Featured Research

from universities, journals, and other organizations

Flap Over Fishes: Who's The Smallest Of Them All?

Date:
January 30, 2006
Source:
University of Washington
Summary:
The authors of a paper in last week's Proceedings of the Royal Society of London Section B, who say their 7.9 mm-long fish from a peat swamp in Southeast Asia is the smallest fish and vertebrate known, have failed to make note of work published last fall that describes sexually mature, male anglerfishes measuring 6.2 mm to 7.4 mm in length.

This 46 mm (1.8 inch) female Photocorynus spiniceps has what looks like a small nub in the middle of her back. Actually, that's a 6.2 mm (less than a quarter of an inch) long male, the world's smallest known, sexually mature vertebrate.
Credit: Photo T.W. Pietsch/University of Washington

The authors of a paper in this week's Proceedings of the Royal Society of London Section B, who say their 7.9 mm-long fish from a peat swamp in Southeast Asia is the smallest fish and vertebrate known, have failed to make note of work published last fall that describes sexually mature, male anglerfishes measuring 6.2 mm to 7.4 mm in length.

The 6.2 mm specimen is by far the smallest of any vertebrate, beating the recent claim by a full 1.7 mm, according to Ted Pietsch, a University of Washington professor of aquatic and fisheries sciences, who has described the specimen.

Pietsch includes information about the tiny specimen, collected in the Philippines, in a review of what's known about reproduction in anglerfishes, so called because they have bioluminescent lures growing from their heads that they wave or cause to blink in order to attract prey to their mouths. The work appeared in the September issue of Ichthyological Research, published by the Ichthyological Society of Japan.

In the "Summary and Conclusions" section of that paper, Pietsch wrote of specimens of Photocorynus spiniceps, the smallest of which was 6.2 mm. Pietsch has the histological evidence that it is a mature male.

The male is attached to the middle of the back of a 46 mm long female Photocorynus spiniceps because that is how they mate.

It's called sexual parasitism and in five of the 11 families of anglerfishes, the males are tiny compared to the females and fuse for life to their mates by biting onto the sides, backs or bellies of a female. An attached male -- even two, three or up to eight, depending on the family -- essentially turns the female into a hermaphrodite, providing her body with everything she needs to reproduce. For the task, the 6.2 mm male, for instance, has testes so huge they nearly fill his entire body cavity, crowding his other internal organs.

The female takes care of swimming, eating -- everything.

Anglerfishes live in deep water off both U.S. coasts and across the world's oceans. Home includes some of the most desolate stretches of the seafloor on Earth. Scientists estimate that 80 percent of the females, many of which live 25 or 30 years, never encounter a male. So it makes sense that anglerfish have evolved this strategy for reproducing, Pietsch says.

The sexually parasitic males don't have the lures typical of males of non-parasitic anglerfishes, instead their tiny bodies are dominated by nostrils -- to detect females -- and large eyes to scrutinize the female's lure. The male makes certain the female is of his family before biting onto her.

The specimen Pietsch describes is borrowed from the vertebrate collection of the Scripps Institution of Oceanography and his anglerfishes research is funded by the National Science Foundation. Along with including information in his published work, Pietsch's findings about the specimen were presented and illustrated at the Seventh Indo-Pacific Fish Conference in Taiwan last May.

"There are always difficulties in talking about the smallest -- would that be length, volume or weight -- the debate goes round and round," Pietsch says. The co-authors of the paper in the Proceedings of the Royal Society of London Section B, two of whom Pietsch knows, call the fish they found "the world's smallest vertebrate" and compare lengths.

They also compare numbers of vertebrae. On that count, Pietsch's Photocorynus spiniceps scores an 18 and Paedocypris progenetica, the subject of this week's paper, scores 33 to 35.

###

Pietsch's paper is posted on his personal UW Web site at http://uwfishcollection.org/staff/recent_publications.html. Reference to the smallest fishes is on page 232, in the "Summary and Conclusions" section of "Dimorphism, parasitism, and sex revisited: Modes of reproduction among deep-sea ceratioid anglerfishes "


Story Source:

The above story is based on materials provided by University of Washington. Note: Materials may be edited for content and length.


Cite This Page:

University of Washington. "Flap Over Fishes: Who's The Smallest Of Them All?." ScienceDaily. ScienceDaily, 30 January 2006. <www.sciencedaily.com/releases/2006/01/060130151906.htm>.
University of Washington. (2006, January 30). Flap Over Fishes: Who's The Smallest Of Them All?. ScienceDaily. Retrieved September 30, 2014 from www.sciencedaily.com/releases/2006/01/060130151906.htm
University of Washington. "Flap Over Fishes: Who's The Smallest Of Them All?." ScienceDaily. www.sciencedaily.com/releases/2006/01/060130151906.htm (accessed September 30, 2014).

Share This



More Plants & Animals News

Tuesday, September 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

California University Designs Sustainable Winery

California University Designs Sustainable Winery

Reuters - US Online Video (Sep. 27, 2014) — Amid California's worst drought in decades, scientists at UC Davis design a sustainable winery that includes a water recycling system. Vanessa Johnston reports. Video provided by Reuters
Powered by NewsLook.com
Argentina Worries Over Decline of Soybean Prices

Argentina Worries Over Decline of Soybean Prices

AFP (Sep. 27, 2014) — The drop in price of soy on the international market is a cause for concern in Argentina, as soybean exports are a major source of income for Latin America's third largest economy. Duration: 01:10 Video provided by AFP
Powered by NewsLook.com
Mama Bear, Cubs Hang out in California Backyard

Mama Bear, Cubs Hang out in California Backyard

Reuters - US Online Video (Sep. 27, 2014) — A mama bear and her two cubs climb trees, wrestle and take naps in the backyard of a Monrovia, California home. Vanessa Johnston reports. Video provided by Reuters
Powered by NewsLook.com
'Crazy' Climate Forces Colombian Farmers to Adapt

'Crazy' Climate Forces Colombian Farmers to Adapt

AFP (Sep. 26, 2014) — Once upon a time, farming was a blissfully low-tech business on Colombia's northern plains. Duration: 02:05 Video provided by AFP
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