A morphological novelty for feeding and sound production in the yellowtail clownfish

Abstract

The yellowtail clownfish Amphiprion clarkii is able to close its mouth very quickly by means of the cerato-mandibular (c-md) ligament, a synapomorphic trait of Pomacentridae joining the hyoid bar to the medial part of the lower jaw. This fast closure induces tooth collision, thus producing sounds that the clownfish uses during agonistic behaviors. To investigate whether this rapid jaw movement is also used during feeding, we analyzed the kinematics of sound production and feeding. Sound production, feeding on live planktonic prey, and feeding on food attached to tweezers was filmed with a high-speed camera. Three kinds of kinematic patterns were detected and were associated with the two different types of food presented: one performed to catch planktonic prey (PP), and two (called B-1 and B-2) to bite attached food items. The kinematic pattern of B-2 is similar to that observed during sound production (SP) and the transection of the c-md ligament highlights that sound production and biting-2 motions are dependent on this morphological trait. Our data show that the c-md ligament in addition to its role in sound production allows duplication of the mouth-closing mechanism during feeding. This highlights the key role played by the c-md ligament in sound production and feeding on attached prey. J. Exp. Zool. 323A: 227-238, 2015. © 2015 Wiley Periodicals, Inc.

Insight into biting diversity to capture benthic prey in damselfishes (Pomacentridae)

“…For all six species, we studied biting on food items fixed to tweezers (pieces of shrimp or mussel of roughly 1 cm long and 0.5 cm wide). The data for A. clarkii and S. rectifraenum come from our previous works (Olivier et al, 2015.…”

“…2c). High-speed video analyses revealed that the movements of the neurocranium and the hyoid apparatus are fast, which quickly tightens the ligament, ultimately allowing the fish to slam their mouth shut within 2-4 ms (Olivier et al, 2015Parmentier et al, 2007).…”

“…It was later illustrated that the same mechanism is also used during feeding (Olivier et al, 2015. There are three main trophic guilds in damselfishes: (1) the pelagic feeders that feed mainly on planktonic copepods, (2) the benthic feeders that mainly graze filamentous algae and (3) an intermediate group including species that forage for their prey in the pelagic and the benthic environments in variable proportions (e.g.…”

“…planktonic and benthic copepods, small vagile invertebrates and filamentous algae) (Frédérich et al, 2016(Frédérich et al, , 2009. A study on a zooplanktivorous species, Amphiprion clarkii (Bennett, 1830), showed that the c-md mechanism is never used to capture elusive prey (Olivier et al, 2015). However, A. clarkii performs two different kinematic patterns to seize fixed prey items, which are called biting-1 (B1) and biting-2 (B2).…”

“…Biting-1 does not look like the kinematic pattern for sound production and B1 is not dependent on the c-md ligament because the same kinematic pattern can be performed after its surgical transection; the fish uses the adductor mandibulae (AM) to close its mouth (Olivier et al, 2015). Conversely, B2 shows the same kinematic pattern as sound production and cannot be performed after the c-md ligament transection (Olivier et al, 2015). This study highlighted that the c-md mechanism is used in two different behaviours, i.e.…”