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A similar form of aggregating was also observed in salmon sharks (Lamna ditropis) gathered off the coast of Alaska, waiting for the salmon migration (Hulbert et al., 2005). The salmon sharks switched between focal foraging and foraging dispersal strategies as they hunted, but they never cooperatively hunted for salmon as a group. Thus it appears there is no affiliation between hunting strategies and size segregation in sharks; the only social factor observed were warning displays (Klimley et al., 2001).

Protection

Although sharks do not segregate into groups of cooperative hunters, it’s plausible that they might segregate themselves into groups of homogeneously sized individuals in order to protect themselves (Guttridge et al. 2009).

Since sharks aggregate due to overlapping dietary resources (Wetherbee&Cortes, 2004), it’s no surprise that pregnant leopard sharks ( Triakis semifasciata ) aggregate in Humboldt Bay, California in order to give birth in clumps of eelgrass (Ebert&Ebert, 2005). The eelgrass is abundant with fish eggs, an important food source for newborn juveniles (Ebert&Ebert, 2005). In a similar manner, bluntnose sevengill sharks ( N. cepediamus ) enter the bay to birth their young after other elasmobranches have left. Just like how the juvenile T. semifasciata feed on fish eggs in the eelgrass, newborn bluntnose sevengill sharks feed on other newborn elasmobranches, especially juvenile leopard sharks.

However, Heupel and Heuter were astonished to find, in 2002, that juvenile blacktip sharks ( Carcharhinus limbatus ), despite living in the nutrient rich nursery, aggregate in the northern end of the bay rather than in the center where the prey is densest. According to the behavioral patterns observed in other elasmobranches, the juveniles should have aggregated where the food was most abundant. Instead, for the first 6 months after birth, the juveniles concentrated themselves in the kernel, the area in the northern end of the nursery (Heupel et al, 2004). A more indepth study of juvenile blacktip sharks by Heupel and Simpfendorfer in 2005 revealed that the young C. limbatus were observed to make daily foraging trips into the midst of where prey was densest; however, instead of remaining there, they return to the northern end of the nursery. The repeated behavior indicates that there must be a direct fitness benefit involved with such behavior. The occasional larger elasmobranch in the prey-rich area of the nursery may be the source of such a behavior (Heupel&Simpfendorfer, 2005). In gathering together away from areas of high prey density and areas containing possible predators in large, they use increase their survival rate. Thus despite the fact that protective segregation only applies to juvenile elasmobranches, the behavior observed indicate that sharks do in fact gather in order to protect themselves.

A chart showing interaction time between sharks A bar graph showing shark interactions  within various population sizes.
Right As can seen from the amount of time spent with the different groups of sharks, the different ages have differential preference for those their own age and size. Left As seen with the bar graphs, the sharks preferred to spend more time with other sharks than to be solitary: the more sharks there are in one area, the more time spent with the sharks.
Both graphs are reproduced from Guttridge et al.'s (2009) data

Questions & Answers

Do somebody tell me a best nano engineering book for beginners?
s. Reply
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Devang Reply
are you nano engineer ?
s.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
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SUYASH Reply
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SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
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Cied
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Damian Reply
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Cied
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
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Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
AMJAD
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
AMJAD
what is system testing
AMJAD
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
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Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
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Smarajit Reply
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Source:  OpenStax, Mockingbird tales: readings in animal behavior. OpenStax CNX. Jan 12, 2011 Download for free at http://cnx.org/content/col11211/1.5
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