Question

How do nautilus and ammonites increase their flotation?

1) By secreting gas into their shells
2) By increasing their body size
3) By developing fins
4) By reducing their weight

Answer 1

Nautiluses and ammonites regulate their flotation by secreting gas into the chambers of their multi-chambered shells, using a siphuncle to control the gas and water content for buoyancy.

Step-by-step explanation:

Nautiluses and ammonites increase their flotation by secreting gas into their shells. Both possess multi-chambered shells where these chambers are filled with a mixture of nitrogen, carbon dioxide, and oxygen to control their buoyancy. A specialized structure called a siphuncle runs through these chambers, allowing the regulation of gas and water within them, fine-tuning buoyancy as needed. This adaptation allows these mollusks to navigate the ocean's depths without exerting much energy. On the other hand, increasing body size, developing fins, or reducing their weight are not the means by which nautiluses and ammonites control their buoyancy.