April 19, 1997

Letters

Mighty spears

My mind boggles at the muscular feats of ancient German hunters hurling the trunks of 30-year-old spruce trees at their prey ("German mine yields ancient hunting spears," SN: 3/1/97, p. 134). Did this produce the precursor to ground beef?

Gary W. Ankney
Greencastle, Pa.

No, but it may be the earliest evidence of shish kebabs. -- B. Bower

Color and crab claws

In "Crab Crackers" (SN: 2/22/97, p. 122), the author misinterpreted a point I made. Rather than saying that something "black at the water's surface [appears] very different when it's deep underwater," I called attention to the point that striking patterns of red on the pincers of claws observed at the surface would actually appear dark gray to black at depths where long-wavelength light has been fully or largely attenuated.

The point was that such patterns of intense color difference, whether black, red, or otherwise, are not easily interpreted in terms of function. For those of us who study functional morphology of crustacean exoskeletons, the recent report of a correlation between color and mechanical strength in stone crab claws suggests that other long-known color patterns in decapod crustaceans may also relate directly to mechanical attributes, rather than always reflecting some adaptive advantage in the way other animals in their habitats see them.

Darryl L. Felder
Professor of Biology
University of Southwestern Louisiana
Lafayette, La.

Not long after reading the article on stone crab shell strength, I came across this passage in Down & Dirty Birding by Joey Slinger, which admittedly claims only to be "packed with information, much of it accurate":

"Black feathers are tougher than white feathers and don't wear out so quickly, which is probably why evolution made the tips of the primaries of a great many gulls and the wood stork and the whooping crane and the American white pelican black."

Could it be that the association between black or dark pigmentation and mechanical strength goes beyond stone crabs and wood warblers?

Madeline Bodin
Andover, Vt.

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