Hunkered down among seaweed, this‘ decorated’ spiny spider crab would become near invisible
A deep-snouted pipefish has the perfect shape to match seagrass, only the camera’ s lights make this one obvious
crab or mud-runner – the males have claws up to five times as long as their carapace. A signal can also just tell a predator it’ s been seen and noted, so it’ s best for them to go elsewhere, such as in the two arms-up‘ V’ display by cuttlefish.
Cuttlefish display two raised arms to tell a predator that it is being watched, so an attack will be fruitless
Entangling your attacker with extruded but replaceable internal organs may seem a particularly extreme approach, but that’ s exactly what the cotton-spinner sea cucumber does, giving rise to its name.
Fish shoals or schools, the latter term
meaning where the fish are tightly coordinated, are the classic case of a safety in numbers strategy. As well as other benefits such as improving swimming efficiency, a close grouping confuses predators and reduces danger, especially for individuals in the centre, hence the way the fish bunch up as a threat approaches. Shoals and schools are sometimes defined as being of a single species, but fellow travellers don’ t have to be the same as you to provide protection. I was intrigued recently to see Atlantic horse mackerel and seabream( probably blackspot) shoaling together in Plymouth Sound, but I gather from fish experts that mixed shoals of various species are quite common.
From octopuses building dens and squirting ink clouds to sea slugs recycling weapons from their food, our marine animals keep out of the clutch of predators in a vast variety of ways and I have barely skimmed the surface. What will you observe on your next dive? �
Paul’ s photos and video clips capturing UK marine life stories are on Instagram @ paulnaylormarinephoto
Look how big I am! A male angular crab spreads his ultra-long claws
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