13 January 2014

Emperor penguins traffic jam

Photo by Kelvin Cope

Emperor penguins (Aptenodytes forsteri ) are endemic in the Antarctic and are known to breed in winter. In order to survive the cold winds, penguins huddle together without moving to create a tightly packed unit [2]. This allows them to conserve energy and maintain their body temperature [2].

Huddle movement is also observed where directional movements may originate from any huddle caused by a single penguin. This movement was even compared to a traffic jam [1]. The small forward movement by cars in traffic situations are the same with 2 cm movements of penguins within a huddle [1]. This movement causes their neighbour to move a step closer in the same direction, in the end merging small huddles with the bigger huddles [1, 2].

To know more about Emperor penguins, visit SeaLifeBase.
[1] IOP Institute of Physics (2013) Traffic jams lend insight into emperor penguin huddle. http://www.iop.org/news/13/dec/page_62141.html [Accessed 19 December 2013].

[2] Zitterbart DP, Wienecke B, Butler JP, Fabry B (2011) Coordinated Movements Prevent Jamming in an Emperor Penguin Huddle. PLoS ONE 6(6): e20260.

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18 September 2013

Connectivity of sea otters and crabs

 Photo by Ron Eby

Sea otters live in shallow waters and often in areas with kelp beds where they feed on invertebrates, i.e., sea urchins, crabs, etc. [1]. In the Aleutian archipelago down to California, it has been observed that the feeding habit of otters control herbivore populations in these areas, increasing the size and coverage of kelp and seagrass beds [1,2]. 

Seagrass recovery in the Elkhourn Slough, California, in spite of the degradation caused by excessive nutrients dumping, amazed University of California Santa Cruz researchers. A recent study from this group of researchers showed that interactions between sea otters and their prey is crucial in the recovery of its habitat. Sea otters feed on crabs, which feed on slugs and other invertebrates found on seagrass leaf blades. Predation by sea otters on crabs controls the latter’s effect on the population of slugs, which are important in maintaining the health of the seagrass population [2].

To know more about sea otters, visit SeaLifeBase.

[1] Estes, J.A.; Palmisano, J.F. (1974) Sea otters: their role in structuring nearshore communities. Science 185(4156):1058-1060.
[2] Stephens, T. (2013) Sea otters promote recovery of seagrass beds. http://news.ucsc.edu/2013/08/sea-otters-seagrass.html [Accessed 05/09/2013].

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