Was It Designed?

The Digging Skill of the Razor Clam

● Although it appears to lack sufficient strength to dig through sand, the razor clam burrows into hard-packed ground so quickly that it has been called “the Ferrari of underwater diggers.” Researchers were intrigued. “We knew they were doing something tricky,” says Anette Hosoi, an associate professor at the Massachusetts Institute of Technology. What is the razor clam’s secret?

Consider: The razor clam wiggles its foot down into the sand, creating a small pocket that quickly fills with water and sand. The clam then moves its body up and down while opening and closing its shell. This results in a watery mixture that the clam can easily dig through. The razor clam can dig some 28 inches [70 cm] at a speed of 0.4 inch [1 cm] per second. Once dug in, the clam is hard to pull out. In fact, considering its anchoring force and the amount of energy it uses to embed itself, the clam is ten times more efficient than the best anchors made by man.

Engineers have been inspired by the razor clam in designing what they call the first “smart” anchor. “It opens and closes, and moves up and down, like a real clam,” says Hosoi. Such a strong, energy-efficient anchor could be useful on underwater research vessels, floating oil rigs, and digging devices that destroy mines.

What do you think? Did the razor clam’s digging skill come about by chance? Or was it designed?

[Pictures on page 23]

This prototype of a “smart” anchor mimics the burrowing technique of the razor clam

[Credit Lines]

Razor clams: © Philippe Clement/​naturepl.com; “smart” anchor: Courtesy of Donna Coveney, Massachusetts Institute of Technology