Paul Naylor looks at the defensive strategies adopted by UK marine creatures to avoid becoming someone else’ s lunch
CRITTERCONFIDENTIAL
Somersaulting to safety
In an impressive escape routine, a small netted dog whelk evades an approaching necklace shell with a series of somersaults
Paul Naylor looks at the defensive strategies adopted by UK marine creatures to avoid becoming someone else’ s lunch
Filming a necklace shell gliding across a sandy seabed last summer led to a surprising observation. It’ s something I’ ve filmed before, striving to closely capture the purposeful motion of this predatory mollusc while not stirring up the sand and spoiling the shot. This time, I noticed the necklace shell was on a collision course with a small netted dog whelk, the scavenging snail that crawls along with its distinctive food-sensing siphon held aloft.
Although necklace shells typically prey on small clams, I thought their ability to envelop and bore through another mollusc’ s shell might spell danger for the smaller snail. But, just as the necklace shell’ s outstretched skirt made contact, the netted dog whelk extended a greatly expanded foot and made several dramatic somersaults to swiftly escape any trouble before blithely continuing its journey.
Processing the clip made me think about some of the other ways that the familiar animals we watch on our dives have evolved to avoid predators. Camouflage is a very well-used method; if you can’ t be seen, you won’ t get eaten. Countless species blend in beautifully with the background by matching their colour and pattern, having appendages that resemble their surroundings or even, like‘ commando’ spider crabs,‘ decorating’ themselves with bits of the scenery.
Sometimes the whole form of an animal provides much of the effect. One of my favourites is the deep-snouted pipefish, whose profile makes it perfectly resemble a blade of seagrass. Thinking of sea scorpions and angler fish, camouflage can of course help with ambushing prey as well as avoiding being someone else’ s.
If animals are spotted by a predator, an alternative or addition to fleeing is to make themselves look as big and fearsome as possible. The defiant claws-spread posture of a velvet swimming crab is very familiar, but I think the best example is the angular
24