A Computational Study of the Hydrodynamics in the Nasal Region of a Hammerhead Shark (Sphyrna tudes): Implications for Olfaction
نویسندگان
چکیده
The hammerhead shark possesses a unique head morphology that is thought to facilitate enhanced olfactory performance. The olfactory chambers, located at the distal ends of the cephalofoil, contain numerous lamellae that increase the surface area for olfaction. Functionally, for the shark to detect chemical stimuli, water-borne odors must reach the olfactory sensory epithelium that lines these lamellae. Thus, odorant transport from the aquatic environment to the sensory epithelium is the first critical step in olfaction. Here we investigate the hydrodynamics of olfaction in Sphyrna tudes based on an anatomically-accurate reconstruction of the head and olfactory chamber from high-resolution micro-CT and MRI scans of a cadaver specimen. Computational fluid dynamics simulations of water flow in the reconstructed model reveal the external and internal hydrodynamics of olfaction during swimming. Computed external flow patterns elucidate the occurrence of flow phenomena that result in high and low pressures at the incurrent and excurrent nostrils, respectively, which induces flow through the olfactory chamber. The major (prenarial) nasal groove along the cephalofoil is shown to facilitate sampling of a large spatial extent (i.e., an extended hydrodynamic "reach") by directing oncoming flow towards the incurrent nostril. Further, both the major and minor nasal grooves redirect some flow away from the incurrent nostril, thereby limiting the amount of fluid that enters the olfactory chamber. Internal hydrodynamic flow patterns are also revealed, where we show that flow rates within the sensory channels between olfactory lamellae are passively regulated by the apical gap, which functions as a partial bypass for flow in the olfactory chamber. Consequently, the hammerhead shark appears to utilize external (major and minor nasal grooves) and internal (apical gap) flow regulation mechanisms to limit water flow between the olfactory lamellae, thus protecting these delicate structures from otherwise high flow rates incurred by sampling a larger area.
منابع مشابه
Diet and trophic level of scalloped hammerhead shark (Sphyrna lewini) from the Gulf of California and Gulf of Tehuantepec, Mexico
We examined the diet and trophic level of Sphyrna lewini in the Gulf of California (GC) during 2001 and in the Gulf of Tehuantepec (GT) during 2005 using data from stomach content and stable isotope analysis of δ15N and δ13C. S. lewini diet was represented by pelagic and benthic prey species where the most important in weight was Scomber japonicus (27.70±4.54%) in GC, while in GT it was Auxis s...
متن کاملFunctional morphology of the nasal region of a hammerhead shark.
We describe several novel morphological features in the nasal region of the hammerhead shark Sphyrna tudes. Unlike the open, rounded incurrent nostril of non-hammerhead shark species, the incurrent nostril of S. tudes is a thin keyhole-like aperture. We discovered a groove running anterior and parallel to the incurrent nostril. This groove, dubbed the minor nasal groove to distinguish it from t...
متن کاملDiet and trophic level of scalloped hammerhead shark (Sphyrna lewini) from the Gulf of California and Gulf of Tehuantepec, Mexico
We examined the diet and trophic level of Sphyrna lewini in the Gulf of California (GC) during 2001 and in the Gulf of Tehuantepec (GT) during 2005 using data from stomach content and stable isotope analysis of δ15N and δ13C. S. lewini diet was represented by pelagic and benthic prey species where the most important in weight was Scomber japonicus (27.70±4.54%) in GC, while in GT it was Auxis s...
متن کاملPhilopatry and Regional Connectivity of the Great Hammerhead Shark, Sphyrna mokarran in the U.S. and Bahamas
Citation: Guttridge TL, Van Zinnicq Bergmann MPM, Bolte C, Howey LA, Finger JS, Kessel ST, Brooks JL, Winram W, Bond ME, Jordan LKB, Cashman RC, Tolentino ER, Grubbs RD and Gruber SH (2017) Philopatry and Regional Connectivity of the Great Hammerhead Shark, Sphyrna mokarran in the U.S. and Bahamas. Front. Mar. Sci. 4:3. doi: 10.3389/fmars.2017.00003 Philopatry and Regional Connectivity of the G...
متن کاملCryptic hammerhead shark lineage occurrence in the western South Atlantic revealed by DNA analysis
A cryptic lineage of hammerhead shark closely related to but evolutionarily distinct from the scalloped hammerhead (Sphyrna lewini) was recently documented in the western North Atlantic Ocean. Here, we demonstrate using nuclear and mitochondrial DNA sequences that this cryptic lineage also occurs in the western South Atlantic Ocean, extending its distribution >7,000 km from its only previously ...
متن کامل