Page 11 - BBC Wildlife - August 2017 UK
P. 11
WILD AUGUST
Hidden
hould you be besidethe
seasidethis summer, there
Sis always plenty to engage
the curious naturalist’s mind.
For example, have you ever
wondered what makes those
roundedholes in submerged NICK
clay, rock and wood?These
perfect perforations are BAKER
sometimes large enough to REVEALS A
stick your little finger into. Piddocks are living
tunnelling machines.
The holes could bethe FASCINATING Only when submerged
handiwork of a number of WORLD OF by the tide do their
boring molluscs, which, despite WILDLIFE THAT siphons protrude.
their name, are far from dull.
One of the biggest and most WE OFTEN
common is the boring piddock, OVERLOOK. (the two halves of a bivalve fo or the muscular foot – a thick,
Pholas dactylus. Its scientific mollusc’s hinged shell), the fl exible anchor that creates
uction. Theother aperture
name means “finger lurking lines of which twist and contort s su
in a hole” and refers to the PIDDOCK S uncomfortably for those that p oints up towardsthe burrow
ntrance and is where the
creature’s elongated fleshy expect perfect symmetry in en
form when fully stretched out. their clams. The animalhas in
nhalant and exhalant siphons
If you explore at low tide or sacrificed the possession of p rotrude to filter-feed.
around the bottom of pilings or a tough, tight-sealing clam Ina live piddock,the loose
groynes, you may find burrows shell, andhas turned its ar rray of shells and plates is held
ogether by powerful muscles.
with live piddocks – the problem two valves from a to
is actually seeing them properly. DID YOU reinforced safety T hese work in unison with the
A peek with a torch may reveal KNOW ? capsule into what se errated shells, the front end
the retreating soft mass of the The boring piddock’s effectively amounts o of f which is armed with thick
owner’s paired siphons; one Latin name isshared toa drill bit. sp pikes. A combination of a
otation of the shell round its
sucks in water and food, the with 1970s Italian Occasionally, ro
ong axis, the pulling force of
other is the outflow. But the real rockbandPholas when piddocks die lo
he suction foot and outward
magic happens deep inside the dactylus. or are washed from th
clam-carved cavern. their burrows, some of pr p ressure on the burrow walls
A piddock has a fragile their secrets are revealed.Their a al llows the soft mollusc to grind,
matching pair of valves shells sometimes turn up on the r ra asp and file its way through all
strandline,however are seldom bu
ut the hardest of rocks. The
intact and unworn (they are ef ffect is to create a customised
surprisingly brittle). Rarer still tu
ube to spend its life in.
DRILLING DOWN is the discovery of acomplete Afinal mystery within their
Comb the beach to find examples of piddock handiwork. pair of shells attached at the al lready mysterious world is that
iddocks can bioluminesce. It
hinge, the flared architecture pi eems to be something they do
ustrat ons by Peter Dav d Scott/The Art Agency O As soon as O Since th ddock’s Excellent excavators fr rom their burrows on dark
sg
get,
O The older piddocks
O Piddoock holes often
s se
giving them the common name
co
ome and
the bigger they bec
occur inn clusters, as the
of ‘angel wings’.
p
assively, since a glow emanates
deeper theyb
urrow.
bu
animalss arecolonial.
he
e size
n
ights. Roman statesman Pliny
of eachp
pid
the molluscs
m
The two halves of a complete
mentions the startling effects
entrance
settle ouutof
hole
e
f the glittering blue slime
of
shell can be 15cmlong, though
same,
he
stays th
the plankton
pr
roduced as they were eaten.
usually are much smaller,
ost
it is alm
and starrt to
mo
imposs
ble for
instead, they have a fixed gape
or
committted to
predat
rsto
is
a naturalist, author and TV presenter.
at each end. One aperture is
their burrrows.
th
H
is new book ReWild is reviewed on p96.
I drill,theyy are extract sib em. and don’t fit neatly together; N ICK BAKER
August 20017 BBC Wildlife 11
