Dolphins and Whales - why do they strand themselves?
Wednesday 14th November 2007
Why do dolphins and whales beach themselves?
Before now this has been an unexplained mystery, and one marine biologists have completely drawn blanks over. But the answer may lie in the geomagnetic forces of the moon.
An electric generator consists of a magnet and a loop of wire which rotates in the magnetic field of the magnet. As the wire rotates in the magnetic field, the changing strength of the magnetic field through the wire produces a force which drives the electric charges around the wire. The force initially generates an electric current in one direction along the wire. Then as the loop rotates through 180 degrees the force reverses to give an electric current in the opposite direction along the wire. Every time the loop rotates through 180 degrees the direction of the force and therefore the current changes. The changing direction of the force after every 180 degrees of rotation gives the alternating current. As well as having the magnet and wire an electric generator also has slip-rings which make sure that the ends of the wire are always connected to the same side of the electric circuit. This makes sure that the direction of the current changes every half revolution of the wire.
The force that produces the current in the wire varies as the loop of wire rotates through the magetic field. The force is given a special name, it is called the "electromotive force" or e.m.f. It is similar to the potential difference that gives the flow of electrons in dc currents and is also measured in Volts.
Now consider what happens to the current in the loop of wire as the wire rotates through the magnetic field. First the loop of wire is moving parallel to the magnetic field. When the wire is moving parallel to the field there is no emf or electrical current. As the loop rotates the bottom end moves up and the movement of the loop is now at an angle to the magnetic field. When the movement of the loop is at an angle to the magnetic field an e.m.f. is produced and an electrical current flows through the loop. As the loop moves it becomes aligned with the magnetic field and the movement of the loop is now perpendicular to the field. At this point the emf becomes its largest and the current is its strongest. As the loop continues to rotate in the clockwise direction the movement becomes more aligned with the field and the emf and current gets smaller. When the loop is again in the vertical position the direction of rotation is aligned with the magnetic field and the emf and current drops to zero. The loop has rotated through 180 degrees. As the loop rotates past 180 degrees the loop is again moving at an angle to the magnetic field and a current is generated. However this time the force that creates the current points in the opposite direction since the end of the loop is moving down and not up. We now have our alternating current. The current is again its strongest when the loop is parallel to the field and the rotation is perpendicular. As the loop rotates back to and through the starting position the current again drops to zero and reverses direction. This process continues while the loop continues to rotates and only stops when the loop becomes stationary. The faster the loop rotates the larger the force on the electric charges and the larger the electric current.
The Moon crosses the magnetic field of Earth twice per month as part of the declination cycle of 27.3 days. In effect the Moon is part of a giant dynamo angular-transiting Earth's equator whilst at the same time changing longitude. The angular speed when crossing the equator is about 6deg per day but when at the peaks (N or S declination) only 1 or 2deg per day. The moon is also moving in a horizontal plane around the polar axis at an average of 13deg per day, speeding to about 16deg during perigee, a device that may mimic slip rings in producing an electromagnetic current discernible to land, sea and air creatures. At the moment (19 December) the Moon is crossing the equator heading north, the lunar equinox. At this midpoint the maximum charge results because the Earth's field is being crossed more quickly. Remember that when the wire is moving parallel to the field there is temporarily little or no emf or electrical current, and such would be the case at declinations, N and S.
It is conceivable that dolphins and whales use sonar systems to navigate, beamed toward the Moon which provides them with a geomagnetic map, such that the creatures know where they have been and how far they have traversed in recent days and weeks and hours. It is also conceivable that in the lunar declination cycle at N or S declination this signal from the Moon is at its weakest, if not stopping altogether. It is further conceivable that when the creatures find themselves at or near areas rich in iron sands a latent signal emanating from the sands may be received which may fool the creatures' into thinking that the beach is in fact the open sea. Or it may be that at declinations N and S the creatures are just navigationally inactive and are either themselves swept along by strong tides or are following shoals of fish that are swept along by strong tides. It is already known that Fin whales seek out areas of low magnetic-field intensity during the fall and winter. Stranded pilot whales are found most often where areas of low magnetic-field intensity intersect with coastlines.
There is another factor. In AC circuits, it is possible that the potential difference (PD) across a device and the current going through a device are either in or out of phase. In layman's terms, although the PD and current have the same period, they do not reach their maximum or minimum at the same time and are out of `sync'. Either the current or the PD can be ahead and lead or behind and follow, it all depends on the device's and the circuit's configuration. Imagine if two current-producing mechanisms both occur in the same device, making for two current-curves, which we might imagine are the superimposed diagrammatically one over the other. We may consider the sine curve of the lunar declination overlapping the sine curve of perigee/apogee cycle. Peaks at N and S declination coinciding with peaks in perigee/apogee may produce magnetic field troughs.
Another consideration is that around NDs, SDs, apogees and perigees we get more earthquakes and undersea eruptions. Could it be that the shock and pressure waves, even loud booms underwater, might give these animals shock and temporarily disable their navigational systems, allowing the tides to carry them in? This explanation seems very likely, as strandings occur around new and full moons, perigees/apogees and declination peaks, all of which are earthquake risk times, making strandings above-water signs of local underwater earthquake activity. Add to that the topography of the undersea environment around NZ, as described in http://www.stuff.co.nz/stuff/0,2106,3523439a6013,00.html
which comprises deep trenches and canyons amplifying shock waves of any creatures trapped within the canyons' walls. Of course whales and dolphins would inhabit these places as they would be chasing fish. The recent strandings in Takaka would be thus explained.
When lunar peak/troughs of interlocking cycles such as new moon/declination/perigee have occurred, mass beachings have resulted on cue. It is unclear whether the mammals beach every time the moon is in position or if when they beach the moon is in that position. For purposes of this discussion a mass event is defined as 3 or more individuals arriving seemingly together. For instance, in November 2004 such lunar-peak times occurred on November 5, 15 and 29th and in December on 13th and 26th. For November and December these dates have also been times of dolphin strandings. I now have statistics from DOC going right back to 1902 that verify the trend. Based on data gathered so far, this trend is amazingly consistent and encouraging far beyond the realm of coincidence. If anybody involved in marine research reads this and wishes to add ideas, alternative viewpoints or dates of beaching timings here, please contact me on enquiries@predictweather.com
The next dates likely to see more mass strandings:
January 13, 2006(northern declination)
January 23, 2005(northern declination)
on the 23rd there were many shark sightings in Auckland. 200-300 hammerhead sharks were seen on the North Shore where usually there are none, and large adults were near the shore which was stated to be quite uncharacteristic. If there are environmental factors involved for strange whale and dolphin behaviour they may also apply to sharks.
February 6, 19
on around the 19th a pod beached on Waikuku Beach, Northland, and were discovered ten days later.
On Nov 9, 2006, day of the N dec, 37 whales stranded on Ruakaka