MOLLUSCA

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Questions and Answers

What is the distinctive feature of the pupil of belemnites?

No distinct shape

W-shape in bright light and circular in darkness (correct)

W-shape in darkness

Circular shape in bright light

Which of the following is a characteristic of the beak of belemnites?

Short and stout

Long and pointed

Absent

Parrot-like shape (correct)

How do belemnites alter their color and pattern?

By releasing ink

Through chromatophores (correct)

By moving their lateral fins

By changing the shape of their beak

What is the function of the long tentacles of cuttlefish?

To catch prey Signup and view all the answers

What is the shape of the gladius in teuthids?

Rod-like Signup and view all the answers

What is the function of the ink gland in teuthids?

To evade predators Signup and view all the answers

What is the characteristic of the posterior mantle of Sepiolidae?

Broad and rounded Signup and view all the answers

Which of the following is a characteristic of bottletail squids?

Striking color patterns Signup and view all the answers

What is the shape of the body in subclass Pulmonata?

Projectile- or sac-shaped Signup and view all the answers

How do cuttlefish capture their prey?

By aiming and rapidly shooting their tentacles to capture prey Signup and view all the answers

What is the function of the cuttlebone in cuttlefish?

To control buoyancy Signup and view all the answers

What is unique about the left fourth arm of cuttlefish?

It serves as the hetocotylus Signup and view all the answers

What type of eyes do cuttlefish possess?

Highly developed eyes Signup and view all the answers

What is the composition of the cuttlebone?

Calcareous or aragonitic Signup and view all the answers

What is the function of gills in certain mollusks?

To filter feed and aid in respiration Signup and view all the answers

What is the function of chromatophores in cephalopods?

To change color for camouflage and communication Signup and view all the answers

What is the function of the radula in cephalopods?

To reduce large food particles Signup and view all the answers

What is the characteristic of the heart in cephalopods?

It has 3 chambers with 2 auricles and 1 ventricle Signup and view all the answers

What is the function of the ink gland in cephalopods?

To evade predators Signup and view all the answers

What is the characteristic of the eyes in cephalopods?

They are big and mobile Signup and view all the answers

What is the function of cilia in certain mollusks?

To move trapped food to the mouth Signup and view all the answers

What is unique about the development of certain cephalopods?

They do not have a larval stage Signup and view all the answers

Study Notes

Belemnites

Have a distinct W-shaped pupil in bright light that changes to circular in darkness
Possess a parrot-like beak and long lateral fins for maneuvering at high speeds
Can alter their color and pattern at any time for camouflage and communication
Have a large brain to body size ratio

Sepiadariidae (Bottletail Squids)

Short, 2-4 cm in length
Benthic, found in bottom sediments of a sea or any body of water
Have striking color patterns

Cuttlefish

Can change their colors due to chromatophores
Camouflage for communication and protection
Use their very long tentacles to catch prey, moving very fast

Order Teuthida

Have a rod-like, chitinous gladius (plastic shell)
Possess chromatophores for color change
Some are bioluminescent
Have an ink gland to evade predators

Family Sepiolidae

Small, 1-10 cm in length, with a broad and rounded posterior mantle
Have ear-like fins and are benthic or pelagic
Uroteuthis sp. produces a spermatophore, common in complex chambered heart

Mollusks (Part 2)

Have a complex chambered heart with 3 chambers (2 auricles and 1 ventricle)
Absence of cilia in gills, used primarily for gaseous exchange
Gills are used for filter feeding in other mollusks (bivalves and gastropods)
Have a chitinous beak/radula used to reduce large food
Chromatophores are pigment cells for camouflage, identification, and communication
Ink gland is used to evade enemies, not only in squid but also in octopus and cuttlefish

Cephalopods

Have big and mobile eyes
Can retract their tentacles to specialized pouches in the head region
Use their tentacles to capture prey, aiming and rapidly shooting them

Subclass Pulmonata

Body is projectile- or sac-shaped
Shells are orthoconic, cyrtoconic, or rarely coiled
Possess highly developed eyes
Left fourth arm serves as hetocotylus
Have denticulated suckers surrounding the mouth

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