How is a nautilus different from a squid?

[MUSIC] >> NEIL LANDMAN: So I love nautilus. They’re a unique group of animals. They’ve been around on our planet for the last 5- to 600 million years and have left a remarkable record. We don’t have very much to compare it to because its so different from all other modern cephalopods. Nautilus is the most primitive of all the cephalopods. The oldest squid that we have are 350 million years but the lineage of nautilids is probably about 500 million years old. So what makes nautilus unique among all cephalopods today is this external shell. Back at the dawn of cephalopod evolution, probably all of them had shells. On the outside it seems like it’s a solid shell, but on the inside, you immediately detect that it’s a series of chambers ever-increasing in size, until you come to the body chamber, where the animal is lodged. So each of these chambers is filled with air during life, and that permits the animal to maintain a neutral buoyancy as it grows. If you look at the early embryology, you’ll see the same number of arm buds as the other cephalopods, but they develop very differently so that they develop into all of these tiny, little tentacle-like structures, called cirri, about a hundred little cirri. If you look at squids, you think of them as lunging predators. Nautilus doesn’t swim all that well. I mean, it swims perfectly well for what it needs to do, but it’s not going to be doing these predatory lunging activities. It’s going to scavenge along the bottom, looking for dead animals. So it’s a different mode of life. If you look at the common squid loligo, it produces thousands of eggs, but each egg is very small. It’s probably going to be a millimeter in size. And the newly-hatched animals are going to spend time as paralarvae. Nautilus is a very different strategy. A nautilus will lay only about a dozen eggs, the largest in the invertebrate kingdom. And embryonic development takes an extraordinarily long time, a year. A nautilus a little more than an inch in size hatches, and it begins to assume all of the behavior of an adult scavenging along the bottom. Nautilus is clearly one of the most exceptional of the cephalopods in that it grows very slowly. Most squid, octopus, cuttlefish grow very rapidly and reach maturity in a few years and die. But nautilus reaches maturity in about 20 years. So nautilus today are broadly distributed in the Indo-Pacific, and we don’t really know exactly all the places they live but at some sites, we know for sure that they have been overharvested, not for the food value, but for the ornamental value. The fact that they have very few eggs, and they’re slow-growing animals, really, really, is not good news for a population. So if you are fishing them, you risk exterminating them. Current research is revealing new sites, so there may be hope that it’s a more robust population than we think but conservationists around the world have begun to worry about the fate of nautilus. [END MUSIC]

Channel: American Museum of Natural History

Views: 163,555

Keywords: Nautilus, Cephalopod, Cephalopod week, what is a nautilus, are nautilus and squid related, how is a nautilus different from a squid, squid, octopus, cuttlefish, mollusk, explainer, nautiluses, baby nautilus, live nautilus, nautilus the animal, deep sea, ocean, ocean creature, ocean life, American Museum of Natural History, Natural History Museum, AMNH, squid footage, nautilus footage, Neil Landman, ammonite, tentacle

Id: NLfk6U0eiFE

Length: 4min 7sec (247 seconds)

Published: Sat Jun 16 2018