Creature Feature: Pelagic Thresher

Pelagic-thresher Jason Isley Arkive

With only a few weeks left of our year of shark features, it is time that I write about my absolute favorite shark, the Pelagic Thresher (Alopias pelagicus).There are three species of Thresher Sharks: the Pelagic Thresher, the Bigeye Thresher and the Common Thresher, plus scientists are looking into a possible fourth species of Thresher (yay!).

Data pertaining to the distribution of Pelagic Threshers is not always accurate because it is often miss-identified as a Common Thresher. However, by most accounts, Pelagic Threshers are found off the coast of Taiwan, California and Mexico. What are the physical characteristics that set threshers apart? Let’s start with the most notable feature, the caudal (tail) fin. In threshers, the upper lobe is extremely elongated. The sharks encircle schools of fish or squid and use this fin to whip the water and stun their prey. Pelagic Thresher Sharks have patches of dark coloration around the pectoral fins and do not have a labial furrows (shallow grooves around the lips). The Common Threshers do not have lateral cusplets (small projection on a tooth). The Bigeye Thresher has large eyes and have horizontal grooves on the top of their body.

Check out this video showing thresher sharks using their tails

Join us next week as to learn about retia mirabilia, a special circulatory system that the Pelagic Thresher use, as well as next week’s Creature Feature.

Edited By Felicia Van Stolk

Photography courtesy of ARKIVE (arkive.org): Jason Isley http://www.arkive.org/pelagic-thresher/alopias-pelagicus/image-G74893.html

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