Progression into the sand coincides with
large pressure pulses and is facilitated by the
secretion of a large amount of mucus. Contrary
to popular belief, the lingula pedicle
is not used for burrowing; it is unable to dig
into the sediment. Instead it acts as a support
or prop while repeated scissor like movements,
shell closure with water injection, and
shell openings accompanied by pressure
pulses result in successively deeper penetration.
Burrowing follows a semicircular
course, the radius of which probably depends
on shell size. The animal burrows obliquely
downward to a depth that has not yet
been established in natural conditions, then
curves upward and burrows vertically until it
reaches the surface of the sediment. Pedicle
anchoring following burial is achieved by
mucoid adhesion of sand and various particles.
Some fossil U-shaped burrows could
be related to re burrowing features (EMIG &
others, 1978). While reentering the sediment
the animal is extremely susceptible to
predation.