. © Contributions to Zoology
Strictly speaking there is nothing known about the behaviour of Daidal acanthocercus.
The one thing we can infer from its anatomy, especially in analogy with modern mantis shrimp, is that it was probably a scavenger or ambush predator of relatively small prey that lived on the sea floor.
Its robust and spiny claws would be efficient tools for manipulating and shredding food items, which likely included some of the diverse invertebrates found at the same locality.