Biologists diving in the seas off Spain witnessed a European cuttlefish laying its eggs on a passing seahorse, which then swims away, eggs in tow.

The researchers believe they have filmed the European cuttlefish laying eggs in the wild for the first time.

However, during filming, one cuttlefish appears to confuse the seahorse with seaweed, laying its eggs on the passing fish despite the water being clear. (BBC©)