Hecht, T

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SHORT COMMUNICATIONS A NOTE ON PHOTOGRAPHING OTOLITHS T HECHT Deptmmem of Zoology. Un;\'efsi,y of PorI Elizabelh A<xepted: April 1977 The sagiu..al otolit hs of rlShes have in recent years become importanttuonomic aids. Forthis purpose high quality photographs have become esse ntial to illustrate such fine: structures as the crislae and the colliculi which art often useful in distinguishing between closely related species. The method described bdow proved to be suc::cc:ssful in illustrating these features. The ends of a glass tube (d=5 mm)ca. l6cm long are heat-bent at right angles to form two arms approximately) cm long. Approximately I g of ammonium ch loride(N H.CI) crystals is put into the glass tube and I'Ieated with a bunsen flame from below. NH.Q has the property of changing from the solid to the gaseous state on heating. When a gaseous vapour becomes evident in the glass tube the flame is moved to one of the open ends of the tube and the other end is placed over the otolith. As it cools on the otol ith the gas instantaneously returns to the solid state in the form of a thin white powdery layer. Care must be exercised to obtain a thin evenly distributed layer over the otolith. This thin white layer has the property of acetntuating the important fea tures on the otolit h surface. Moreover, it renders the otolith opaque, which is an added adva ntage for photography. After photographing the otolith the NH.Cl film may be removed by rubbing wi th the fingers. Figure I iUuslrates the advantages of th is method of preparation. FICURE I Sagilr.al otoliths of Mu/urrius rop",j;s not \luted (lefl) and HUled (rlghl) with /'i H,CI. Zo%rieo Ajricono /}(2): 497- 508 (1977) Reproduced by Sabinet Gateway under licence granted by the Publisher (dated 2010). 

A note on photographing otoliths

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A note on photographing otoliths

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