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Osprey, FL, United States

Schmidt J.V.,University of Illinois at Chicago | Schmidt J.V.,Shark Research Institute | Chen C.-C.,National Taiwan Ocean University | Sheikh S.I.,University of Illinois at Chicago | And 5 more authors.
Endangered Species Research | Year: 2010

A 10.6 m female whale shark Rhincodon typus caught off the coast of eastern Taiwan in 1995 carried 304 embryos that ranged in developmental stage from individuals still in egg cases to hatched and free-swimming near-term animals. This litter established that whale sharks develop by aplacental yolk-sac viviparity, with embryos hatching from eggs within the female. The range of developmental stages in this litter suggested ongoing fertilization over an extended period of time, with embryos of different ages possibly sired by different males. A series of 9 microsatellite markers for R. typus have now been used to investigate paternity in a subset of these embryos. We determined the paternity of 29 embryos representing 10% of the original litter, and spanning most of the range of size and developmental stage of the 304 embryos. All were full siblings sired by the same male, suggesting that this male may have sired the entire litter. Probability analysis indicates that a second male could go undetected if it sired less than 10% of the litter. The range of developmental stages of embryos from this single sire further suggests that female whale sharks may have the ability to store sperm for later fertilization. In the absence of any tissue to determine parental genotypes, maternal mitochondrial sequence was obtained from the embryos, identifying a novel haplotype linked to those from the western Indian Ocean. This finding adds further support for the global population structure emerging for R. typus. © Inter-Research 2010. Source

Ritter E.K.,Shark Research Institute | Compagno L.J.V.,Stellenbosch University
Marine Biodiversity Records | Year: 2013

A video clip from the Galápagos Archipelago confirms the first recording of the smalltooth sandtiger shark, Odontaspis ferox, in these islands. Further sightings of this species in the eastern Pacific will likely follow, considering that other, relatively nearby islands lay within reach of the Equatorial Counter Current and North Equatorial Current, which connect some already reported sightings. © Marine Biological Association of the United Kingdom 2013. Source

Although chafing-the rubbing of a body on the sea floor-is a common response of sharks to the attachment of irritating sharksuckers (Echeneis spp.), this behavior has not yet been analyzed in detail. I focused on the different forms and functions of chafing, with special emphasis on the use of sand ripples by sharks during chafing. A significant number of the 146 videotaped Caribbean reef sharks, Carcharhinus perezi (Poey, 1876), and blacktip sharks, Carcharhinus limbatus (Müller and Henle, 1839), preferred to chafe against sand ripples with either a parallel or perpendicular swim direction rather than a transverse swim direction. Tailbeat frequencies of the different forms of the chafing behavior were significantly larger than cruising frequencies. Results indicate that successful chafing requires that sharks employ pattern-recognition and body awareness during chafing. © 2011 Rosenstiel School of Marine and Atmospheric Science of the University of Miami. Source

Unger N.R.,Nova Southeastern University | Ritter E.,University of West Florida | Ritter E.,Shark Research Institute | Borrego R.,St Marys Medical Center | And 2 more authors.
PLoS ONE | Year: 2014

Sharks possess a variety of pathogenic bacteria in their oral cavity that may potentially be transferred into humans during a bite. The aim of the presented study focused on the identification of the bacteria present in the mouths of live blacktip sharks, Carcharhinus limbatus, and the extent that these bacteria possess multi-drug resistance. Swabs were taken from the oral cavity of nineteen live blacktip sharks, which were subsequently released. The average fork length was 146 cm (±11), suggesting the blacktip sharks were mature adults at least 8 years old. All swabs underwent standard microbiological work-up with identification of organisms and reporting of antibiotic susceptibilities using an automated microbiology system. The oral samples revealed an average of 2.72 (±1.4) bacterial isolates per shark. Gram-negative bacteria, making up 61% of all bacterial isolates, were significantly (p<0.001) more common than gram-positive bacteria (39%). The most common organisms were Vibrio spp. (28%), various coagulase-negative Staphylococcus spp. (16%), and Pasteurella spp. (12%). The overall resistance rate was 12% for all antibiotics tested with nearly 43% of bacteria resistant to at least one antibiotic. Multi-drug resistance was seen in 4% of bacteria. No association between shark gender or fork length with bacterial density or antibiotic resistance was observed. Antibiotics with the highest overall susceptibility rates included fluoroquinolones, 3rd generation cephalosporins and sulfamethoxazole/trimethoprim. Recommended empiric antimicrobial therapy for adult blacktip shark bites should encompass either a fluoroquinolone or combination of a 3rd generation cephalosporin plus doxycycline. © 2014 Unger et al. Source

Ritter E.K.,Shark Research Institute | Amin R.,University of West Florida
Animal Cognition | Year: 2014

The present study examines the potential capability of Caribbean reef sharks to perceive human body orientation, as well as discussing the sharks' swimming patterns in a person's vicinity. A standardized video method was used to record the scenario of single SCUBA divers kneeling in the sand and the approach patterns of sharks, combined with a control group of two divers kneeling back-to-back. When approaching a single test-subject, significantly more sharks preferred to swim outside the person's field of vision. The results suggest that these sharks are able to identify human body orientation, but the mechanisms used and factors affecting nearest distance of approach remain unclear. © 2013 Springer-Verlag Berlin Heidelberg. Source

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