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,
Pinnoctopus cordiformis appear to be consistent differences between specimens identified as "P. cordiformis" and those identified as "O. maorum" which suggests that there is a second species but this species more closely resembles a species of the genus "Enteroctopus", with the description closely resembling "Enteroctopus zealandicus". The name "the name Pinnoctopus cordiformis" is regarded as unresolved, a "nomen dubium", by some authorities. Pinnoctopus cordiformis Pinnoctopus cordiformis is a species of octopus found around the coasts of New Zealand. "Pinnoctopus cordiformis" is identifiable by their orange-brown or purple-grey colouration; iridescent white spots are also found on the arms and web. No white spots