HORNETS glue tiny magnetic crystals into the roofs of the hexagonal cells
that they build for brood-rearing, biologists have found.
Jacob Ishay of Tel Aviv University in Israel and his colleagues at the
University of Groningen in the Netherlands found fine fibre 鈥渧eins鈥� that
gathered at the centre of the cell roofs.
鈥淲e thought there must be something connecting these fibres in the middle,鈥�
says Ishay. When they looked closer, they found each cell roof contained a
crystal of magnetic iron titanium oxide measuring a tenth of a millimetre
across.
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鈥淭hese tiny crystals form a network that may act like a surveyor鈥檚 spirit
level, helping the hornets to assess the symmetry and balance of the cells,鈥�
says Ishay. The crystals, glued in place with saliva, could be secreted by the
hornets or collected from soil, he says.