By Susan Milius
To survive the thrashing of several million waves a year, a hard-bodied Pacific seaweed relies on special joints that work like loose bundles of strings.
The purply red Calliarthron cheilosporioides isn’t a soft, floppy seaweed. One of what biologists call coralline algae, it grows as branching strands of calcium-hardened segments. “If you didn’t know better, it would look like coral,” says biomechanist Mark Denny of Stanford University’s Hopkins Marine Station in Pacific Grove, Calif.
Between the hard segments lie joints of flexible connecting tissue made of long,soft, skinny cells running side by side. The joints bend as the surf whips the algae back and forth, and they can deform thousands or even millions of times before they fracture, Denny and his colleagues report September 25 in the Journal of Experimental Biology.