Rapid pupil change in selachians

1981 ◽  
Vol 59 (3) ◽  
pp. 560-564 ◽  
Author(s):  
P. W. Gilbert ◽  
J. G. Sivak ◽  
R. E. Pelham
Keyword(s):  
Shark Species ◽  
Pupil Control ◽  
Pupil Response ◽  
Negaprion Brevirostris ◽  
Ginglymostoma Cirratum

Pupil response was studied photographically in four shark species: Ginglymostoma cirratum, Carcharhinus milberti, Negaprion brevirostris, and Galeocerdo cuvieri. Constriction and dilation take place in significantly less than 1 min in three of the four species. These rates suggest that pupil control is neuromuscular in some sharks.

scholarly journals Description of the microbiota in epidermal mucus and skin of sharks (Ginglymostoma cirratum and Negaprion brevirostris) and one stingray (Hypanus americanus)

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e10240
Author(s):  
Susana Caballero ◽  
Ana Maria Galeano ◽  
Juan Diego Lozano ◽  
Martha Vives
Keyword(s):  
Microbial Communities ◽  
Pathogenic Bacteria ◽  
Rrna Gene ◽  
Shark Species ◽  
Lemon Shark ◽  
Skin Mucus ◽  
Negaprion Brevirostris ◽  
Opportunistic Bacteria ◽  
Ginglymostoma Cirratum ◽  
Skin Samples

Skin mucus in fish is the first barrier between the organism and the environment but the role of skin mucus in protecting fish against pathogens is not well understood. During copulation in sharks, the male bites the female generating wounds, which are then highly likely to become infected by opportunistic bacteria from the water or from the male shark’s mouth. Describing the microbial component of epithelial mucus may allow future understanding of this first line of defense in sharks. In this study, we analyzed mucus and skin samples obtained from 19 individuals of two shark species and a stingray: the nurse shark (Ginglymostoma cirratum), the lemon shark (Negaprion brevirostris) and the southern stingray (Hypanus americanus). Total DNA was extracted from all samples, and the bacterial 16S rRNA gene (region V3-V4) was amplified and sequenced on the Ion Torrent Platform. Bacterial diversity (order) was higher in skin and mucus than in water. Order composition was more similar between the two shark species. Alpha-diversities (Shannon and Simpson) for OTUs (clusters of sequences defined by a 97% identity threshold for the16S rRNA gene) were high and there were non-significant differences between elasmobranch species or types of samples. We found orders of potentially pathogenic bacteria in water samples collected from the area where the animals were found, such as Pasteurellales (i.e., genus Pasteurella spp. and Haemophilus spp.) and Oceanospirillales (i.e., genus Halomonas spp.) but these were not found in the skin or mucus samples from any species. Some bacterial orders, such as Flavobacteriales, Vibrionales (i.e., genus Pseudoalteromonas), Lactobacillales and Bacillales were found only in mucus and skin samples. However, in a co-occurrence analyses, no significant relationship was found among these orders (strength less than 0.6, p-value > 0.01) but significant relationships were found among the order Trembayales, Fusobacteriales, and some previously described marine environmental Bacteria and Archaea, including Elusimicrobiales, Thermoproteales, Deinococcales and Desulfarculales. This is the first study focusing on elasmobranch microbial communities. The functional role and the benefits of these bacteria still needs understanding as well as the potential changes to microbial communities as a result of changing environmental conditions.

Functional morphology of the olfactory organ of two carcharhinid shark species

1987 ◽  
Vol 65 (10) ◽  
pp. 2406-2412 ◽  
Author(s):  
Eckart Zeiske ◽  
Birgit Theisen ◽  
Samuel H. Gruber
Keyword(s):  
Ventral Side ◽  
Sensory Epithelium ◽  
Shark Species ◽  
Basal Cells ◽  
Lemon Shark ◽  
Negaprion Brevirostris ◽  
Receptor Cells ◽  
Silky Shark ◽  
Inlet Chamber ◽  
Outlet Chamber

The paired olfactory organs of both the lemon shark (Negaprion brevirostris) and the silky shark (Carcharhinus falciformis) are located in solid cartilaginous nasal capsules, which open at the ventral side of the snout and are entirely separate from the mouth. The olfactory rosette consists of two rows of lamellae arising from a central raphe. The lamellae possess secondary folds covered with sensory epithelium, which contains microvillous receptor cells, supporting cells with both cilia and microvilli, basal cells, and goblet cells. No ciliated receptor cells were found. Gaps between facing lamellae connect the inlet chamber with the outlet chamber. The inlet chamber receives the ventilatory water through the incurrent nostril and the outlet chamber discharges the water through the excurrent nostril. A nasal flap, a septum, and paired valve flaps form an incomplete barrier between incurrent and excurrent nostrils and may have hydrodynamic functions, which are discussed.

Bacterial Hydrolysis of Urea in the Tissues of Carcharhinid Sharks

1988 ◽  
Vol 45 (2) ◽  
pp. 357-360 ◽  
Author(s):  
Ivor T. Knight ◽  
D. Jay Grimes ◽  
Rita R. Colwell
Keyword(s):  
Urea Hydrolysis ◽  
Shark Species ◽  
Blood Samples ◽  
Negaprion Brevirostris ◽  
Liver Homogenates ◽  
Hydrolysis Of ◽  
Ureolytic Bacteria ◽  
Hydrolysis Of Urea

Ureolytic activity was detected in liver homogenates of two carcharhinid shark species, Galeocerdo cuvieri and Negaprion brevirostris, employing 14C-labeled urea to monitor mineralization over 48 h. Significant (P < 0.05) urea hydrolysis was detected in liver homogenates within 48 h whereas no hydrolysis was detected in homogenates incubated with either ampicillin or the vibriostatic agent O/129, indicating bacterial mediation of the ureolytic activity. Urea hydrolysis could not be detected in blood samples. The autochthonous microflora of sharks has been found to contain ureolytic bacteria, and the present study supports the conclusion that they are present in organ tissues of healthy sharks but are not present in the blood.

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