Navigation Links
Harbor seals' whiskers as good at detecting fish as echolocating dolphins

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

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
The Company of Biologists

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:
(Date:10/29/2015)... 29, 2015  The J. Craig Venter Institute (JCVI) ... Synthesis and Biosecurity: Lessons Learned and Options for the ... and Human Services guidance for synthetic biology providers has ... --> --> Synthetic biology ... potential to pose unique biosecurity threats. It now is ...
(Date:10/29/2015)... 2015  Rubicon Genomics, Inc., today announced an ... its DNA library preparation products, including the ThruPLEX ... Plasma-seq kit. ThruPLEX Plasma-seq has been optimized for ... libraries for liquid biopsies--the analysis of cell-free circulating ... in cancer and other conditions. Eurofins Scientific is ...
(Date:10/29/2015)... OXFORD, Connecticut , October 29, 2015 /PRNewswire/ ... "Company"), a biometric authentication company focused on the ... Wocket® smart wallet announces that StackCommerce, a leading ... will be featuring the Wocket® smart wallet on ... NXTD ) ("NXT-ID" or the "Company"), a ...
Breaking Biology News(10 mins):
(Date:11/27/2015)... Kingdom , Nov. 27, 2015 /PRNewswire/--  Mallinckrodt plc ... company, announced today that it has closed the sale ... business to Guerbet (GBT- NYSE Euronext) in a transaction ... encompassed four manufacturing facilities and a total of approximately ... in the St. Louis area. ...
(Date:11/26/2015)... , November 26, 2015 ... --> Accutest Research Laboratories, a ... Research Organization (CRO), has formed a ... Center - Temple Health for joint ... ,     (Photo: ) , ...
(Date:11/25/2015)... Nov. 25, 2015  PharmAthene, Inc. (NYSE MKT: PIP) ... a stockholder rights plan (Rights Plan) in an effort ... carryforwards (NOLs) under Section 382 of the Internal Revenue ... PharmAthene,s use of its NOLs could be substantially ... defined in Section 382 of the Code. In general, ...
(Date:11/25/2015)... HOLLISTON, Mass. , Nov. 25, 2015 ... a biotechnology company developing bioengineered organ implants for life-threatening ... will present at the LD Micro "Main Event" investor ... PT. The presentation will be webcast live and posted ... also be available at the conference for one-on-one meetings ...
Breaking Biology Technology: