Re: NANFA-- Are lampreys fishes?

Dave Neely (rheopresbe_at_hotmail.com)
Wed, 12 Jan 2000 11:50:58 CST

The most logical way to look at the diversity of life on Earth is in the
framework of a phylogenetic classification. The term "fishes" as is
generally used, includes members of several different independent lineages,
and not all of the descendents of some lineages. In "phylospeak", such a
group is called paraphyletic (or a grade). Another groups like this is the
"Reptilia."

Why is this bad? A classification scheme should try to maximize information
content. Recognizing unnatural groups (grades or paraphyletic groups)
reduces the amount of information in the classification. As an example,
Linnaeus erected a group <Vermes>, in which he put long, skinny things like
snakes, eels, worms, etc. Hopefully the logical error here is obvious to
everyone. The recognition of a formal group called "fishes" is amost as
blatant an error.

>You must also remember that the term "fish" in itself has no >phylogenetic
>meaning. Lampreys are as different from sharks and true >fishes as they are
>from humans. Heck, even lungfishes are more >closely related to mammals
>than they are to other fishes.

Unfortunately, this isn't often the way it is presented in the school
systems. It also isn't the way the general public views these critters.
Therein lies the real tragedy.

>They [lampreys] are too cool to give to anyone else!

Very much agreed.

cheers,
Dave

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