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Overflowing with nonsense

Conservapedia is an online “encyclopedia” dedicated to distributing consie “knowledge” (read: nonsense) and they are quite the jokesters. Going through the website at random, I stumbled on their article on Chordata. I have never seen any article in any self-proclaimed encyclopedia with nearly every sentence having something incorrect in it. A debunking follows.

The article in its current version has ten paragraphs (counting each member of the bulleted list seperately). Each paragraph has one sentence. The numbers in the following indicate the paragraph I am debunking. Bold italics is a direct quotation, and plain text is what I say.

1: Chordata is a phylum of animals, named after their common feature – possession of a spinal cord. Chordata is indeed an animal phylum. But only vertebrates have a spinal column; the proper term is a dorsal nerve chord, and all chordates have that at some stage in their life. And in addition, other common features include, at some stage of development a post-anal tail, slits in the pharynx, and a flexible dorsal rod called a notochord.

2: Yes, there are indeed several classes in Chordata. But there are also three subphyla, Urochorda (tunicates), Cephalochordata (lancelets), and Vertebrata (vertebrates).

3: Mammalia is a class containing mammals.

4: Aves is a class containing birds.

5: Reptilia is a class containing reptiles. Strictly speaking, the word reptile refers to a paraphyletic (a group of animals containing a common ancestor but not all of its descendants) group of amniotes (animals with an amniotic egg) that are not birds and not mammals.

6: Amphibia is a class, although as reptiles evolved from it it is paraphyletic.

7: There is no class called Pisces. Instead, there are several classes of fish: Agnatha (lampreys and hagfish; sometimes hagfish are considered not to be vertebrates and given their own clade  called Myxini). Acanthodii (spiny fish that went extinct in the Permian); Placodermi (heavily-armoured fish that went extinct in the Devonian); Chrondrichthyes (cartilegenous fish such as sharks, rays, and chimeras); Actinopterygii (ray-finned fish, including everything from gars to gobies); and Sarcopterygii (lobe-finned fish such as lungfish and the coelecanth).

8: While lancelets and hagfish are indeed chordates, acorn worms are usually given their own phylum, Hemichordata. That phylum also includes graptolites.

9: In vertebrates, one end of the nerve chord is enlarged into a brain, but otherwise the common features are the ones I mentioned above.

10: Scientists believe that the chordata are closest to the arthropoda (shelled, joint-legged animals such as insects and crustaceans) and annelida (earthworms) in biology, due to common features such as segmentation, which are not seen in other phyla such as the mollusca (molluscs) or coelenterata jellyfish and sea anemones. Completely wrong. The closest relatives of Chordates are other deuterostomes (animals where the blastopore develops into the anus). Besides acorn worms, this includes echinoderms (starfish, sea cucumbers, etc) and the enigmatic Xenoturbella. Arthropods, and annelids are not close relatives of deuterostomes nor of each other. Also, the phylum containing jellyfish and sea anemones is called Cnidaria.

Source for the above information: UCMP page on Deuterostomes and the pages on its subtaxa.


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