Hidden Britain
REVEALS A FASCINATING WORLD OF WILDLIFE THAT WE OFTEN OVERLOOK.
Nick Baker on a fish with a big head and ‘piggy’ eyes
When I want to spot something I’ve never seen before, or simply meet something very weird, I head for the coast. The shores of the British Isles offer rich pickings for the naturalist, especially at this time of the year.
One of my favourite coastal creatures that I’ve stumbled upon requires more than a cursory glance to appreciate its true lugubrious splendour. Go rockpooling at the very lowest of the low spring tides and you’ll increase your chances of meeting Montagu’s sea snail, Liparis montagui. The first thing you need to know is that it isn’t a mollusc, but a fish in the snailfish family, Liparididae.
All the snailfish are pretty strange, though I have a particular fondness for Montagu’s. Not only is it the species you’re most likely to encounter, as it lives in the intertidal zone of rocky shores around most of our coastline, but when I hunt for it I also like to imagine the delight of its discoverer, Colonel George Montagu, when he saw it for the first time.
You need to search through the Laminaria zone, where brown leathery fronds of kelp grow on the rocks. It’s a difficult place to explore, which probably explains why it is often ignored in favour of pools higher up the shore.
Persevere and take your time, parting and flipping over the slippery weed, looking carefully under stones and around the kelp holdfasts. You will find plenty of mysterious creatures, but when your eyes finally fix on your first snailfish you’ll do a double-take. It’s about as far from a ‘fishy’ fish as you can get – like an amorphous, partially sucked wine gum that has been spat out. This tiny dollop of sub-marine life – a brown, pinkish, yellow or slightly mucky orange blob – blends in well among the crustose algae-covered rocks and spidery kelp holdfasts. Moreover, it is scaleless, reminiscent in its slipperiness of an amphibian tadpole. And small too: a big one measures about 5cm long, were you to stretch it out.
BIG-HEADED
Like a cat on the hearth, this strange fish is often found resting in a distinctive curled-up posture, with its tiny, tapering tail beside its head. In fact, the bulbous head seems to make up u the bulk of its body. Look closer c and you’ll notice a pair of very v small ‘piggy’ eyes, above a wide w mouth lined with small, crustacean c crushing teeth.
To get a better look, transfer th he fish to a clear-sided vessel. Here H it’ll reveal why it was so tr ricky to dislodge. It will stick to th he side or bottom with a sucker d disc, or PSO (pelvic suctorial o organ), a beautiful thing with r ribs and bony plates radiating fr from its centre, hinting at the h highly modified pelvic fins from which w the sucker is derived. The T suctorial organ helps this fish fi to stay in place against the pounding p ocean waves.
But how does the sucker work w on uneven, variable rock surfaces? s Partly, this is by in ncreasing the volume of the cavity c in the sucker itself (much li ike suckers on a bath mat). But th he fish is also thought to employ h hair-like bumps on the edges of th he sucker to form a seal with the uneven u rocks, and to maximise th he tiny molecular ‘Van der Waals’ W forces. In addition, the secretion s of viscous mucous acts li ike glue, generating something called c Stefan adhesion. All highly effective, e as becomes apparent if f you try to persuade the fish to return r to where you found it.