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Horn Sharks and Swell Sharks Behavior and Interactions Researchand presentation done by: Amihan Arroyo, Anneka Christie, and Alex Lopez
Our Research Project • Observing the Horn Shark and Swell Shark in the touch tank on campus • We wanted to see whether or not the amount of physical activity of both sharks changed due to time of day. • Also, if they displayed different social behaviors at day or night. • Our research question: Do the sharks in the tanks social interactions with other organisms change during different hours of the day?
The Swell Shark Cephaloscyllium ventriosum • Habitat and Region: Prefers kelp forests, caves, rock crevices and bottoms in order to hide. Found around the southern tip of Mexico, along California’s coasts, and in the Eastern Pacific. • Diet: crustaceans and fish • Size: Can grow up to 3 feet • When the swell shark feels threatened, it ‘swells’ up to twice its body size.
The Horn Shark Heterodontus francisci • Habitat and Range: The Horn Shark lives in kelp forests and other habitats similar to the swell shark. This species can be found from Central California to Baja California • Diet: mollusks, crustaceans, small fish, sea urchins • Size: Can grow up to 4 feet • The horns’ before each of their dorsal fins are actually spines.
We believe that the sharks in the touch tank will be more active during the night time. This is because we have background knowledge that both species of sharks are nocturnal animals. We are also curious to see which behaviors they exhibit during these hours, and which organisms they interact with. Horn Shark Our Hypothesis Swell Shark
Procedures • Observed the sharks at touch tank for 15 minute intervals. • Wrote down detailed observations about their activity. • Logged and organized collected information daily
Controls • Sharks in tank (amount and species) • 15 minutes observations in a controlled habitat Variables • time of day (independent) • sharks activity and location (dependent) External Factors • Feeding times • Unnatural lighting • Veterinarian arrived on 6/28 between 9:00a.m.- 12:30p.m. Controls and Variables Due to the fact that our project was mostly observational, we didn’t have many controls or variable present in our research.
Observations • We concluded that both sharks were significantly more active at night. This means that our hypothesis was correct. • We also noticed that both sharks had very different behavioral systems. The Swell Shark was a lot more tolerant of other organisms, while the Horn Shark was easily disturbed by other animals. • While the Horn Shark’s activity slightly increased at night, it never reached the same level of activity as the Swell Shark.
Significance We decided to research this particular project because we were looking forward to learning more about these species. We hope our research will help scientists to study these sharks in captivity. Why study this topic?
Things We Can Change To extend this experiment… • For night observations, determine if the presence of light effected their behavior. • Research in their natural environment. • Study sharks of different age and gender to reflect the whole species. • Study how sharks of the opposite sex interact with each other at different times during mating seasons.
Acknowledgements • Special thanks to… • Linda Chilton for all of her great help, support, and knowledge • USC WIES, C DEBI, Sea Grant, and Staff for this amazing opportunity • Kellie Spafford ( Marine Lab Technician) for answering all of our questions above and beyond • Mason Clark (seasonal lab assistant) for helping us find information about the sharks • Cleveland Richardson for helping us research for credible sources • (a.k.a. book finder)
Bibliography Castro, Jose Ignacio. The Sharks of North American Waters. College Station, TX: Texas A&M UP,1996. Print. Russo, Ron. Pacific Coast Fish: A Guide to Marine Fish of the Coast of North America. Berkeley, CA: Nature Study Guild, 1990. Print. https://www.montereybayaquarium.org. "Swell Sharks.”, Cephaloscyllium ventriosum. Monterey Bay Aquarium. N.p., n.d. Web. 28 June 2013. https://www.montereybayaquarium.org. "Horn Shark." , Kelp Forest, Fishes, Heterodontus Francisci. N.p., n.d. Web. 28 June 2013.
Questions? Thank You!! We hope our presentation didn’t make you do this…