Age determination in fish fish. Johannes Reibisch, working for the Commission of Scientific Investigation of German Seas at Kiel, attempted to use Hoffbauer’s techniques to age plaice ("Plueronectes platessa") but found it difficult to accurately discern annuli. He decided to study a different structure and in 1899 he published the first procedures using otoliths as an aging structure. A fellow scientist also with the German Commission at Kiel, Friedriche Heincke, also frustrated with difficult scale annuli, further studied other structures to age fish. He discovered annuli in the vertebrae, opercula, and pectoral girdle and published his findings in Heicke 1905. The works of Hoffbauer,
Orange-eyed nudibranch cerata are reddish or orange with white tips. The colour of the cerata varies with diet. This nudibranch feeds on a variety of hydroids. Its egg mass is a broad coil of one or two whorls. Orange-eyed nudibranch The orange-eyed nudibranch, scientific name "Cratena capensis", is a species of sea slug, specifically an aeolid nudibranch. It is a marine gastropod mollusc in the family Facelinidae. This species has only been found around the South African coast from Saldanha Bay to Port Alfred, intertidally to at least 30 m. It is endemic to South Africa. The orange-eyed nudibranch grows to between