Cephalopods - Lecture 6

Question 1

What makes cephalopods important for fossil record?

Answer 1

Ammonites important for dating and correlating rocks

Question 2

Describe sexual dimorphism with an example

Answer 2

Sexual dimorphism is when male and females appear different. In cephalopods the female is usually larger.

Question 3

What mode of life did cephalopods pursue?

Answer 3

Predators

Question 4

What is the only living cephalopod to have a shell?

Answer 4

Nautiloids

Question 5

State when ammonites appeared and list 4 features of an ammonite

Answer 5

Ammonites existed between the Jurassic and the Cretaceous. The males are smaller than females (sexual dimorphism), they have a complex suture and they were beginning to uncoil

Question 6

Give 4 differences between ammonites and nautilus

Answer 6

Ammonites lived in shallow waters, has a small protoconch with many small eggs, ornamented shell and complex suture. Nautilis live in deep water, have a large protoconch and lay few large eggs, they have a smooth shell and have a simple suture pattern

Question 7

What is a siphuncle and what is it used for?

Answer 7

Siphuncle = organ in Nautilus that controls buoyancy Chambers filled with gas atmospheric gas) or liquid (sea water).
Nautilus can vary proportions of gas and liquid in chambers by OSMOSIS.Can extract Na and Cl ions from liquid which in chambers – change salinity. Sets up gradient between blood of animal and liquid in chambers. Therefore can remove water from chambers. Siphuncle removes water and replaces with gas Siphuncle removes gas and replaces with water - vary buoyancy & internal pressure