Internal vertebral morphology of bony fishes matches the mechanical demands of different environments

Abstract

Fishes have repeatedly evolved characteristic body shapes depending on how close they live to the substrate. Pelagic fishes live in open water and typically have narrow, streamlined body shapes; benthic and demersal fishes live close to the substrate; and demersal fishes often have deeper bodies. These shape differences are often associated with behavioral differences: pelagic fishes swim nearly constantly, demersal fishes tend to maneuver near the substrate, and benthic fishes often lie in wait on the substrate. We hypothesized that these morphological and behavioral differences would be reflected in the mechanical properties of the body, and specifically in vertebral column stiffness, because it is an attachment point for the locomotor musculature and a central axis for body bending. The vertebrae of bony fishes are composed of two cones connected by a foramen, which is filled by the notochord. Since the notochord is more flexible than bony vertebral centra, we predicted that pelagic fishes would have narrower foramina or shallower cones, leading to less notochordal material and a stiffer vertebral column which might support continuous swimming. In contrast, we predicted that benthic and demersal fishes would have more notochordal material, making the vertebral column more flexible for diverse behaviors in these species. We therefore examined vertebral morphology in 79 species using micro‐computed tomography scans. Six vertebral features were measured including notochordal foramen diameter, centrum body length, and the cone angles and diameters for the anterior and posterior vertebral cones, along with body fineness. Using phylogenetic generalized least squares analyses, we found that benthic and pelagic species differed significantly, with larger foramina, shorter centra, and larger cones in benthic species. Thus, morphological differences in the internal shape of the vertebrae of fishes are consistent with a stiffer vertebral column in pelagic fishes and with a more flexible vertebral column in benthic species.

Morphological examination of abdominal vertebral bodies from grass carp using high‐resolution micro‐CT scans

“…Previous studies supported the relationship between fish vertebral structure and their function in different living environments (Baxter et al, 2022;Donatelli et al, 2021;Friedman et al, 2020). The common occurrence of skeletal anomalies in farmed teleost fish and the absence of effective solutions is currently a major economic problem in aquaculture (Boglione et al, 2013).…”

Anatomy, 3D micro-CT and Semiquantitative Elemental Microanalysis in Common carp vertebrae (Cyprinus carpio; Linnaeus, 1758)

“…The higher surface-volume ratio of trabecular bone allows for extensive interaction with surrounding tissues, enhancing biomechanical responses such as increased bone remodeling and strength, observed in our histological analysis. The substantial presence of trabeculae also enhances the bone's capacity to distribute forces evenly, reducing the likelihood of fractures (Baxter et al, 2022;Sakashita et al, 2019). This trabecular architecture functions effectively under mechanical stress, distributing forces throughout the bone structure and providing a superior adaptation to diverse environmental conditions.…”

Bio-Model Selection, Processing and Results for Bio-Inspired Truck Streamlining

“…Such animals can live in air, water, or in both. Aerial animals cannot be used as a biomimetic model for our study because, in most cases, the beak is too prominent and only the body is streamlined [ 8 , 22 , 23 , 24 , 25 , 26 ]. Aquatic animals, particularly fish, are favored for our biomimetic study due to their often all-body streamlined shapes, including the beak/mouth.…”

“…Aquatic animals, particularly fish, are favored for our biomimetic study due to their often all-body streamlined shapes, including the beak/mouth. Fish can be characterized by the habitat they live in, grouping them as follows: pelagic fish, tuna; benthic fish, flounder; and demersal fish, trout [ 7 , 26 , 27 , 28 , 29 ].…”