Morphology of Urohyal bone and its relationship with feeding habits and habitats of some species of the order Pleuronectiformes

The urohyal bone is a single median solid bone with an anterior tip generallyconnected to the ventral hypohyal and to the first basibranchial, and the posterior endattached to the pectoral girdle by means of muscles. The morphology of this bone isstudied in five species belong to four families of order Pleuronectiformes. The resultsshow variation in the morphology of urohyal bone among the studied species, whichincludes the presence or absence of groove in dorsal and ventral parts, the presenceor absence of superior and inferior process in anterior part, and some other traits. InPseudorhombus elevates (Paralichthydae), the ventral part of the bone is completelycurved and U shaped so that the anterior and posterior ends lie in front of each otherand the dorsal keel is grooved. Ventral part in Euryglossa orientalis (Brachirusorientalis), (Soleidae), is U-shaped but the anterior and posterior ends do not lie infront of each other. In Psettodes erumi (Psettodidae), the bone does not have aprocess, its ventral part is grooved and the dorsal keel is along with the ventral part.In Cynoglossius arel (Cynoglossidae), the bone has a superior process, the dorsal keelis grooved and steeped, and the ventral keel does not have a groove and is curved.The observed morphological variation in the urohyal bone along with themodification of internal and external structures in these fishes indicate a probablerole of this bone in their movement and feeding behavior.

کلیدواژه ها:

Urohyal ، Pleuronectiformes ، Morphology