Comparative osteological studies on skull structure and shape of some coral reef fishes adapted to different feeding habits

The present study aimed to compare the diversity of head skeletal structure and shape between some coral reef fishes with different feeding habits, by using the technology of radiography (x-ray). This study was conducted to clarify the osteological structure, size, and shape of skulls in three coral reef fishes (Acanthurus sohal, Novaculichthys taeniourus andFistularia commersonii). These three coral reef fishes were collected from Hurghada, Red Sea, Egypt in 2021. Skulls were separated, prepped, and radiographed with X-rays. The pictures were reviewed by 15 radiology specialists and registrars who used DR varex workstations to assess whether the bones were visible or not. Results showed that the morphology and anatomy of skulls in coral reef fishes have undergone variation in size, shape, and degree of skeletal mobility according to specialization for various modes of feeding. The skull of herbivorous fish, A. sohal is a triangle in shape. The width of the skull is larger than its length. It has a small mouth with short, stout jaws provided with very tiny smooth lobed incisor teeth. The skull of carnivorous fish, N. taeniourus is composed of multiple movable blocks of bones. The mouth is slightly larger with robust jaw bones; the jaw has 2 pairs of stout, canine teeth positioned anteriorly on the upper and lower jaws and there’s no canine in the hindmost region of the jaws. The head in planktivorous fish, F. commersonii consists of a long, tubular snout that constitutes almost one-third of the total body length. The snout ends in a small mouth; the lower jaw is slightly larger than the upper jaw with the absence of jaw teeth. The present study concluded that examination of the skull in some coral reef fishes with different feeding habits resulted in a significant diversification to evolutionary modifications of skull anatomy in fishes.