If you’ve never seen a nautilus before, you may have thought that they came from a story about alien invaders, not from our very own oceans. The chambered nautilus isn’t actually an alien but rather an ancient cephalopod (sef-uh-luh-pod). They have swum in our oceans for around 400 million years and have hardly changed in all that time. Chambered nautiluses are related to octopus, squid, and cuttleﬁsh. The nautilus is kind of the rebel of the family and has some major differences from its relatives. One big difference is that unlike the other members of its family, the nautilus can’t change color. Like other cephalopods the nautilus has a squishy body. Unlike their family members, nautiluses have hard outer shells. Imagine a squid peeking out of a snail shell. The nautilus’s hard shell helps protect the animal from getting a bite taken out of them, and it is also essential for getting around.
What does a shell have to do with swimming?
The shell of the chambered nautilus is ﬁlled with — you guessed it — chambers! When they ﬁrst hatch, the tiny nautilus has about four chambers. As the creatures grow up, more chambers develop. Adults have around 30 chambers! The nautilus’s body is in the biggest chamber, and the other chambers are used for rising and diving. The chambers are ﬁlled with gas, which helps the nautilus ﬂoat. If they want to move up or down, water can be added or removed through canals that connect all of the chambers. We’ve got up and down covered, so what about side to side? To move backwards, nautiluses have small tubes called siphons near their tentacles. The siphon shoots water with enough pressure to move the nautilus in the opposite direction.
The number of chambered nautiluses in the ocean is going down. The biggest reason is that people take the animals out of the ocean to collect their shells. Luckily, it’s easy to be a friend to the nautilus. Don’t buy anything made from a nautilus shell, and tell your friends and family to do the same. The shells make a pretty trinket, but they look much better in the ocean where they belong!