Phylum mollusca Flashcards
- Soft body
- Occupy a great range of habitat
- a large phylum of invertebrate animals (animals without a backbone)
Phylum mollusca
The two mollusk body plan
- Head-foot portion
- Visceral Mass
- depends primarily on muscular action for its action
- more active area, containing: Feeding, Locomotor organs, cephalic sensory
Head-foot portion
- portion containing digestive circulatory, respiratory, and reproductive organs
- depends primarily on ciliary tracts for its functioning
Visceral Mass
- Have valves or plates for protection
- Have gills lining the sides of their body
- Dorsoventrally flat with foot used as a “suction cup”
- Lives on rocky areas on the beach
- Undergoes metamorphosis
- Free-swimming larval stage * More sessile adult stage
Class polyplacophora
example of class polyplacophora
Chilton
- Have tusk-like shells
- Foot specialized for digging in the substrate
(either sand or mud) - Found in the subtidal zone (underwater)
- Have two openings: bigger opening is where the foot and tentacles emerge; smaller one used to relieve pressure
Tentacles used as feelers and for grabbing food; food particles will be shred by the radula found inside the shell - Undergoes metamorphosis
- Free-swimming larval stage * More sessile adult stage
Class scaphopoda
- Pronounced muscular foot
- Siphon used for respiration (sucking in water) or for buoyancy maintenance (sucking air or releasing air to stay afloat or to sink)
- Have radula (rows of teeth)
- Has an operculum that closes the
aperture/opening of the shell - For protection against environmental conditions (e.g. lack of water)
- For protection against predators
Class gastropod
- Have two shells connected on a hinge
- Have foot specialized for digging or pushing the substrate
- Siphons used to suck water and food particles in
- Have nacre: a shiny substance used to coat irritants and infected internal parts; creates pearl
- Eyes are usually rudimentary; only detects light and dark
- Undergoes metamorphosis
- Some have free-swimming larval stage; others have larvae that latch onto fish gills to facilitate their spread
- More sessile adult stage
Class bivalvia
- Most living members do not have external shells (except for nautilus)
- Shells are reduced as an internal, plastic-like structure
- Have well-developed eyes
- Have well-developed nervous systems
- Have beaks that are used to crush the shells of their prey
- Have pronounced and specialized tentacles
- Do not undergo metamorphosis; instead, they undergo direct development (baby to adult; no larval and adult stage)
Class cephalophoda
What are the classes that have eyes that are rudimentary
- Class Gastropoda
- Class Bivalvia
What are classes that undergoes metamorphosis?
All of them except class cephalophoda
What is a radula
Rows of teeth
Closes the aperture / opening of the shell
- protection against environmental conditions
- protection against predators
Operculum
why does class cephalophoda dont undergo metamorphosis?
because they undergo direct development instead
Clam is an example of?
Class bivalvia
Nauticus, Squid
Class Cephalophoda
Whelk
Class Gastropoda
Chilton
Class Polyplacophora
a shiny substance used to coat irritants and infected internal parts; creates pearl
Nacre
