Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Flap over fishes: Who’s the smallest of them all?

31.01.2006


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.



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. 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.

Sandra Hines | EurekAlert!
Further information:
http://www.washington.edu.
http://uwfishcollection.org/staff/recent_publications.html

More articles from Life Sciences:

nachricht New risk factors for anxiety disorders
24.02.2017 | Julius-Maximilians-Universität Würzburg

nachricht Stingless bees have their nests protected by soldiers
24.02.2017 | Johannes Gutenberg-Universität Mainz

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>