Getting Nosy: Olfactory Rosette Morphology and Lamellar Microstructure of Two Chondrichthyan Species.

To smell, fish rely on passive water flow into their olfactory chambers and through their olfactory rosettes to detect chemical signals in their aquatic environment. The olfactory rosette is made up of secondarily folded tissues called olfactory lamellae. The olfactory morphology of cartilaginous fishes varies widely in both rosette gross morphology and lamellar microstructure.

Vertebral morphology in the tail-whipping common thresher shark, .

Thresher sharks ( spp.) are characterized by an elongated, scythe-like caudal fin that is used in tail-whipping, a behaviour where the tail is thrown overhead to stun prey. Tail-whipping is performed via extreme dorsoventral bending of the vertebral column, and is dramatically different from lateral oscillatory motion used for swimming.

Morphometric analysis of the elasmobranch olfactory rosette.

The olfactory rosettes of elasmobranchs vary in shape and structure among species, but the functional consequences of this diversity are unresolved. Our goal was to quantify rosette morphology on dissected as well as diffusible iodine-based contrast-enhanced computed tomography (diceCT)-imaged specimens to analyze the drivers of observed trends in a phylogenetic context and compare the methodologies. We hypothesized that lamellar count and rosette shape (fineness ratio) would not scale with animal size, but other rosette size variables would scale positively.

Two heads are not always better than one: Craniofacial and axial bifurcation in cheloniid embryos and hatchlings (Chelonia mydas and Caretta caretta).

Morphological data on craniofacial and axial bifurcation in sea turtles is not well documented in the literature. Here, we use micro-computed tomography (μ-CT) imaging to describe the body, skull, and vertebral morphology in axially-bifurcated cheloniid sea turtle embryos and hatchlings (Chelonia mydas and Caretta caretta) from south Florida beaches. We describe three types of craniofacial and axial bifurcations: bifacial, bicephalic, and bicephalic with biaxial duplication ranging from facial bones to the sacrum.

Damsels in Distress: Oil Exposure Modifies Behavior and Olfaction in Bicolor Damselfish ().

In fishes, olfactory cues evoke behavioral responses that are crucial to survival; however, the receptors, olfactory sensory neurons, are directly exposed to the environment and are susceptible to damage from aquatic contaminants. In 2010, 4.9 million barrels of crude oil were released into the northern Gulf of Mexico from the disaster, exposing marine organisms to this environmental contaminant.

Leptin's effect on taste bud calcium responses and transmitter secretion.

Leptin, a peptide hormone released by adipose tissue, acts on the hypothalamus to control cravings and appetite. Leptin also acts to decrease taste responses to sweet substances, though there is little detailed information regarding where leptin acts in the taste transduction cascade. The present study examined the effects of leptin on sweet-evoked responses and neuro transmitter release from isolated taste buds.

The somatotopic organization of the olfactory bulb in elasmobranchs.

The olfactory bulbs (OBs) are bilaterally paired structures in the vertebrate forebrain that receive and process odor information from the olfactory receptor neurons (ORNs) in the periphery. Virtually all vertebrate OBs are arranged chemotopically, with different regions of the OB processing different types of odorants. However, there is some evidence that elasmobranch fishes (sharks, rays, and skates) may possess a gross somatotopic organization instead.

Sensitivity and specificity of the olfactory epithelia of two elasmobranch species to bile salts.

Odor detection in vertebrates occurs when odorants enter the nose and bind to molecular olfactory receptors on the cilia or microvilli of olfactory receptor neurons (ORNs). Several vertebrate groups possess multiple, morphologically distinct types of ORNs. In teleost fishes, these different ORN types detect specific classes of biologically relevant odorants, such as amino acids, nucleotides and bile salts.

Olfactory morphology and physiology of elasmobranchs.

Elasmobranch fishes are thought to possess greater olfactory sensitivities than teleost fishes due in part to the large amount of epithelial surface area that comprises their olfactory organs; however, direct evidence correlating the size of the olfactory organ to olfactory sensitivity is lacking. This study examined the olfactory morphology and physiology of five distantly related elasmobranch species. Specifically, we quantified the number of lamellae and lamellar surface area (as if it were a flat sheet, not considering secondary lamellae) that comprise their olfactory organs.