7 July 2009

ID in the bone

Ever inclined to make an inscription, human beings have figured out how to write their own messages in the heart of the [otolith]. By sequentially altering the temperature of the water in which salmon fry are hatched and raised, researchers can lay a distinctive “batch label” into the chemical layers of the otolith—a kind of barcode, inscribed in stone, and indelibly preserved within the maturing adult fish (a puckish early student of this technique used it to write “hi mom” in binary inside his experimental animal). Later, when these free-swimming creatures are captured at sea, each can be traced unfailingly to its hatchery of origin. Some five billion Pacific salmon have now been marked in this way, their inner qibla reconfigured to refer to their point of origin, and thus the point to which they seek return.
from The Orienting Stone


Emily said...

That is quite bizarrely wonderful, and reminds me: Pliny said some fish have a pebble in their heads; I had previously assumed that was just another of the folk beliefs that pervade his Natural History.

Off-topic, but what's that amazing creature in the new banner? At first I thought it was a nudibranch, but then I saw the cuttlefish eyes.

Caspar Henderson said...

Yes! Otoliths take a variety of amazing shapes in different species, as some photos in D. Graham Burnett's article show. We truly are in a new age when billions of fish are labeled from the inside.

Also amazing at statoliths: organelles used in gravity perception by invertebrates and plants. In ctenophores ('comb jellies') these are delicately balanced in stotocysts. See, for example, here.

The creature in the banner at the time of writing is Pfeffer's Flamboyant Cuttlefish, Metasepia pfefferi.