Creature Feature: Pygmy Shark

Pgymy Shark

Today we are going to highlight one of the smallest known sharks. Not only is it small but there is still lots to learn and discover about this species. The Small-Eyed Pygmy Shark (Squaliolus aliae) can grow up to 8.6 inches. What a whopper! (Not really.) Like many deep sea organisms this species emits bioluminescence. There are a couple theories as to why these little sharks light up.

The first theory is that of predation. Some scientists speculate that Pygmy Sharks use their lights to lure prey within striking distance. Other smaller organisms in the deep sea will see little dots of light flickering in the water and go towards it thinking, “Yum! Food!” Once they get close though its MUNCH and into the belly of the Pygmy Shark.

The second theory is camouflage. Though fierce, this shark must still be on the lookout for predators as well as prey. Some hypothesize that the bioluminescent light helps the pygmy shark to blend in with the light coming from surface above. In this way, the Pygmy Shark can elude detection from creatures it could eat and those that might eat it back.

There is one thing we can say the Pygmy Shark’s lights are NOT used for, thanks to the hard work of scientific researchers. A study, called Control of luminescence from Pygmy Shark (Squaliolus aliae) photophores, concluded that the pygmy shark does not use their bioluminescence for communication, unlike another other glow-in-the-dark shark, the Lantern Shark. These two sharks seem to have evolved from a shared ancestor. However, it appears that the Pygmy Shark’s bioluminescence took a different evolutionary turn than the Lantern Shark. It retains a closer biological resemblance to its great-great-great-great grandma, who was also not a big talker (not through light communication anyway). Click here to read about this research in greater depth (pun ABSOLUTELY intended!)

There is so much to learn and discover in the world! It is never too late for students of all ages to get engaged, study, and explore!

References:
Edited by KC O’Shea
Photography from video clip 
http://www.sharks.org/species/pygmy-shark
http://news.nationalgeographic.com/news/2012/04/120430-glowing-shark-pygmy-claes-camouflage-science/
http://www.iucnredlist.org/details/60210/0
http://oceanexplorer.noaa.gov/gallery/livingocean/livingocean_fish.html
http://jeb.biologists.org/content/215/10/1691.abstract
Claes, J. M., Ho, H.-C. and Mallefet, J.
(2012). Control of luminescence from pygmy shark (Squaliolus aliae) photophores. J. Exp. Biol. 215, 1691–1699.

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