![octopus eyes octopus eyes](https://thumbs.dreamstime.com/z/big-octopus-eyes-lot-tentacles-illustration-226061061.jpg)
100 and 400, and with metal polisher as a final step. Thin sections were polished manually with wet sandpaper nos. The lenses were dehydrated with the same technique recommended for paraffin inclusion, with five more baths to induce the penetration of the plastic solvent and the plastic resin ( Table 3). Plastic inclusion with polished thin sections was tried as an alternative to microtome sectioning. Sections were stained with Harry's hematoxylin-eosin stain ( Luna 1969). For microscopic analysis, they were treated with decalcifying solution ( Table 1) prior to dehydration and paraffin inclusion ( Table 2). After fixation in neutral formalin ( Luna 1969), the lenses were measured in diameter with vernier calipers and weighed with a digital plate scale with 0.01-g precision. The organisms were measured and weighed fresh, and their eye lenses fixed. megalocyathus were subsampled from a monthly sample of the commercial catch of a fisheries population from the ports of Queilen and Ancud, Chiloe, Chile, carried out by the Instituto de Fomento Pesquero (IFOP). Two hundred twenty-eight individuals of E. We also present a technique to observe the structure of octopus lenses under light microscopy, discussing its potential for age determination. megalocyathus eye lens weight and diameter to its mantle length, total length, and weight. The aim of this contribution is to present a technique to visualize the eye lens structure and to evaluate its application as a tool for age determination in E. Although the technique for preparing and reading stylets has improved, its application to Enteroctopus megalocyathus has not given satisfactory age readings during our investigations, with age underestimated. 1994, Raya & HernándezGarcía 1998, Perles-Raya et al. The beak, statoliths, and stylets have been proposed as structures where daily growth marks are registered ( Raya et al. The lack of hard structures in the body of an octopus has prevented the determination of age. It has been used in cephalopods with reservation ( Guerra 1979, Nepita & Defeo 2001), because they have short life spans of 1 or 2 y, and recruitment extends for several months, with a wide variation of sizes even from a single parent ( Cortez et al. 1993), a technique that works for populations with a clearly defined recruitment and with a life span of several years ( Allen 1966, Jones 1981).
![octopus eyes octopus eyes](https://c8.alamy.com/comp/AA28R0/kk2515-pacific-giant-octopus-enteroctopus-dofleini-pacific-northwest-AA28R0.jpg)
Therefore, population size structure has been used as an alternative method ( Gayalino et al. Lens diameter and weight showed a much smaller variation than body length or weight, with an apparent correspondence of size or weight classes of body measurements to a lens diameter or weight.Īge determination of soft-body organisms has always been a major problem for fishery biologists ( Tesch 1971). The lines start to form in the prehatching larvae. The prehatching nucleus was identified, and the total number of lines counted. They were measured, weighed, and prepared for histological analysis of the concentric lines structure.
![octopus eyes octopus eyes](https://images.fineartamerica.com/images-medium-large-5/octopus-eye-greg-ochocki.jpg)
The lenses of 228 octopi were obtained from the commercial catch from Ancud and Quellén, in Chiloe, Chile. Given the structural similarity of lenses between octopus and vertebrate, we explore the possibility of using octopus eye lens weight, diameter, and structural marks as age indicators. Eye weight, pigment, and nitrogen content have been used successfully in age determination of vertebrates. So far, none of these structures have proved reliable or practical for the purpose. The need for age determination for the proper management of octopus fisheries has directed research attention to the few hard structures in the octopod's soft body, beak, statoliths, and the vestigial shell.