The cranial musculature of the toadfish (Opsanus tau)

The highly specialized cranial musculature of the toadfish is characterized by the following features: 1 Absence of intermandibularis and branchiomandibularis muscles. 2 Presence of levator premaxillaris muscle. 3 Very large branchial chamber, the outer wall of which is formed by seven branchiostegal rays connected by a strong fascia provided with muscles (oblique levators and adductors). 4 Highly developed masticator muscles (adductor mandibularis and pterygoids). 5 The rectus abdominis, sternohyoid, and hyohyoid muscles are attached by a median aponeurosis to the hyoid and basibranchial elements and directly to the hypobranchial cartilages; this muscle complex depresses the buccal floor in opposition to the geniohyoid. 6 The pelvic fins are in the jugular position. 7 Two narrow muscles connect the cleithrum with the fourth ceratobranchial. 8 The cranial musculature is obviously adapted to a carnivorous habit and particularly for increasing respiratory capacity under asphyxial conditions.