The research team, led by postdoctoral researcher Yu Zeng and integrative biology professor Stephen Deban, employed decade-spanning high-speed video analysis to investigate the kinematics of tongue projection in these animals. They observed that both salamanders and chameleons can deploy their tongues at speeds reaching an impressive 16 feet per second. This “slingshot” mechanism relies not on specialized, exotic tissues but rather on the common vertebrate anatomical components—ordinary muscle, tendons, and bone—maximizing elastic energy storage and rapid release during tongue projection.

At the heart of this convergent evolutionary adaptation lies a complex interplay of linear actuators fashioned by the arrangements of tendinous and muscular structures. These biological systems act as capacitors of mechanical energy: muscles slowly preload elastic tissues, which then release energy in rapid, power-amplified bursts that propel the tongue towards prey with breathtaking speed. The analogy to a slingshot is precise—not merely visual but mechanistic—representing a unifying biomechanical strategy that transcends evolutionary distance.

This discovery expands the field of bioinspiration by illustrating how seemingly mundane biological tissues, when arranged in specific configurations, can produce extraordinary functional outcomes. Unlike more commonly studied systems that evolve novel materials or structures, these animals showcase how evolutionary ingenuity can arise from novel usage of ubiquitous anatomical elements. For engineers, this indicates a potentially fertile avenue for developing scalable linear actuators using widely available materials in biomedical devices or robotics.

From an engineering perspective, the implications are profound. The USF team is already exploring how to translate these biomechanical principles into practical applications. The capacity to generate fast, precise, and scalable motion could revolutionize medical instruments designed to navigate delicate bodily environments. For instance, devices inspired by this mechanism could clear vascular blockages by deploying rapid, controlled protrusions without requiring bulky or rigid components.

Beyond medicine, the implications stretch to disaster recovery and space exploration. Tools modeled after the ballistic tongue actuators may retrieve objects from collapsed buildings or grab debris in space, operating effectively in environments where dexterity, speed, and delicacy are critical. The scalability of the design—from millimeter-scale biomedical devices to meter-scale robotic appendages—makes it a versatile engineering template.

Biomechanically, the convergence observed challenges previous conceptions about how evolutionary pressures influence anatomical innovation. While chameleons and salamanders occupy distinct ecological niches and differ widely in their phylogenetic lineage, they converged upon functionally analogous mechanical solutions—highlighting nature’s economy in reusing successful designs. This convergence also provokes questions about the evolutionary pathways and genetic mechanisms leading to such analogous morphologies in distantly related lineages.

Further investigations by the research group aim to delineate the muscular and tendinous dynamics involved in tongue retraction—a phase as important and rapid as effectuation of the strike. Understanding the feedback and control mechanisms that govern retraction could unlock additional bioinspired approaches to designing fast-resetting actuators and compliant robotic systems. These insights form part of a growing scientific movement embracing “bioinspiration,” where lessons drawn from evolutionary solutions guide novel technological advances.

Professor Deban, reflecting on decades of study into animal locomotion and biomechanics, emphasizes the fusion of biology and engineering as a powerful driver of innovation. Whereas earlier work focused largely on cataloging and understanding biological performances, current efforts aim to decode and adapt these strategies into technologies that meet emerging human challenges. This bridging of disciplines is emblematic of a broader trend in science—embracing interdisciplinarity to accelerate discovery and application.

Video analyses and mechanical modeling underpin the robustness of the USF team’s findings. By positioning salamanders and chameleons side by side within experimental protocols, the researchers generated a comparative framework that revealed both the similarities and nuances in function, timing, and morphology. This integrative approach, leveraging biology, physics, and engineering, exemplifies the increasingly collaborative nature of modern scientific inquiry.

The study not only enriches evolutionary biology but also invites reexaminations of other systems where convergent mechanical strategies might be hiding in plain sight. It encourages cross-taxonomic comparisons and fuels curiosity about the latent possibilities residing in common anatomical components across life forms. Such work demonstrates how transformational discoveries often emerge at the intersection of disciplines and perspectives.

In sum, the University of South Florida’s groundbreaking work on the ballistic tongues of salamanders and chameleons is a testament to the power of fundamental research married to visionary application. The team’s elucidation of a shared evolutionary design packaged within everyday biological materials paves new pathways for technological innovation inspired by the living world. As bioinspired engineering continues to evolve, such discoveries will undoubtedly inspire the next generation of adaptive tools, devices, and machines capable of solving complex problems both on Earth and beyond.

Subject of Research: Animals
Article Title: Convergently evolved linear actuators in ballistic tongues
News Publication Date: 8-Sep-2025
Web References:

• Study published in Current Biology: https://www.cell.com/current-biology/fulltext/S0960-9822(25)01030-9?rss=yes
• Deban Laboratory website: https://sites.google.com/view/debanlab
• Researcher Yu Zeng’s page: https://yuzeng.org/
• University of South Florida: https://www.usf.edu/index.aspx
  Image Credits: Credit: USF
  Keywords: Evolutionary biology, Biomedical engineering, Mechanical engineering

Traditionally, vertebrate jaws have been classified largely by their vertical articulation—an up-and-down motion optimized for capturing and processing food. Mammals, for instance, employ intricate multi-axis jaw movements, including lateral motions, enabling mastication that breaks down tough plant material. Such complex jaw function is considered largely absent in most fish species, whose feeding typically involves suction mechanisms to engulf free-floating prey. The discovery that reef fishes can similarly move their jaws from side to side marks a significant departure from this paradigm, indicating that lateral jaw motions have evolved in some aquatic lineages to meet the unique demands of reef herbivory.

This rare biomechanical feature was first documented in high-speed video analyses conducted by postdoctoral researcher Michalis Mihalitsis, then at UC Davis. By recording the rapid feeding behavior of Zanclus cornutus, Mihalitsis observed jaw movements so swift and subtle that they eluded naked-eye detection. Subsequent computed tomography (CT) scans and detailed dissections corroborated these observations, confirming both the upper and lower jaws’ ability to execute precise lateral motions. Such dynamic lateral flexibility allows the Moorish Idol to effectively extract algae and other sessile organisms from reef crevices—an ecological niche that demands both agility and forceful manipulation in confined spaces.

Expanding upon this initial discovery, Mihalitsis and senior author Peter Wainwright examined the surgeonfish family (Acanthuridae), a diverse and ecologically dominant group of herbivorous reef fishes. Surgeonfish feed primarily by browsing dense turf algae that coat reef substrates. Detailed biomechanical studies revealed that these fishes employ lateral jaw movements primarily through their upper jaw, enabling them to shear and slice strands of algae efficiently. This specialized jaw movement enhances their ability not only to procure energy-rich benthic vegetation but also to outcompete other reef herbivores by increasing feeding speed and precision.

From an evolutionary standpoint, lateral jaw mobility in these reef species appears to represent a significant functional adaptation that has been selectively favored to exploit the challenging, three-dimensional food environment of coral reefs. Reef ecosystems are characterized by complex microhabitats where food resources such as algae often reside within cracks, crevices, and tough rock surfaces. Flexible jaw mobility confers the ability to generate multidirectional forces necessary to access and dislodge such food, without relying solely on suction or biting forces orthogonal to the reef surface.

The evolutionary implications extend beyond mere feeding efficiency; this biomechanical adaptation may partially explain the remarkable success and diversity of reef herbivores within their ecological niches. Lateral jaw motion allows these fishes to minimize foraging time while maximizing energy intake, which is critical within ecosystems where competition for algal resources is intense. Additionally, the ability to manipulate food items effectively may reduce interspecific competition by partitioning feeding strategies among reef fishes.

Importantly, this adaptation appears to have arisen convergently in at least two reef fish lineages, suggesting a strong selective pressure in reef environments favoring jaw mobility innovations. While lateral jaw movement is virtually absent in most vertebrate fishes, its independent emergence in surgeonfish and Moorish Idols underscores the evolutionary plasticity of vertebrate jaw systems in response to ecological demands.

The research utilized an integrative methodological approach. High-speed videography captured feeding kinematics with temporal resolution sufficient to resolve rapid jaw movements invisible to the human eye. Advanced imaging techniques such as micro-CT scans provided anatomical insights into mandibular articulations and muscular arrangements enabling lateral mobility. Complementary dissections confirmed structural modifications in skeletal and muscular components facilitating this unique jaw function, shedding light on the interplay between morphology and function.

Moreover, the study’s authors recognized the potential that additional benthic-feeding reef fishes could harbor similar lateral jaw adaptations, prompting ongoing investigations into the broader prevalence and ecological significance of this trait. Such research could reveal novel biomechanical strategies underpinning feeding diversity and efficiency in coral reef communities, with broader implications for understanding vertebrate evolution.

These findings not only enrich the understanding of vertebrate functional morphology but also highlight the complex evolutionary dynamics shaping reef ecosystems, where mechanical innovations translate into ecological dominance. By showcasing the unexpected versatility of fish jaws, the study opens avenues for future research into how morphological novelties facilitate niche diversification and adaptive radiations in vertebrates.

This discovery has garnered attention across evolutionary biology and functional morphology disciplines, emphasizing the need to reevaluate assumptions about vertebrate feeding mechanisms. As reef systems face mounting environmental pressures, understanding the intricacies of trophic interactions driven by such biomechanical innovations becomes increasingly crucial for conservation and management efforts.

In conclusion, the identification of lateral jaw movement in reef fishes represents a pivotal advance in the study of vertebrate biomechanics. Through a combination of high-resolution video capture and anatomical analysis, researchers have highlighted how seemingly subtle morphological variations can underpin profound ecological and evolutionary success. This biomechanical innovation exemplifies the intricate adaptations that have enabled reef fishes to thrive in complex and competitive environments, offering new insights into the multifaceted nature of vertebrate functional diversity.

Subject of Research: Animals
Article Title: Lateral jaw motion in fish expands the functional repertoire of vertebrates and underpins the success of a dominant herbivore lineage
News Publication Date: 5-May-2025
Web References: https://doi.org/10.1073/pnas.2418982122
References: Proceedings of the National Academy of Sciences, 2025
Keywords: Evolutionary biology, Animal anatomy, Ichthyology