How to Tell the Age of an Octopus (no, really!) There are several ways of determining the age of a variety of living and non-living organisms. We can count the rings in a tree and most animals can be judged based on size, body shape, and teeth. Even rocks have radiocarbon decay to tell their age. But what about our friend the octopus? How can we tell their age? Its actually a serious question. When keeping track of an organisms numbers or determining reproductive rates, age is an important factor in studying population. A scientist that works in a fishery can determine the age of fish populations by studying their otoliths. An otolith is a hard calcium deposit and is also known as an ear stone. The otoliths acquire rings of calcium deposits based on different rates of growth over various seasons. These calcium deposit rings can be counted (similar to the rings on a tree) to give an estimate of a fishs age. But the octopus does not possess such a feature. They are almost completely soft-bodied with no bones or ear stones and no, counting the rings doesnt really work. Up until recently, researchers studying the octopus have primarily relied on using size to estimate age. This is problematic however because body size can vary widely based on food availability, water temperature, and other factors even within the same species! A group of researchers in Mexico have published a new paper that suggests there may be a reliable way to figure out the age of one common species of octopus: the local Octopus maya. The group raised 32 octopuses in captivity and studied their beaks, stylets, and eye lenses (all made of harder material) at different ages. The study results indicated the eye lens did not predictably show any particular growth pattern. The octopus beaks, when sliced through, showed a somewhat reliable predictor of age in days when they were younger, but the reliability degraded as the octopuses got older. The stylet, however, seemed to be a good indicator. The stylet is a hard component that resides in the mantel (head area) of the octopus. The researchers noted that measurements here were closely related to age in days. These findings will be released in the November issue of the Journal of Experimental Marine Biology and Ecology. There is also a link to a journal article at the end. The news of measuring the stylet of an octopus to determine its age has been suggested before in another common species - Octopus vulgaris. Currently, as the stylet resides in the mantle of the octopus, these measurements can only be taken postmortem. As more information is discovered, this data will be a useful stepping stone in the search for less invasive methods to determine age. What makes this particular study unique and of interest is the choice of species (Octopus maya) is common in aquaculture farming, thus lending valuable information in keeping track of population numbers and age ranges. (Im a sucker for cephalopods. It had to be said.) ~Ashley Source: blogs.scientificamerican/octopus-chronicles/2013/10/30/hey-how-old-is-that-octopus/ Journal Article: sciencedirect/science/article/pii/S0022098113003407
Posted on: Wed, 06 Nov 2013 23:41:48 +0000
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