Publication details
Orientace mezi mořem a souší. Antarktičtí blešivci používají magnetický kompas
| Title in English | Sea-land orientation. Antarctic gammaridae do use magnetic compass. |
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| Authors | |
| Year of publication | 2013 |
| Type | Conference abstract |
| MU Faculty or unit | |
| Citation | |
| Description | For small animals living in the littoral zone of the sea, it is vitally important to orient in the changing environment of the cost line, where there is a danger of flushing away or beaching during high and low tide changes. There is not enough reliable spatial guidance inside the waves close to the shore, but ubiquitous and constant magnetic field of the Earth is present even here. . We were wondering whether gammarids living abundantly in the waters along the coast of Antarctica are able to use magnetic compass sense. Within the program of polar research of Masaryk University, we examined the spontaneous orientation of gammarids (Gammarus sp.) which were caught in the littoral zone of the beach close to the station of J.G. Mendel on James Ross Island. Our hypothesis assumed spontaneous orientation along the axis sea-land i.e. perpendicular to the coastline. After being caught in the water near the shore, individuals were transferred to controlled laboratory conditions. They were individually released from the centre of a circular arena (a bowl with diameter 24 cm and homogeneously illuminated) filled with seawater. Using the video record we determined the angle between the North – South axis and the axis of animal movement from the centre to the point of first contact with the edge of the bowl. The direction of movement was evaluated blindly – the evaluating person didn’t know which group of animals was involved. In natural magnetic field, we found that gammarids spontaneously orient at an angle of 61 (n = 40, p 0,01), which corresponds with the direction towards the sea reflecting the position of the home beach. We verified magnetic base of the orientation by rotating magnetic North. After the rotation of a field at an angle of +60, the direction of movement has changed adequately from 61 to 107(n=41, p=0,0467). Similarly, after rotation the angle by– 60 with respect to the natural magnetic field the preferred direction of gammarids preferred an angle 327 (n=51, p=0,0395). Limited time available and the bad weather conditions didn’t allow the verification of the spontaneous navigation animals from differently oriented beach. Our preliminary results confirmed that gammarids of the genus Gammarus spontaneously orient towards the sea and the geomagnetic field provides them with important guidance during their active movement in the littoral tidal zone. The authors wish to thank the Czech Antarctic Station J.G.Mendel on James Ross Island, supported by the Czech Ministry of Education. |