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32 Cards in this Set
- Front
- Back
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Mollusc |
The largest marine phylum |
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Describe the mollusc body cavity |
Coelomate |
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Describe the body symmetry of molusc |
Bilaterally symmetrical |
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What are the two types of ways mollusc fit in their shells |
1) Coiling 2) Torsion |
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Define coiling |
the body coils to acommodate within the shell one or more paired organs such as the kidney and gills may be lost
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Describe torsion |
The rearrangement of the internal organs from their traditional position by rotation of the digestive system and associated organs up to 180 degrees |
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What biome do mollusc inhabit |
1) marine, freshwater and terrestrial |
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What are the two types of shells mollusc have? |
1) internal shell( cephalapods, terrestrial slugs sand sea hares) 2) external shell |
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Success of the mollusca phylum is due to what? |
1) muscular foot for locomotion, secretes mucuous which reduces friction and creates a surface for gliding
2) Visceral mass containing internal organs
3) mantle which is a heavy fold of tissue modified epidermis that surrounds the visceral mass and secretes the shell. Mantle often has retractor muscles associated with it that allows the shell to be pulled down over the body. |
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ospharadium |
Sense organ in the mollusc which monitors that water current and the content of sediments or volatiles that may be drawn |
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Body segmentation of mollusc |
No body segmentation |
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Describe the circulatory system of mollusc |
Open circulatory system/haemocoel except for cephalapods squids and octopods which have closed systems. |
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How do mollusc feed? |
A mouth region has a raduala with many rows of chitinous teeth whcih is a specialized organ for scraping organic materials from rocks or other hard surfaces |
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Describe the sex of mollusc |
Hermaphroditic or diocious and produce a trocohpore larva. |
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What are the five classes of mollusca |
1) aplacaphorha 2)polyplachaphora 3)bivalva 4)gastrapoda 5) cephalapoda |
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Describe whats special about the aplacaphora |
No shell secreted instead a tiny calcerous spicule is secreted giving them a beautiful shine ( no internal shell either) |
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Describe whats special about the polyplachaphora |
The animals in this group, called chitons, have their dorsal surface protected by 8 overlapping plates or "valves" |
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Describe whats special about gastropods |
Snails and slugs. Snails have a single shell ("univalves') while slugs have none |
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Describe locomotion of gastropods |
locomotion by gliding on foot |
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Describe respiration of gastropod |
The mantle usually holds the gills |
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Describe the mode of feeding for gastropods |
Gastropods feed via the use of a radula. This is a very diverse mode of feeding |
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What are the four types of radula |
1) Simple 2) Rasping 3)shredding 4)Piercing 5)Drilling |
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Describe torsion in gastropoda |
a) a process in which the posterior end rotates overhead in two phases ; first phase is muscular, second is morphogenetic ( differentiation and growth of tissues and organs during development)
b) All componets of the visceropallium ( shell, mantle mantle cavity with contained structures, and viscera) rotated by 180 degrees relative to the head and foot
c)mantle cavity , openings to anus and excretory systems become anteriorn. Many body asymmetries resulted (loss of one gill/tinedia in some twisted nervous system, unequal gonads and kidneys) |
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Describe reproduction in gastropods |
Some free spawn, some copulate and some lay egg masses/ capsules. Many marine species pass through a trochophore larva stage. |
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What are the three subclasses of gastropods |
1)Prosobranchia 2)Opisthobranchia 3)Pulmonata
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Prosobranchia |
-Marine snails with large shells
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Opisthobranchia |
Sea slugs
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Pulmonata |
Land snails and slugs shell present in some absent in others |
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What is the name of the muscle that keeps the bivalve shell together |
A hinge muscles |
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Describe the mantle of the bivalve |
It is divided into two lateral lobes enclosing the whole body |
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How do bivalves eat |
Via filter feeding |
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Where do Bivalves live |
Marine or freshwater |
