phylum mollusca Flashcards
What is the Phylum Mollusca known for?
Includes snails, slugs, octopus, clams
It is the second most diverse phylum.
Are all members of Phylum Mollusca soft-bodied?
Yes, but some have a protective shell
Slugs and octopus have completely lost their internal shell, while squids have a reduced one.
What are the three main parts of the Mollusca body plan?
- Muscular foot for locomotion
- Visceral mass containing most internal organs
- Mantle that covers the visceral mass and connects it to its shell
What is the mantle cavity in Mollusca?
A water-filled chamber that houses gills, anus, and excretory pores
What is a radula?
A scraping structure used for feeding
What class do chitons belong to?
Class Polyplacophora
Describe the body structure of chitons.
Oval shaped body composed of 8 dorsal plates
What is the primary function of the foot in chitons?
Allows for locomotion and suction to surfaces
What percentage of all molluscs are in Class Gastropoda?
¾ of all molluscs
How do most gastropods move?
By ripping motion through contractions of the foot
What unique feature do terrestrial gastropods lack?
Gills
What is torsion in gastropods?
180 degree twisting of the body positioning the anus behind the head
What class do clams, oysters, mussels, and scallops belong to?
Class Bivalvia
How is the shell of bivalves structured?
Divided into two halves connected by a hinge
What type of feeders are bivalves?
Filter feeders
How are pearls formed in bivalves?
Formation of nacre around a contaminant until it is removed from the soft tissue
What class do squids, octopus, and nautiluses belong to?
Class Cephalopoda
What is the primary method of predation in cephalopods?
Tentacles grasp prey
What modification does the foot of cephalopods undergo?
Modified into a muscular siphon and part of tentacles
What circulatory system do cephalopods possess?
Closed circulatory system
What is unique about the nervous system of cephalopods?
Most complex nervous system in invertebrates
What are chromatophores?
Pigment cells that can change the color of the animal
True or False: Cephalopods have the most complex brain among mollusks.
True
Cephalopods have eyes similar in structure to _______.
[vertebrate eyes]
