Each spring, thousands of firefly squid gather in Japan’s Toyama Bay and light up the water with their neon-blue bioluminescence. After laying and fertilising their eggs, they die. A year later, their offspring will return to do the same.

The Japanese pygmy squid — one of the world’s smallest cephalopods with a mantle length of just 16 mm (0.6 in) — hunts crustaceans up to twice its size. It paralyses them, then slips its mouthparts inside their exoskeletons to slurp out their insides, leaving their shells intact.

The coconut octopus carries seashells or coconut shells beneath its arms as it travels — using a few of its arms to hold the shells and the others to walk awkwardly along the sea floor. If this octopus encounters danger, it assembles the shells around itself, forming a kind of armour.