Gekko gecko as a model organism for understanding aspects of laryngeal vocal evolution.

The ability to communicate through vocalization plays a key role in the survival of animals across all vertebrate groups. Although avian reptiles have received much attention relating to their stunning sound repertoire, non-avian reptiles have been wrongfully assumed to have less elaborate vocalization types, and little is known about the biomechanics of sound production and their underlying neural pathways in this group. We investigated alarm calls of Gekko gecko using audio and cineradiographic recordings.

Comparative analysis of osteoderms across the lizard body.

Osteoderms (ODs) are mineralized tissue embedded within the skin and are particularly common in reptiles. They are generally thought to form a protective layer between the soft tissues of the animal and potential external threats, although other functions have been proposed. The aim of this study was to characterize OD variation across the lizard body.

The role of cranial osteoderms on the mechanics of the skull in scincid lizards.

Osteoderms (ODs) are calcified organs formed directly within the skin of most major extant tetrapod lineages. Lizards possibly show the greatest diversity in ODs morphology and distribution. ODs are commonly hypothesized to function as a defensive armor.

Biomechanical behaviour of lizard osteoderms and skin under external loading.

Many species of lizards are partially enveloped by a dermal armour made of ossified units called osteoderms. Lizard osteoderms demonstrate considerable species-specific variation in morphology and histology. Although a physical/protective role (against predators, prey, conspecifics and impact loading during falls) is frequently advanced, empirical data on the biomechanics of lizard osteoderms are scarce, limiting our understanding of form-function relationships.

Sound production and mechanism in the cryptic cusk-eel Parophidion vassali.

This study investigates the sounds and the anatomy of the sound-producing organ in the male and female sand-dwelling cusk-eel Parophidion vassali. Although both sexes have similar external phenotype, they can be distinguished by their sonic apparatus and sounds. As in many Ophioidei, Parophidion vassali presents a panel of highly derived characters.

Unravelling the structural variation of lizard osteoderms.

Vertebrate skin is a remarkable organ that supports and protects the body. It consists of two layers, the epidermis and the underlying dermis. In some tetrapods, the dermis includes mineralised organs known as osteoderms (OD).

Lizard osteoderms - Morphological characterisation, biomimetic design and manufacturing based on three species.

Osteoderms (OD) are mineralised dermal structures consisting mainly of calcium phosphate and collagen. The sheer diversity of OD morphologies and their distribution within the skin of lizards makes these reptiles an ideal group in which to study ODs. Nonetheless, our understanding of the structure, development, and function of lizard ODs remains limited.

A review of the osteoderms of lizards (Reptilia: Squamata).

Osteoderms are mineralised structures consisting mainly of calcium phosphate and collagen. They form directly within the skin, with or without physical contact with the skeleton. Osteoderms, in some form, may be primitive for tetrapods as a whole, and are found in representatives of most major living lineages including turtles, crocodilians, lizards, armadillos, and some frogs, as well as extinct taxa ranging from early tetrapods to dinosaurs.

Sound production in piranhas is associated with modifications of the spinal locomotor pattern.

In piranhas, sounds are produced through the vibration of the swim bladder wall caused by the contraction of bilateral sonic muscles. Because they are solely innervated by spinal nerves, these muscles likely evolved from the locomotor hypaxial musculature. The transition from a neuromuscular system initially shaped for slow movements (locomotion) to a system that requires a high contraction rate (sound production) was accompanied with major peripheral structural modifications, yet the associated neural adjustments remain to this date unclear.

Neuroanatomical and neurophysiological mechanisms of acoustic and weakly electric signaling in synodontid catfish.

To what extent do modifications in the nervous system and peripheral effectors contribute to novel behaviors? Using a combination of morphometric analysis, neuroanatomical tract-tracing, and intracellular neuronal recording, we address this question in a sound-producing and a weakly electric species of synodontid catfish, Synodontis grandiops, and Synodontis nigriventris, respectively. The same peripheral mechanism, a bilateral pair of protractor muscles associated with vertebral processes (elastic spring mechanism), is involved in both signaling systems. Although there were dramatic species differences in several morphometric measures, electromyograms provided strong evidence that simultaneous activation of paired protractor muscles accounts for an individual sound and electric discharge pulse.

Neurogenomic Profiling Reveals Distinct Gene Expression Profiles Between Brain Parts That Are Consistent in Cichlids.

The detection of external and internal cues alters gene expression in the brain which in turn may affect neural networks that underly behavioral responses. Previous studies have shown that gene expression profiles differ between major brain regions within individuals and between species with different morphologies, cognitive abilities and/or behaviors. A detailed description of gene expression in all macroanatomical brain regions and in species with similar morphologies and behaviors is however lacking.

Limited possibilities for prezygotic barriers in the reproductive behaviour of sympatric Ophthalmotilapia species (Teleostei, Cichlidae).

Since prezygotic rather than postzygotic barriers are believed to maintain the diversity of closely related sympatric cichlids, differences in phenotypic traits and reproductive behaviours are likely involved in maintaining species boundaries. Here, we focused on the reproductive behaviour of three Ophthalmotilapia species with distributions that only overlap on a small stretch of the shore line of Lake Tanganyika. Repeated introgression of mitochondrial DNA between these species was previously reported, which suggested they can hybridise.

Sound production mechanism in triggerfish (Balistidae): a synapomorphy.

The ability to produce sounds for acoustic communication is known in different Balistidae species but the eventual synapomorphic aspect of the mechanism remains to be shown. In , sounds result from alternate sweeping movements of the right and left pectoral fins, which push a system of three scutes against the swim bladder wall. In this study, we made a comparison between the sounds produced by this species and two additional ones ( and ) using hand-held specimens to provide a description of the sound mechanism.

Unusual sound production mechanism in the triggerfish Rhinecanthus aculeatus (Balistidae).

The ability to produce sound has been known for decades in Balistidae. Sounds of many species have been recorded and a variety of sound-producing mechanisms have been proposed, including teeth stridulation, collision of the buccal teeth and movements of the fins. The best-supported hypothesis involves movements of the pectoral fin against the lateral part of the swimbladder, called a drumming membrane.

Environmental constraints drive the partitioning of the soundscape in fishes.

The underwater environment is more and more being depicted as particularly noisy, and the inventory of calling fishes is continuously increasing. However, it currently remains unknown how species share the soundscape and are able to communicate without misinterpreting the messages. Different mechanisms of interference avoidance have been documented in birds, mammals, and frogs, but little is known about interference avoidance in fishes.

Sound production in Onuxodon fowleri (Carapidae) and its amplification by the host shell.

Onuxodon species are well known for living inside pearl oysters. As in other carapids, their anatomy highlights their ability to make sounds but sound production has never been documented in Onuxodon. This paper describes sound production in Onuxodon fowleri as well as the anatomy of the sound production apparatus.

A superfast muscle in the complex sonic apparatus of Ophidion rochei (Ophidiiformes): histological and physiological approaches.

In teleosts, superfast muscles are generally associated with the swimbladder wall, whose vibrations result in sound production. In Ophidion rochei, three pairs of muscles were named 'sonic' because their contractions affect swimbladder position: the dorsal sonic muscle (DSM), the intermediate sonic muscle (ISM), and the ventral sonic muscle (VSM). These muscles were investigated thanks to electron microscopy and electromyography in order to determine their function in sound production.

Hearing capacities and otolith size in two ophidiiform species (Ophidion rochei and Carapus acus).

Numerous studies have highlighted the diversity of fish inner ear morphology. However, the function of the shape, size and orientation of the different structures remains poorly understood. The saccule (otolithic endorgan) is considered to be the principal hearing organ in fishes and it has been hypothesized that sagitta (saccular otolith) shape and size affect hearing capacities: large sagittae are thought to increase sensitivity.

Modifications in call characteristics and sonic apparatus morphology during puberty in Ophidion rochei (Actinopterygii: Ophidiidae).

Juveniles, females, and males of Ophidion rochei share similar external morphology, probably because they are mainly active in the dark, which reduces the role of visual cues. Their internal sonic apparatuses, however, are complex: three pairs of sonic muscles, and highly modified vertebrae and ribs are involved in sound production. The sonic apparatus of males differs from juveniles and females in having larger swimbladder plates (modified ribs associate with the swimbladder wall) and sonic muscles, a modified swimbladder shape and a mineralized structure called the "rocker bone" in front of the swimbladder.

Sound production mechanism in Gobius paganellus (Gobiidae).

Gobiidae, the largest fish family (>1500 species), has species from at least 10 genera that produce sounds for communication. Studies focused on goby sound production mechanisms have suggested that sounds are produced by the forcible ejection of water through small apertures in the opercles (hydrodynamic mechanism). The present study was a multidisciplinary investigation (morphology, muscle histology, high-speed video, sound analysis and electromyography) of the sound emission mechanism in Gobius paganellus, which produces both pulsed and tonal calls.

Sexual dimorphism of sonic apparatus and extreme intersexual variation of sounds in Ophidion rochei (Ophidiidae): first evidence of a tight relationship between morphology and sound characteristics in Ophidiidae.

Background: Many Ophidiidae are active in dark environments and display complex sonic apparatus morphologies. However, sound recordings are scarce and little is known about acoustic communication in this family. This paper focuses on Ophidion rochei which is known to display an important sexual dimorphism in swimbladder and anterior skeleton.

The barbel-like specialization of the pelvic fins in Ophidion rochei (Ophidiidae).

Pelvic fins in Ophidion rochei are reduced to four rod-like structures situated at the ventral jaws. While the fish is swimming, they make continuous sweeping movements on the bottom. This paper examines and describes the anatomy of the pelvic fins to determine the possible functions of these appendages in relation to the mode of life of this fish species.