Chapter 16: Phylum Mollusca Flashcards
1
Q
What are the four types of food acquiring capabilities of those that fall under the phylum Mollusca?
A
- herbivorous grazers
- predaceous carnivores
- filter feeders
- parasites
2
Q
Majority of those in phylum mollusca live in what kind of environment? What are the other two not as common environments ?
A
- marine
- terrestrial
- fresh water aquatic
3
Q
Are Organisms belonging to phylum Mollusca protosomes or deuterostomes
A
- protosomes ( mouth first, anus second)
4
Q
The body plan of a Mollusc is divided into what two parts?
A
- head foot region
- visceral mass
5
Q
What is included in the head-foot portion of the Mollusc?(3)
A
- feeding, cephalic sensory and locomotor organs
6
Q
What is included in the visceral portion of a Mollusc ?(4)
A
- digestive, circulatory, respiratory and reproductive organs.
7
Q
Explain what the mantle cavity is?
- what makes up the mantle?
- whats the space between the mantle and body wall?
- The space contains what? (2)
- The mantle secretes what?
A
- two folds of skin form protective mantle
- mantle cavity
- gills (ctenidia) or a lung
- shell over the visceral mass
8
Q
Head- Foot region:
- Mollusc’s have a well developed head bearing what? (2)
- Photosensory receptors range from?
- what may be present but not always?
- Posterior to the mouth is the chief locomotor organ called the?
A
- mouth and some sensory organs
- simple to complex eyes
- tentacles
- the foot
9
Q
Radula?
- Is this specific to Mollusc’s or not?
- In the mollusca phylum this is present in all organisms except what?
- Describe the organ? Physical characteristics
- Functions? In regards to prey and the digestive tract
A
- specific to molluscs
- all except bivalves
- protruding , rasping, tongue like organ
- ribbon like membrane contains rows of tiny teeth
- it rasps particles of food off surfaces
- moves particles to digestive tract
- teeth that are very worn out are replaced
- pattern and number of teeth help in classification
- some are specialized to bore through hard material or harpoon prey
10
Q
Characteristics of the Foot:
- it’s usually located how? Ventral or Dorsal?
- It functions in what two basic concepts?
- What Are the modifications it has for varying organisms ? (3)
- Secreted mucus aids in what two things?
- Snails and bivalves do what to extend the foot?
- Burrowers extend the foot into what and do what?
- Free swimming forms have a modified the foot into what?
A
- ventral
- locomotion or substrate attachment
- A) attachment disc of limpets
B) hatchet foot of clams
C) siphon jet of squids - locomotion allowing it to glide across the substrate via cilia OR in adhesion
- extend the foot hydraulically via engorgement of blood
- extend it into mud or sand, enlarge the tip as an anchor and draw forward
- into a wing or fin like swimming agents
11
Q
Mantle and Mantle Cavity Characteristics:
- The mantle is a sheath tissue located where?and secretes what when present?
- Mantle cavity : houses what that develop from what?
- The exposed surface of the mantle functions in what?
- In aquatic molluscs continuous flow of water does what? (3)
- Products of what three systems empty into the mantle cavity?
A
- on each lateral side
L> secretes the shell when present - houses the gills or lungs that develop from the mantle
- gaseous exchange
- brings in oxygen, good and flushes out wastes
- Digestive, excretory and reproductive systems
12
Q
Cephalopods use the head and mantle to create what?
A
- jet propulsion
13
Q
Describe the mollusc gill?
- filaments?
- countercurrent blood movement?
- In most molluscs there are how many and form what?
A
- has leaf like filaments - cilia propel water across the surface
- countercurrent (blood moves one way and water in the other ) blood movement in gill absorbs oxygen efficiently
- In most molluscs two ctenidia on opposite sides form an incurrent and excurrent chambers
14
Q
Describe the characteristics of the Shell:
- If present it has been secreted and lined by what?
- Periostracum is located where and is composed of what?
- Middle prismatic layer?
- Inner Nacreous layer?
- A thick periostracum for fresh water molluscs protects them against what??
A
- mantle
- outer horny layer
L> composed of conchiolin, a tanned protein - closely packed prisms of calcium carbonate
- next to the mantle, the nacre is laid down in thin layers
- acid from leaf decay in streams
15
Q
Describe the formation of a pearl?
A
- dirt gets into the outer mantle epithelium and is passed down slowly pushing through the mantle
- protects them against irritation via foreign material
