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>> 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.
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