The Phronima's habit of hollowing out salps to raise babies

Meet the Phronima, the deep sea's most ruthless interior decorator. Instead of building a nursery, this tiny crustacean finds a salp—a peaceful, translucent jelly tube—and eats the poor thing from the inside out until only a hollowed-out husk remains.

Once the salp is just a gelatinous barrel, the Phronima crawls inside to lay its eggs. It then paddles this stolen "house" through the ocean like a morbid little submarine.

It’s a mobile home made of a victim’s skin. This nightmare fuel actually inspired the design for the queen in the movie Alien.

Wait, how does it actually steer that stolen jelly barrel?

Imagine driving a car by sticking your feet through the floorboards like a deep-sea Flintstone. The Phronima hooks its front claws into the inner walls of the salp to hold on tight, then uses its specialized swimming legs to paddle furiously through the open ends of the tube.

Because the salp is basically a ghost made of jelly, it’s super light underwater. It’s less like dragging a house and more like wearing a very thick, transparent puffer jacket that doubles as a stroller. It’s efficient, creepy, and surprisingly fast.

Won't the babies just get flushed out the back while it's paddling?

You’d think they’d be flying out like loose change in a washing machine, but the Phronima is a surprisingly attentive parent. Before the eggs even hatch, she uses a specialized biological glue to anchor them firmly to the inside walls of the salp barrel.

Once the larvae hatch, they don't just drift around; they have tiny hooks to hang onto the 'wallpaper' for dear life. It’s basically a high-speed, open-air nursery where the kids have to grip the furniture to avoid being evicted by the current.

The mother also carefully manages the water flow. She isn't just mindlessly kicking; she’s creating a specific internal circulation that keeps her brood safe while she zooms through the dark.

But how do the babies eat if they're stuck to the walls?

Nature is a brutal landlord. Since the mother already ate the salp’s internal organs to make the house, the babies can’t just snack on the walls. Instead, the mother acts like a deep-sea delivery driver.

She uses those specialized legs to create a current that sucks plankton and organic debris directly into the barrel. The babies just hang onto their hooks and grab whatever snacks float past their faces.

It’s essentially a 24/7 drive-thru where the food comes to you, provided you don't mind living inside a hollowed-out corpse.

What happens when the kids actually outgrow their stolen jelly studio?

It’s not exactly a long-term lease. As the babies grow, that jelly studio starts feeling more like a crowded elevator. Eventually, the mother’s delivery service can’t keep up with their growing appetites.

Once they’re strong enough to swim, they pull a "peace out" and unhook themselves from the walls. They drift off into the dark to find their own peaceful salps to murder.

They leave the tattered, empty husk behind like a trashed hotel room. It’s the circle of life, if the circle was made of stolen translucent skin and tiny, hungry monsters.