11.2.5 Quiz


Test your knowledge and understanding of Class Cephalopoda by completing the quiz below.

Question

Is the cephalopod shell shown above evolute, convolute, or involute?

Answer

The shell has convolute coiling because the youngest whorls partially cover earlier whorls.

Question

What are aptychi? (See example above.)

Answer

Aptychi are paired structures that look superficially like bivalve shells. They are thought to be parts of the bodies of ammonoids, but their function(s) remain uncertain.

Question

What are the structures called that separate the internal chambers of nautiloid and ammonoid shells?

Answer

Sutures. These are relatively simple in shape in nautiloids, but much more complex in some ammonoids.

Question

Is this shell a nautiloid or an ammonoid? How do you know?

Answer

The shell is a nautiloid. Its sutures are very simple in shape. If it were an ammonoid, the sutures would be much more complex.

Question

What is the primary function ofchromatophores in modern coleoids?

Answer

Chromatophores allow coleoids to rapidly change color.

Question

What specific kind of cephalopod is shown above?

Answer

This is a baculite, a type of straight-shelled ammonite.

Question

Characterize the shape of the cephalopod shell above (it looks like a snail shell, but is not).

Answer

This specimen of heteromorph ammonite has a torticone shell.

Question

What quality most readily separates heteromorphs from other ammonites?

Answer

The shells of heteromorphs are irregularly coiled (as opposed to the typically planispiral shells of most ammonoids).

Question

Characterize the shape of the shell shown above.

Answer

The shell is a gyrocone. It is curved, but earlier whorls do not touch each other.

Question

During which geological interval did nautiloids reach their peak diversity?
a) Late Paleozoic
b) Triassic
c) Cretaceous
d) Paleogene

Answer

Nautiloids reached their peak diversity during the late Paleozoic.

Question

What is a gladius?

Answer

A gladius is an rigid internal body part found in some ancient coleoids and the modern vampire squid.

Question

What is a phragmocone?

Answer

A phragmocone comprises the chambered portions of a cephalopod shell. The remainder of the shell is occupied by the living animal and is called the body chamber.

Question

What kind of modern shell is shown in the image above?

Answer

This is the Internal shell of the extant squid Spirula spirula,

Question

What kind of fossil is shown in the image above?

Answer

Beleminte. Belemintes were internal shells (guards) of squid-like animals that lived during Jurassic and Cretaceous periods.

Question

If you find an ammonoid fossil with a suture pattern that looks like the one above, most likely when (what period(s)) did the ammonoid live?

Answer

This is an ammonitic suture, so the specimen is likely from either the Jurassic or Cretaceous period.

Question

During which geological period did this cephalopod most likely live?

Answer

This specimen has a ceratite suture, indicating that it is an ammonoid that probably lived during the Triassic period.

Question

Ammonoids and coleoids are both thought to have evolved from one particular group of nautiloids. What is that group?

Answer

Ammonoids and coleoids are thought to have evolved from bactritids.

Question

Characterize the shape of the shell shown above AND identify the tube-like structure that runs down the center of the shell.

Answer

The shell is an orthoconic longicone (=straight, long shell). The central tube-like structure is the siphuncle.

Question

Do members of any major group of modern Coleoidea typically have internal shells?

Answer

Yes. Cuttlefish have internal, chambered shells called "cuttlebones."

Question

What structure is indicated by the top arrow? What structure is indicated by the bottom arrow?

Answer

The top arrow indicates the siphuncle. The bottom arrow indicates a single septum.

Question

All living Coleiodea are active predators, with a single known exception. What is that exception?

Answer

The vampire squid. This species (Vampyroteuthis infernalis) uses a long filament to feed on detritus suspended in seawater.

Question

When did the ammonoids go extinct?

Answer

At the end of the Cretaceous period (=end of the Mesozoic era).

Question

Characterize the shape of the shell above.

Answer

Shell is an orthoconic brevicone (=straight, short shell).

Question

Characterize the shape of the cephalopod shell above.

Answer

The shell is a cyrtoconic longicone (=curved, long shell).

Question

Which one of the following IS NOT a feature shared by all cephalopods?
a) Beak
b) Arms
c) External shell
d) Funnel

Answer

c) External shell. Coleoids do not have external shells, though cuttlefish have an internal shell, as did belemnites.

Question

During which geological period did Nautiloidea and Coleoidea--the two major groups of extant Cephalopoda--likely diverge from one another?

Answer

Nautiloidea and Coleoidea are thought to have diverged from one another during the Devonian period. In other words, the shared common ancestor of the modern chambered nautilus and a squid lived during the Devonian.

Question

True or False: Cephalopods with ceratite sutures are completely extinct.

Answer

True. Some ammonoids had ceratitic sutures (especially during the Triassic period), but all ammonoids are now extinct.

Question

To which major group of cephalopods do octopuses belong?

Answer

Octopuses are coleoids. More specifically, they belong to the group of coleoids called Octopodiformes. Cuttlefish, squids, and belemnites are also coleoids.

Question

Which one of the following is an example a member of the Decapodiformes?
a) Nautilus.
b) Ammonite.
c) Squid.
d) Octopus.

Answer

c) Decapodiformes. The name means ten feet; squids and cuttlefish both have ten arms and are part of this clade.

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