Eye opener

Mind-blowing images from Earth and beyond.

FALSE BAY, SOUTH AFRICA

These two otherworldly creatures are predator and prey. On the left: the blue sea slug. On the right: the deadly tentacle of the Indo-Pacific Portuguese man o’ war.

Both were washed ashore as part of a mass stranding of man o’ wars in South Africa. The Indo-Pacific Portuguese man o’ war is a ruthless killer, using its single, long tentacle to stun and capture its prey. But the sea slug is more than a match. Not only does this tiny (3cm-long) nudibranch feed on man o’ wars, but it also steals their poison. The sea slug is immune to the man o’ wars stinging cells (nematocysts), so it consumes them and stores them in the tips of its impressive tendrils, or ‘cerata’, where they help to defend against other foes.

The sea slug is also very well camouflaged. Its blue side faces upwards, blending in with the ocean when seen by seabirds from above, while its silvery-grey side faces downwards, helping it to merge with the ocean surface when the slug is seen from below.