Did ammonites live underwater?

Ammonites: Did These Ancient Creatures Really Live Underwater?

Okay, picture this: you’re strolling along a beach, maybe after a storm, and you spot a cool, spiral-shaped fossil. Chances are, you’ve just stumbled upon an ammonite! These things are seriously ancient, and they always make me wonder: what were they really like when they were alive? Well, here’s the scoop: ammonites were 100% underwater creatures. They called the oceans home for a mind-boggling 340 million years, from way back in the Early Devonian period – that’s around 415 million years ago – right up until the end of the Cretaceous period, about 66 million years ago, when they sadly disappeared along with the dinosaurs.

Marine Mollusks in a Shell

So, what exactly were ammonites? They were mollusks, related to today’s nautiluses, squids, octopuses, and cuttlefish. But here’s the cool part: unlike most of their modern relatives, ammonites sported an external shell, kind of like a nautilus, but often with more elaborate spirals. This shell wasn’t just for show; it was essential for their survival.

Think of the shell as a series of interconnected rooms, or chambers. The ammonite itself only lived in the very last, largest “room,” called the body chamber. As it grew, it would move into a bigger room, sealing off the old one behind it with a wall called a septum. Now, you might think those empty chambers were just extra baggage, but they were actually super important for buoyancy.

There was this tiny tube, the siphuncle, connecting the ammonite to all those chambers. By pumping water in and out, the ammonite could control how much gas and fluid was inside, basically turning itself into a submarine! It could rise or sink in the water column whenever it wanted. And those fancy, wavy patterns you see on ammonite fossils? Those are sutures, where the chamber walls (septa) met the shell. Some scientists think the intricate patterns helped with buoyancy too, using surface tension to hold water. Pretty neat, huh?

Where Did They Hang Out?

Ammonites were global citizens, living in oceans all over the planet. While they were definitely ocean-dwellers, figuring out exactly how deep they liked to go is still something scientists are working on. The general consensus is that most preferred shallower seas, probably no deeper than 400 meters. Some studies even suggest they were bottom feeders, hanging out between 50 and 250 meters. But honestly, they probably occupied a range of depths, with different types of ammonites adapting to different lifestyles. By studying the chemistry of well-preserved fossils, comparing them to other marine organisms, we can tell that some preferred surface waters, while others liked the deeper, darker environments closer to the seafloor.

What Did They Eat?

These guys were free swimmers, and their diet probably consisted of plankton, seaweed, and other small, slow-moving sea creatures. Some may have been active hunters, while others might have scavenged for food on the ocean floor. They likely used their tentacles to grab their meals, then chomped down with beak-like jaws.

The End of the Line

Unfortunately, ammonites didn’t last forever. Like the dinosaurs, they vanished during the big extinction event 66 million years ago. This was a rough time for everyone, triggered by a massive asteroid impact that caused huge environmental changes, like a long, dark “winter” and acidic oceans. These changes hit the marine ecosystems hard, and lots of species, including the ammonites, couldn’t survive. Maybe their specialized lifestyles and the fact that their babies started as tiny plankton made them extra vulnerable.

Even though they’re gone, ammonite fossils are like little time capsules, giving us amazing insights into the history of life on Earth. From their incredible shells to the different ways they lived, these ancient sea creatures offer a fascinating glimpse into the prehistoric oceans. Every time I see one, I can’t help but imagine them swimming around in those ancient seas!