Splashdown. (Letters).In "Sea Squirt's DNA DNA: see nucleic acid. DNA or deoxyribonucleic acid One of two types of nucleic acid (the other is RNA); a complex organic compound found in all living cells and many viruses. It is the chemical substance of genes. makes a splash" (SN: 10/19/02, p. 254), you report that "the sea squirt has the beginnings of a spinal cord spinal cord, the part of the nervous system occupying the hollow interior (vertebral canal) of the series of vertebrae that form the spinal column, technically known as the vertebral column. , making it a so-called chordate chordate Any member of the phylum Chordata, which includes the most highly evolved animals, the vertebrates, as well as the marine invertebrate cephalochordates (see amphioxus) and tunicates. ." That's the same mistake I fight against each time I teach my zoology class. What makes a sea squirt a chordate is the notochord notochord (nō`təkôrd'), in biology, supporting rod running most of the length of animals of the phylum Chordata and present at varying times in the life cycle. in the animal's larval stage. A notochord is a skeletal component, not a primitive nerve cord. J. ROGER EAGAN, QUEENSBURY, N.Y. SEND COMMUNICATIONS TO: Editor, Science News 1719 N Street, N.W., Washington, D.C. 20036 or editors@sciencenews.org All letters are subject to editing |
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