Hourglass Dolphin Case Study

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School size of Hourglass dolphins (Lagenorhynchus cruciger) affects predation Introduction The hourglass dolphin (Lagenorhynchus cruciger) is a pelagic marine dolphin which is circumpolar in the southern in both Antarctic and subantartic waters, from about 45°S to 60°S. (William F. Perrin, 2008). There is not enough data to determine with certainty the specific characteristics and traits of these species; as less than 20 specimens have been measured (Thomas A. Jefferson, 2015); however, from observation and sightings in is known that hourglass dolphins (Lagenorhynchus cruciger) tends to travel in groups, with a school size ranged between 1 and 60 animals, with a mean of 7 animals. (William F. Perrin, 2008). Like many other dolphins of the same family (Delphinidae) the hourglass dolphin (Lagenorhynchus cruciger) depend upon echolocation for prey localisation and orientation. Echolocation is the detection of an object by means of reflected sound (Allaby, 2014). Hourglass dolphins (Lagenorhynchus cruciger) produce echolocation click of high source level, which enable them to detect prey at more that twice the distance compared to the Hector …show more content…

If a school of a large size feeds more often than a school of a small size during the day or night, then the null hypothesis is rejected. If a school of a small size feeds more often than a school of a large size during the day or night, then we fail to reject the null hypothesis. If a school of a small size feeds equally as much as a school of a large size during the day and or night, then we fail to reject the null hypothesis.

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