Friday Squid Blogging: Dissecting a Giant Squid
In Santa Barbara.
Among other dissection highlights, Hochberg pulled out plastic-like pieces, which comprised what could be best described as a backbone, as well as a translucent brownish-yellow piece of the beak, which is made of fingernail-like material. The giant squid’s anatomy features a mouth at the top of the head, which means the esophagus travels through the brain. “So you have to get very small chunks of food,” said Hochberg, “or you’ll blow your brains out.” The sharp beaks, then, are used to chomp food into tiny pieces before sending it down the esophagus, through the brain, and into the gut.
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Peter E Retep • September 19, 2008 6:53 PM
When I was a kid, I was taught Ontogeny Repeats Phylogeny, which led to many spectacular misconceptions, including the idea that embryo starts out as a lower order invertebrate, becomes a coelate like squid, repeats a gill creature stage, and slowly retraces evolution through gestation through amphibian, reptillian, to animal, and ultimately human form.
Genetic Code has now resolutely lain this false assumption to rest.
Taxanomic Speciation by structural differences may rest on a similarly slippery slope, also to be pushed over the edge by DNA realities.
(I refer to “As a taxonomist, Hochberg is hoping that this squid’s samples will shed light on whether California’s populations are the same species as the ones in Japan and others than show up as far south as Hawaii.” )
Currently speciation is decided by gene matrix (DNA code), by color phase, be behavior, and even by politics. [The Endangered Species Act’s “identifiable and distinguishable population in an identified region” which led to the spotted [recessive] feather phase of the barred owl being declared an endangered species, and, by some reports, shutting down the northwest timber industry.]
Under these criteria, sometimes a dalmation is a different species from a [Beverly Hills] chihuahua, and sometimes it’s only a breed difference.
To rely on taxonony to speciate when we have DNA testing available seems so last millenium. Just ask the tiglons and the grolars.