FruitlessFetusSign upFrom this week we measure your fetus crown to heel instead of crown to rump, so the number jumps. At about 27 cm, your fetus is now the size of a single eye of the colossal squid, the largest eye of any animal that has ever lived.
A colossal squid eye can be the size of a soccer ball, around 27 cm across, with a built-in glowing organ that acts like a headlight. In the near-total darkness of the deep Southern Ocean, an eye that big can detect the faint glow of a sperm whale approaching from far away.
The squid itself may reach 10 meters and weigh half a tonne, armed with rotating hooks on its arms. Almost everything we know about it comes from carcasses found in whale stomachs, because a live adult has rarely been seen.
Meanwhile, inside you
Your baby's eyes are fully formed this week, though the lids stay fused shut while the retinas mature. Behind them, the brain is wiring up the pathways that will one day turn light into sight.