Navigation Links
Harbor seals' whiskers as good at detecting fish as echolocating dolphins
Date:6/14/2010

When a hungry harbour seal sets off in pursuit of a fish diner, the animal has a secret weapon in its tracking arsenal: its whiskers. Detecting hydrodynamic trails in water with their sensitive whiskers, seals easily track passing fish even in the most turbid conditions. Wolf Hanke from the University of Rostock, Germany, explains that blindfolded seals can track passing mini-submarines for a distance of 40m before the wake peters out. However, the hydrodynamic trails left by subs are different from those produced by fish fins, so how long could a seal track a trail generated by a moving fin before the turbulence became too faint to follow? Hanke and his colleagues publish their discovery that the seals can pick up fin trails as long as 35s after the fin passed by on 11 June 2010 in The Journal of Experimental Biology at http://jeb.biologists.org.

PhD student Sven Wieskotten, together with Hanke, Guido Dehnhardt, Bjrn Mauck and Lars Miersch, decided to find out how 6-year-old Henry, a harbour seal living at the Marine Science Centre, Germany, would respond to ageing hydrodynamic trails. Isolating a section of calm water in a subsurface enclosure, Wieskotten and Hanke covered Henry's eyes with a blindfold and trained him to poke his head into the Perspex box a few seconds after they had swept a small rubber fin through the still water. Then they trained Henry to indicate which direction he thought the fin had moved by rewarding him with a tasty fish snack whenever he was correct.

After 2 months of training, Henry was ready to tell the team which direction he thought the fin was moving. Guided only by his whiskers, the team allowed Henry to swim into the enclosure 5s after the fin swept through the water and was delighted when Henry successfully identified which direction the fin had moved with over 90% accuracy. Gradually increasing the length of the delay, Wieskotten and his colleagues were amazed that even after a 35s delay Henry was able to tell them which direction the fin had passed with 70% accuracy. However, after a 40s delay, Henry lost the trail.

Curious to find out more about the fin's decaying trail, the team added microscopic spheres to the water and filmed them as they swirled through a plane of laser light. Analysing the particles' movements, they found spinning vortices producing jets of water that were very similar to those found in genuine fish wakes. Also, the wake became more dispersed as it decayed, covering a width of 20cm 5s after the fin swept past and expanding to 50cm 30s later. And when the team filmed the wake's interaction with Henry's whiskers, they could see Henry twitch his head in the direction that the fin had moved within 0.5s of the plume touching his whiskers. The wake only had to brush over the seal's whiskers for him to know which direction the fin had passed.

The team suspects that harbour seals sense the structure of the wake's vortices and jets to determine which direction a fin moved and is amazed that the animals can still detect a fin's motion over half a minute later. 'A fish can cover tens and hundreds of metres in that time, so vibrissae [whiskers] compare well with the performance of whales and dolphins by echolocation,' says Hanke.


'/>"/>

Contact: Kathryn Knight
kathryn@biologists.com
44-078-763-44333
The Company of Biologists
Source:Eurekalert

Related biology news :

1. Coral reef fish harbor an unexpectedly high biodiversity of parasites
2. From brains to behavior: Cold Spring Harbor Protocols features methods for neuroscience research
3. Cold Spring Harbor Protocols highlights a method that captures cell growth and activity
4. Cold Spring Harbor Laboratorys lung cancer research program awarded $100,000 grant
5. Cold Spring Harbor Laboratory to play central role addressing key questions in plant biology
6. RNA-based methods for developmental studies are featured in Cold Spring Harbor Protocols
7. San Diego Harbor Police Deploy BIO-key(R) Automated Vehicle Location System
8. Popular apple variety harbors unusual cell growth
9. Cold Spring Harbor Protocols features methods to screen genomes and analyze evolution
10. Cold Spring Harbor Laboratory scientists devise potential approach to treat spinal muscular atrophy
11. Sydney harbors deadly diet for sea creatures
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:5/6/2017)... SINGAPORE , May 5, 2017 ... has just announced a new breakthrough in biometric ... that exploits quantum mechanical properties to perform ... new smart semiconductor material created by Ram Group ... across finance, entertainment, transportation, supply chains and security. ...
(Date:4/19/2017)... New York , April 19, 2017 ... competitive, as its vendor landscape is marked by the ... the market is however held by five major players ... Safran. Together these companies accounted for nearly 61% of ... of the leading companies in the global military biometrics ...
(Date:4/17/2017)... Florida , April 17, 2017 NXT-ID, ... technology company, announces the filing of its 2016 Annual Report on ... and Exchange Commission. ... on Form 10-K is available in the Investor Relations section of ... as on the SEC,s website at http://www.sec.gov . ...
Breaking Biology News(10 mins):
(Date:6/22/2017)... , ... June 21, 2017 , ... ... office in North Carolina, and engages Timothy Reinhardt to manage the new site. ... leadership at Pfizer Inc, with his most recent role as the Director of ...
(Date:6/22/2017)... ... June 22, 2017 , ... For the months of ... a Spotlight series on “Cell Therapy Regulation” for its regenerative medicine ... on the unique regulatory challenges of stem cell medical research. , Stem cell ...
(Date:6/22/2017)... ... , ... Charm Sciences, Inc. is pleased to announce that its Charm Amphenicol ... as a screening test at dairies and farms for raw commingled cow milk. The ... EZ Lite system. These systems are a combination incubator and reader in one. , ...
(Date:6/20/2017)...  Kibow Biotech Inc., a pioneer in developing "Enteric ... a new patent covering a unique method for preventing ... and Trademark Office on May 23 rd 2017. ... Bio award in 2014 in San Diego, ... to chronic disease. Renadyl™, the first and only dietary ...
Breaking Biology Technology: