Week 16: your baby is the size of a round-eared sengi

Your fetus is now the size of a round-eared sengi, a 10 to 12 cm desert animal from the Karoo and the Namib with a twitchy tubular snout, enormous dark eyes, and ears set on the sides of its head like two coins. It weighs about as much as a golf ball.

Here is the twist. Despite looking like a long-nosed mouse, it is not a rodent or a shrew at all. Sengis belong to Afrotheria, an ancient African branch that also includes elephants, aardvarks, and manatees, The flexible snout evolved on its own, but it is hard not to see a tiny cousin of the trunk.

Sengis are fastidious and fast. They keep networks of cleared trails through the scrub, sweeping them daily, and bolt along them to escape predators. This one barely drinks, taking most of its water from insects, and covers a lot of ground in a night of foraging.

Meanwhile, inside you

Your fetus this week is around the same length and is developing coordinated limb movements. Their eyes, though still fused shut, can now sense light filtering through the belly.