FIGURE 1. Radiographs in left lateral view depicting the extreme positions of the pharyngeal jaws in Muraena retifera (Familia Muraenidae - Ordo Anguilliformes - Classis Actinopterygii) during prey transport.
a, Posterior placement of the pharyngeal jaws in relation to the skull. The arrow points to the pharyngeal jaws. b, Pharyngeal jaws in their protracted position. The arrow points to the upper pharyngobranchial. Scale bar for a and b, 1 cm.
FIGURE 2. The oral gape cycle in relation to the pharyngeal jaw cycle in Muraena retifera (Familia Muraenidae - Ordo Anguilliformes - Classis Actinopterygii).
After peak oral gape (blue trace), oral jaws make contact with the prey (pink rectangle) by biting. Pharyngeal jaws (red trace) are fully protracted and the recurved teeth on the upper pharyngeal teeth are in contact with the prey. Pharyngeal jaws grip prey and begin retracting prey towards the oesophagus. Prey is pulled into the oesophagus as the moray extends its neurocranium forward and advances its body over the prey while increasing its oral gape, similar to a snake.
FIGURE 3. Detailed anatomy of the pharyngeal jaw apparatus in Muraena retifera (Familia Muraenidae - Ordo Anguilliformes - Classis Actinopterygii).
a, Left lateral view of a cleared and alizarin red-stained pharyngeal jaw apparatus, illustrating the sharp, recurved teeth on the pharyngobranchials used to grasp prey. Scale bar, 1 cm. b, Left anterior upper pharyngobranchial revealing highly recurved teeth. Scale bar, 500 micron.
FIGURE 4. Functional morphological model of pharyngeal jaw movement in Muraena retifera (Familia Muraenidae - Ordo Anguilliformes - Classis Actinopterygii).
The left dentary has been removed in a–c, and the left maxilla has been removed in b and c. a, Pharyngeal jaw apparatus at rest. b, Pharyngeal jaw protracted: the levator internus (LI) and levator externus (LE) protract the upper jaw into the oral cavity, whereas the rectus communis (RC) protracts the lower jaw. During protraction, the upper pharyngobranchial is dorsally rotated by contraction of the LI and the obliqus dorsalis (OD). c, After prey contact, the adductor (AD) contracts to bring the upper and lower jaws together to deliver a second bite. The dorsal retractor (DR) and pharyngocleitheralis (PHC) retract the pharyngeal jaws back to their resting position behind the skull. Scale bar, 1 cm.