The male bullhead
closely guards
his clutch of eggs
against predators.April 2020 BBC Wildlife 21WILD APRIL
treasure: a mass of up to 400
yellowish-white eggs, which
meant he’d managed to woo a
female. How the male bullhead
goes about this is yet another
wonderful surprise.
To entice a female to his love
lair, the male ‘sings’ – maybe
not quite as tunefully as that
word suggests, but impressive,
nonetheless. By rubbing the
bones of his pectoral girdle
against those of his skull, the
fish delivers effective pulses
of sound in the 50–500Hz
range – anywhere between
four and six of them. He can
even hit notes up to 3kHz.
This dull thudding sound
seems to penetrate the higher
frequency background noise
of a stream or river’s acoustic
landscape. It has the effect
of luring a female, who we
can only assume recognises
qualities in our male that she
alone can perceive. Female
bullheads will also sing, but
to a lesser extent.
If the pairing is successful,
the female lays eggs under the
male’s stone. After fertilisation,
he’ll sit by and guard the eggs
against predation. Patiently he
fans the clutch, keeping it clear
of sediment and ensuring a
plentifulsupplyofoxygen.Iustrat
ons
by
Peter
Dav
dScott/The
Art
Agency
NICK BAKER
is a naturalist, author and TV presenter.Revealsafascinating
world of wildlife that
we o en overlook.Despite being small in size,
thebullhead makes up for it
inecological impact, being an
incredibly important food fish.
Itsmanypredators include
trout,salmon, kingfishers,
heronsand otters (even,
historically, humans).Lovesongs
Atthistime of the year,
throughto mid-summer,
loveis inthe water. A frisky
malebullhead setting up
his territory becomes
much darker and
his first dorsal fin
develops creamy
white edging. He
is now in full battle
dress – a livery to
match his mood –
and aggressively
defends his little patch
of stream or riverbed. The
fulcrum of all this activity is
almost always a rock large
enough to be his fortress.
I still vividly recall the
child’s thrill of gently lifting
fist-sized stones in a stream,
then waiting with bated breath
as the swirl of displaced silt and
sediment settled down, to see
if the clearing water revealed
a bullhead glaring back at me
with indignation. If I was even
luckier, the underside of his
rock would be plastered withW
e don’ttendto
celebratefish
unlessthey’re
edibleorbig
andspectacular.Thebullhead
(AKAmiller’sthumbortommy
logge)is,atfirstglance,the
veryantithesisofthis.It’sa
smallandunobtrusivefishof
streams,riversandlakes,not
much bigger than a human
digit when adult. Yet, however
diminutive it may be, the
bullhead is full of surprises.
First up, it is a member
of the sculpin family, most
of which are actually marine
fish. Look at a long-spined sea
scorpion – a common rockpool
fish – and you’ll immediately
see the family resemblance.
There is the knobbly head
taking up more than 25 per
cent of the fish’s 7–9cm length;
bulging eyes mounted high
up and a pair of big, flounced,
wing-like pectoral fins.
In common with its cousins,
the bullhead doesn’t have a
swimbladder. Therefore, it is a
‘benthic’ beast – that is, it lives
at the bottom of a body of water.
The species is superbly cryptic,
too. A mottled palette of browns
and blacks helps it to blend in
amid pebbles and rocks.NICK
BAKER
N
Hidden
SINGING FISH
Fish are more vocal than you might think...
Bullheads are far from unique in
their sonic talents – worldwide,
many fish communicate
with sound. Gurnards
strum muscles
against their
swimbladders
to produce
a variety of
grunts, pops
and croaks –
especially whencompeting for food. The Atlantic
herring makes a loud ticking
noise, thought to help keep
its large shoals in
formation. It does
this by emitting
bubbles from
its anus. This
non-digestive air
release is known
an FRT (fast
repetitive tick).Bullheads use their
large, spiny pectoral
fins to grip stones
and gravel in fast-
flowing water.D I D Y O U
KNOW?BULLHEAD