Featured Research

from universities, journals, and other organizations

Smalleye pigmy sharks' bellies shine: They glow for camouflage

Date:
April 26, 2012
Source:
Journal of Experimental Biology
Summary:
Smalleye pigmy sharks have an eye-catching party trick: Their bellies glow. However, instead of being a giveaway, biologists have shown that the fish's shiny undersides probably provide camouflage. They also discovered that the pigmy shark and another glowing fish, the lantern shark, regulate their glow using the similar mechanisms, although the pigmy shark is probably more closely related to their common ancient ancestor.

Some sharks deserve a blood curdling reputation, but not the diminutive smalleye pigmy shark (Squaliolus aliae). Reaching a maximum length of only 22cm, the tiny animals are more likely to be on someone else's menu. Silhouetted against weak light penetrating from the surface, the tiny sharks should be most at risk from predators approaching from below. However, Julien Claes from Universitι catholique de Louvain, Belgium, explains that the minute sharks have evolved a handy trick. Their undersides are covered in tiny light-emitting photophores that probably fill in their telltale silhouettes.

Related Articles


Adding that the distantly related velvet belly lantern sharks have adopted this luminous tactic for camouflage and communication, Claes and colleague Jιrτme Mallefet were curious to discover whether pigmy sharks had acquired bioluminescence from the same origin, or developed the ability independently. The duo publish their discoveries that pigmy sharks glow for camouflage and that they probably share an ancestor in common with lantern sharks because they use similar mechanisms to regulate their glows in The Journal of Experimental Biology .

Teaming up with Hsuan-Ching Ho from the National Dong Hwa University, Taiwan, the scientists went trawling for smalleye pigmy sharks off the Taiwanese coast. Back in the lab, the team collected samples of the fish's skin, injected substances -- ranging from neurotransmitters to hormones, which are known to regulate a wide range of biological processes -- and waited to see whether the skin began glowing. Recording the time when the skin started producing light, and the maximum intensity and duration of light production, the team discovered that the hormone melatonin -- which stimulates light production in the lantern sharks -- made the smalleye pigmy shark's skin glow, while the neurotransmitters -- which regulate light production in deep-sea bony fish -- had no effect at all.

However, when the team applied prolactin to the glowing skin, they were in for a surprise: the glow faded. Instead of stimulating 30-min-long bursts of glowing light -- as it does for lantern sharks -- prolactin dimmed the sharks' glow, which, according to Claes, is intriguing from two perspectives.

He explains that in addition to using continual bioluminescence for camouflage, lantern sharks communicate using bursts of glowing of light from patches of skin on the pectoral and pelvic fins. They regulate this specific form of bioluminescence with the hormone prolactin. Having discovered that smalleye pigmy sharks use prolactin to inhibit light emission and that the photophores were restricted to the shark's lower surface, Claes and Mallefet concluded that instead of using bioluminescence for communication, the smalleye pigmy sharks use it purely for camouflage.

The team also explains that the lantern and pigmy sharks inherited their bioluminescence from an ancient predecessor, which used hormones to regulate skin pigmentation for camouflage. According to Claes, this ancient predecessor probably used melatonin to lighten the skin while using prolactin to darken the skin. The team says that smalleye pigmy and lantern sharks regulate their bioluminescence by adjusting the degree of pigmentation in cells covering the photophores. However, the pigmy shark has retained the pigment-mobilising effect of the ancestor's prolactin, which dims their glow by darkening the skin covering the photophores, whereas the lantern sharks have adapted prolactin to lighten the skin and emit light for communication. This suggests that the smalleye pigmy shark is more closely related to their ancient ancestor than the lantern shark.


Story Source:

The above story is based on materials provided by Journal of Experimental Biology. The original article was written by Kathryn Knight. Note: Materials may be edited for content and length.


Journal Reference:

  1. Claes, J. M., Ho, H.-C. and Mallefet, J. Control of luminescence from pigmy shark (Squaliolus aliae) photophores. J. Exp. Biol., 215, 1691-1699 DOI: 10.1242/%u200Bjeb.066704

Cite This Page:

Journal of Experimental Biology. "Smalleye pigmy sharks' bellies shine: They glow for camouflage." ScienceDaily. ScienceDaily, 26 April 2012. <www.sciencedaily.com/releases/2012/04/120426105707.htm>.
Journal of Experimental Biology. (2012, April 26). Smalleye pigmy sharks' bellies shine: They glow for camouflage. ScienceDaily. Retrieved December 19, 2014 from www.sciencedaily.com/releases/2012/04/120426105707.htm
Journal of Experimental Biology. "Smalleye pigmy sharks' bellies shine: They glow for camouflage." ScienceDaily. www.sciencedaily.com/releases/2012/04/120426105707.htm (accessed December 19, 2014).

Share This


More From ScienceDaily



More Plants & Animals News

Friday, December 19, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Navy Unveils Robot Fish

Navy Unveils Robot Fish

Reuters - Light News Video Online (Dec. 18, 2014) — The U.S. Navy unveils an underwater device that mimics the movement of a fish. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
Kids Die While Under Protective Services

Kids Die While Under Protective Services

AP (Dec. 18, 2014) — As part of a six-month investigation of child maltreatment deaths, the AP found that hundreds of deaths from horrific abuse and neglect could have been prevented. AP's Haven Daley reports. (Dec. 18) Video provided by AP
Powered by NewsLook.com
When You Lose Weight, This Is Where The Fat Goes

When You Lose Weight, This Is Where The Fat Goes

Newsy (Dec. 17, 2014) — Can fat disappear into thin air? New research finds that during weight loss, over 80 percent of a person's fat molecules escape through the lungs. Video provided by Newsy
Powered by NewsLook.com
The Hottest Food Trends for 2015

The Hottest Food Trends for 2015

Buzz60 (Dec. 17, 2014) — Urbanspoon predicts whicg food trends will dominate the culinary scene in 2015. Mara Montalbano (@maramontalbano) has the story. Video provided by Buzz60
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins