Difference between revisions of "AY Honors/Shells - Advanced/Answer Key"

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{{Taxobox
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{{honor_header|3|1949|Nature|General Conference}}
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| name = Molluscs
 
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| fossil_range = [[Ediacaran]] or [[Cambrian]] - Recent
 
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| image = Caribbean reef squid.jpg
 
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| image_width = 200px
 
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| image_caption = [[Caribbean Reef Squid]], ''Sepioteuthis sepioidea''
 
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| regnum = [[Animal]]ia
 
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| superphylum = [[Lophotrochozoa]]
 
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| phylum = '''Mollusca'''
 
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| phylum_authority = [[Carolus Linnaeus|Linnaeus]], 1758
 
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| subdivision_ranks = [[Class (biology)|Class]]es
 
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| subdivision =
 
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[[Aplacophora]]<br/>
 
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[[Bivalvia]]<br/>
 
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[[Caudofoveata]]<br/>
 
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[[Cephalopoda]]<br/>
 
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[[Gastropoda]]<br/>
 
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† [[Helcionelloida]]<br/>
 
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[[Monoplacophora]]<br/>
 
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[[Polyplacophora]]<br/> 
 
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† [[Rostroconchia]]<br/>
 
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[[Scaphopoda]]<br/>
 
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† [[Tentaculita]]
 
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| diversity = c.200,000 species<ref>Ponder, Winston F. and Lindberg, David R. (Eds.) (2008)  [http://www.ucpress.edu/books/pages/10802.php ''Phylogeny and Evolution of the Mollusca'']. Berkeley: University of California Press. 481 pp. ISBN 978-0520250925.</ref>
 
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| diversity_link = Mollusca
 
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}}
 
  
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'''Molluscs''' ([[British English|British]] spelling) or '''mollusks''' ([[American English|American]] spelling) are animals belonging to [[Phylum (biology)|phylum]] '''Mollusca'''. The word ''[[wikt:mollusc|mollusc]]'' is derived from the [[French language|French]] ''mollusque'', which originated from the [[Latin]] ''molluscus'', meaning thin-shelled, from ''[[wikt:mollis|mollis]]'', soft<ref>Mollusc. (n.d.). ''The American Heritage Dictionary of the English Language, Fourth Edition''. Retrieved [[March 19]], [[2008]], from Dictionary.com website: http://dictionary.reference.com/browse/mollusc</ref>. The [[science|scientific]] study of molluscs is known as '''[[malacology]]'''.
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==1. Have the Shell Honor. ==
 +
{{Ay prerequisite|Nature|Shells}}
 +
==2. Define the term "mollusca" or "mollusk." ==
 +
The word ''mollusc'' is derived from the French ''mollusque'', which originated from the Latin ''molluscus'', meaning thin-shelled, from ''mollis'', soft
  
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There are around 100,000 [[extant taxon|extant]] [[species]] within the phylum<ref name=barnes01>Barnes, R.S.K., Calow, P., Olive, P.J.W., Golding, D.W. and Spicer, J.I. (2001).  ''The Invertebrates, A Synthesis'' (3rd Edition), Blackwell Science, UK.</ref> with an estimated 70,000 [[extinct]] species<ref name=brusca03>Brusca, R.C. & Brusca, G.J. (2003).  ''Invertebrates'' (2nd Edition), Sinauer Associates Inc., MA, USA.</ref>.  They range widely in size from [[micromollusk]]an snails and clams to larger organisms such as the [[Colossal Squid]], believed to be the world's largest [[invertebrate]].  Molluscs are typically divided into ten [[Taxonomy|taxonomic]] [[class (biology)|classes]], of which two are entirely [[extinct]]<ref name=barnes01/><ref name=brusca03/>.  Class [[Cephalopod]]a molluscs such as [[squid]], [[cuttlefish]] and [[octopus]] are among the most [[neurobiology|neurologically-advanced]] of all invertebrates<ref name=barnes01/>.
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The body of a mollusk consists of three sections; a head, with eyes or tentacles; a muscular foot; and a visceral mass housing the organs.
  
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The majority of mollusc species live in [[marine]] environments, and many of them are found [[intertidal zone|intertidally]], in the shallow subtidal and on the [[continental shelf]]. [[Pelagic zone|Pelagic]] species of octopus and squid live throughout the [[water column]] of the ocean, and some species of clam and limpet live in the abyssal depths of the oceans around hot [[hydrothermal vent]]s.  However, not all molluscs are marine: the [[bivalve]] and [[gastropod]] classes also contain freshwater species, and the gastropods additionally have representatives that live on land, the land [[snail]]s and [[slug]]s.
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==3. Learn the classification terms of mollusks, know the distinguishing characteristics of each, and become acquainted with several species under each class. ==
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There are ten classes of molluscs; eight of the classes have living representatives, the other two classes are known only from fossils. More than 250,000 species of mollusc are recognized and named. Snails (Gastropoda) account for about 80% of living mollusc diversity.
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A number of species of molluscs are valued by humans as [[seafood]], or for their decorative [[seashell|shells]].  Edible species include various clams, snails, squid and octopuses.
 
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==Anatomy==
 
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{{see|Mollusc shell}}
 
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[[Image:Calliostoma tigris.JPG|thumb|left|220px|The shell of the tiger top snail, ''[[Calliostoma tigris]]'', from New Zealand.]]
 
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Molluscs are [[triploblastic]] [[protostome]]s and many demonstrate [[Symmetry (biology)#Bilateral symmetry|bilateral symmetry]]. The principal [[body cavity]] is a blood-filled [[hemocoel]]. They have a true [[body cavity|coelom]] (eucoelom); any coelomic cavities have been reduced to vestiges around the [[heart]]s, [[gonad]]s, and [[metanephridium|metanephridia]] ([[kidney]]-like organs). The body is often divided into a head, with [[eyes]] or [[tentacles]], a muscular foot, and a [[Viscus|visceral]] mass housing the organs.
 
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Molluscs have a [[Mantle (mollusc)|mantle]], which is a fold of the outer skin lining the shell, and a muscular foot that in most species is used for locomotion. In most molluscs the mantle secretes a [[calcium carbonate]] external shell. In the majority of marine molluscs the [[gill]] or gills absorbs [[oxygen]] from the water.  
 
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All species of the phylum Molluscs have a complete [[digestive tract]] that starts from the [[mouth]] and runs to the [[anus]]. Many have a feeding structure, the [[radula]], mostly composed of [[chitin]]. This radula is a feature only found in molluscs. Radulae are very diverse within the Mollusca, ranging from structures used to scrape [[algae]] off rocks, to the harpoon-like structures of [[cone snail]]s. [[Cephalopods]] ([[squid]], [[octopus]]es, [[cuttlefish]]) also possess a chitinous beak. Unlike the closely related [[annelid]]s, molluscs lack body segmentation. 
 
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[[Image:Tonicella-lineata.jpg|thumb|220px|The [[chiton]] ''[[Tonicella lineata]]'']]
 
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Development passes through one or two [[trochophore]] stages, one of which, (the [[veliger]]), is unique to the group. These larval stages suggest a close relationship between the molluscs and various other protostomes, notably the [[Annelid]]s.
 
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The [[giant squid]], which until recently had not been observed alive in its adult form,<ref>Kubodera, T. & Mori, K. (2005) {{PDFlink|1=[http://www.journals.royalsoc.ac.uk/openurl.asp?genre=article&issn=0962-8452&volume=272&issue=1581&spage=2583 First-ever observations of a live giant squid in the wild.]}} ''Proceedings of the Royal Society B: Biological Sciences'' '''272''' (1581), 2583-2586.</ref> is one of the largest invertebrates; however the [[colossal squid]] is even larger.{{Fact|date=July 2008}}
 
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==Classification==
 
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There are ten [[class (biology)|classes]] of molluscs; eight of the classes have living representatives, the other two classes are known only from fossils. More than 250,000 species of mollusc are recognized and named. Snails (Gastropoda) account for about 80% of living mollusc diversity.<ref>Ponder, Winston F. and Lindberg, David R. (Eds.) (2008) [http://www.ucpress.edu/books/pages/10802.php ''Phylogeny and Evolution of the Mollusca'']. Berkeley: University of California Press. 481 pp. ISBN 978-0520250925.</ref>
 
  
 
<center>
 
<center>
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{|  
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{| border=1 cellpadding=5
 
|width="110" | '''Class'''
 
|width="110" | '''Class'''
 
|width="300" | '''Major organisms'''
 
|width="300" | '''Major organisms'''
Line 57: Line 18:
 
|width="120" | '''Distribution'''
 
|width="120" | '''Distribution'''
 
|-
 
|-
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| [[Caudofoveata]]     || worm-like organisms || 70 || deep ocean
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| Caudofoveata    || worm-like organisms || 70 || deep ocean
 
|-
 
|-
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| [[Aplacophora]]     || [[Neomeniomorpha|solenogasters]], worm-like organisms || 250 || deep ocean
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| Aplacophora      || solenogasters, worm-like organisms || 250 || deep ocean
 
|-
 
|-
−
| [[Polyplacophora]]   || chitons || 600 || rocky marine shorelines
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| Polyplacophora  || chitons || 600 || rocky marine shorelines
 
|-
 
|-
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| [[Monoplacophora]]   || limpet-like organisms || 11 || deep ocean
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| Monoplacophora  || limpet-like organisms || 11 || deep ocean
 
|-
 
|-
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| [[Gastropoda]]       || [[abalone]], [[limpet]]s, [[conch]], [[nudibranch]]s, [[sea hare]]s, [[sea butterfly]], [[snail]]s, [[slug]]s || 150,000<ref>Ponder, Winston F. and Lindberg, David R. (Eds.) (2008) [http://www.ucpress.edu/books/pages/10802.php ''Phylogeny and Evolution of the Mollusca'']. Berkeley: University of California Press. 481 pp. ISBN 978-0520250925.</ref> || marine, freshwater, land
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| Gastropoda      || abalone, limpets, conch, nudibranchs, sea hares, sea butterfly, snails, slugs || 150,000<ref>Ponder, Winston F. and Lindberg, David R. (Eds.) (2008) [http://www.ucpress.edu/books/pages/10802.php ''Phylogeny and Evolution of the Mollusca'']. Berkeley: University of California Press. 481 pp. ISBN 978-0520250925.</ref> || marine, freshwater, land
 
|-
 
|-
−
| [[Cephalopod]]a     || [[squid]], [[octopus]], [[cuttlefish]], [[nautilus]] || 786 || marine
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| Cephalopoda     || squid, octopus, cuttlefish, nautilus || 786 || marine
 
|-
 
|-
−
| [[Bivalvia]]         || [[clam]]s, [[oyster]]s, [[scallop]]s, [[mussel]]s || 8000 || marine, freshwater
+
| Bivalvia        || clams, oysters, scallops, mussels || 8000 || marine, freshwater
 
|-
 
|-
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| [[Scaphopoda]]       || tusk shells || 350 || marine
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| Scaphopoda      || tusk shells || 350 || marine
 
|-
 
|-
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| [[Rostroconchia]] †  || fossils; probable ancestors of bivalves || [[extinct]] || —
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| Rostroconchia †  || fossils; probable ancestors of bivalves || extinct || —
 
|-
 
|-
−
| [[Helcionelloida]] † || fossils; snail-like organisms such as ''[[Latouchella]]'' || extinct || —
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| Helcionelloida † || fossils; snail-like organisms such as ''Latouchella'' || extinct || —
 
|-
 
|-
 
|}
 
|}
 
</center>
 
</center>
  
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==Evolution==
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==4 Distinguish between univalve and bivalve mollusks from the following considerations: ==
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{{main|Evolution of Mollusca}}
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===a. Shell  ===
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{| border="0" cellpadding="2" cellspacing="0" align="right"
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===b. Mollusk body  ===  
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|-
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===c. Reproduction===
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|bgcolor="#BBBBBB"|&nbsp;
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===d. Movements===
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|bgcolor="#AAAAAA"|&nbsp;
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===e. Securing food===
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|bgcolor="#AAAAAA"|&nbsp;
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===f. Self-preservation===
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|bgcolor="#AAAAAA"|&nbsp;
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==5. Identify from shells or drawings and know the meaning of the following concho logical terms: ==
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|bgcolor="#AAAAAA"|&nbsp;&nbsp;
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===a. Valve  ===  
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|align="right" bgcolor="#AAAAAA"|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Caudofoveata (?)
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===b. Apex  ===
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|-
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===c. Aperture ===
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|bgcolor="#BBBBBB"|&nbsp;
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===d. Byssus  ===
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|bgcolor="#EEEEEE"|&nbsp;
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===e. Foot ===
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|bgcolor="#EEEEEE"|&nbsp;
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===f. Mantel ===
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|bgcolor="#EEEEEE"|&nbsp;
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===g. Operculum===
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|bgcolor="#EEEEEE"|&nbsp;&nbsp;
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===h. Mother of pearl===
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|align="right" bgcolor="#EEEEEE"|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Aplacophora
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===i. Epidermis===
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|-
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===j. Ribs===
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|bgcolor="#BBBBBB"|hypothetical
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===k. Teeth===
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|bgcolor="#CCCCCC"|&nbsp; &nbsp; &nbsp;&nbsp;
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===l. Concentric lines===
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|bgcolor="#AAAAAA"|&nbsp;
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===m. Canal===
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|bgcolor="#AAAAAA"|&nbsp;
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===n. Spines===
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|bgcolor="#AAAAAA"|&nbsp;&nbsp;
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===o. Whorls===
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|align="right" bgcolor="#AAAAAA"|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Polyplacophora
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===p. Lips===
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|-
 
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|bgcolor="#BBBBBB"|ancestral
 
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|bgcolor="#CCCCCC"|&nbsp;
 
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|bgcolor="#DDDDDD"|&nbsp;
 
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|bgcolor="#DDDDDD"|&nbsp;
 
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|bgcolor="#EEEEEE"|&nbsp;&nbsp;
 
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|align="right" bgcolor="#EEEEEE"|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Monoplacophora
 
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|-
 
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|bgcolor="#BBBBBB"|mollusc
 
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|bgcolor="#CCCCCC"|&nbsp;
 
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|bgcolor="#DDDDDD"|&nbsp;
 
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|bgcolor="#DDDDDD"|&nbsp;
 
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|bgcolor="#CCCCCC"|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
 
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|align="right" bgcolor="#AAAAAA"|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Gastropoda
 
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|-
 
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|bgcolor="#BBBBBB"|&nbsp;
 
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|bgcolor="#CCCCCC"|&nbsp;
 
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|bgcolor="#DDDDDD"|&nbsp;
 
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|bgcolor="#DDDDDD"|&nbsp;
 
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|bgcolor="#CCCCCC"|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
 
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|align="right" bgcolor="#EEEEEE"|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Cephalopoda
 
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|-
 
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|bgcolor="#BBBBBB"|&nbsp;
 
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|bgcolor="#CCCCCC"|&nbsp;
 
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|bgcolor="#DDDDDD"|&nbsp;
 
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|bgcolor="#DDDDDD"|&nbsp;
 
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|bgcolor="#E8E8E8"|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
 
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|align="right" bgcolor="#AAAAAA"|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Bivalvia
 
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|-
 
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|bgcolor="#BBBBBB"|&nbsp;
 
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|bgcolor="#CCCCCC"|&nbsp;
 
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|bgcolor="#DDDDDD"|&nbsp;
 
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|bgcolor="#DDDDDD"|&nbsp;
 
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|bgcolor="#E8E8E8"|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
 
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|align="right" bgcolor="#EEEEEE"|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Scaphopoda
 
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|}
 
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It is believed that the bivalves and scaphopods are sister groups, as are the gastropods and cephalopods, as indicated in the relationship diagram to the right<ref>{{cite book|author = Brusca & Brusca|year = 1990|title = Invertebrates|location= Sunderland, Mass. | publisher=Sinauer Associates}}</ref>.
 
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In this phylum's level of organization, organ systems from all three primary [[germ layer]]s can be found:
 
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# Nervous system (with [[brain]])
 
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# Excretory system ([[nephridium]] or nephridia)
 
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#  Circulatory system (open [[circulatory system]] - except cephalopods which have a closed system)
 
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#  Respiratory system ([[gill]]s or [[lung]]s)
 
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All major molluscan groups possess a skeleton, though it has been lost through evolution in some members of the phylum. It is probable that the [[pre-Cambrian]] ancestor of the molluscs had calcium carbonate spicules embedded in its mantle and outer tissues, as is the case in some modern members.  
 
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[[Image:Chromodoris quadricolor.jpg|thumb|left|200px|The nudibranch ''[[Chromodoris quadricolor]]''.  Nudibranchs are shell-less molluscs]]
 
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The skeleton, if present, is primarily external and composed of calcium carbonate (aragonite or calcite). The snail shell or [[gastropod shell]] is perhaps the best known molluscan shell, but many pulmonate and opisthobranch snails have secondarily reduced and internalized shells, or have lost the shell completely. The bivalve or clam shell consists of two pieces (valves), articulated by muscles and an elastic hinge. The cephalopod shell was ancestrally external and chambered, as exemplified by the ammonoids and nautiloids, and still possessed by ''Nautilus'' today. Other cephalopods, such as cuttlefish, have internalized the shell, the squid have mostly organic chitinous internal shells, and the octopods have lost the shell altogether.
 
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The first definitive evidence for molluscs comes from an early Cambrian radula,<ref name=Butterfield2008>{{cite journal | author = Butterfield | year = 2008 | doi = 10.1666/07-066.1 | title = An Early Cambrian Radula | journal = Journal of Paleontology | volume = 82 | pages = 543 }}</ref> but the Ediacaran organism ''[[Kimberella]]'' is held by some to be an ancestral mollusc.
 
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==Dangerous molluscs==
 
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[[Image:Hapalochlaena lunulata.JPG|thumb|220px|The [[blue-ringed octopus]], ''Hapalochlaena lunulata'', has a dangerous bite.]]
 
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A very small minority of molluscs can represent a serious risk to humans under the wrong circumstances.  
 
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All octopuses are venomous<ref name=and95>Anderson, R.C. (1995) Aquarium husbandry of the giant Pacific octopus. ''Drum and Croaker'' '''26''':14-23</ref> but only a few species pose a significant threat to humans, such as octopuses in the genus ''[[Blue-ringed octopus|Hapalochlaena]]'' which have a very poisonous bite.  A few of the larger tropical [[cone snail]] species have a very poisonous sting. These bites and stings can sometimes be fatal.  
 
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Some people are severely allergic to shellfish as a food item. However, even for people without these allergies, clams can sometimes be risky to eat. When there is a "[[red tide]]", or other blooms of noxious [[plankton]], or when there are high concentrations of bacteria in the water from sewage run-off, bivalves such as clams and mussels can temporarily become very problematic as a food source. This is because bivalves are filter-feeders, and thus they can concentrate toxins from floating microorganisms within their tissues.
 
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The traditional idea that the [[giant clam]] can trap the leg of a person between its valves, thus drowning them, has been shown to be a myth.
 
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Despite its name, the disease [[molluscum contagiosum]] is caused by a [[virus]], and is not connected with molluscs in any way.
 
  
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[[Image:2005mollusc.PNG|thumb|left|Mollusc output in 2005]]
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==6. Explain the development of a shell. How long do mollusks live?==  
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==Aquaculture==
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==7. Give some facts about the life of a strombus pugilis (fighting conch) and explain why this shell is so named. ==
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In 2005, China accounted for 80 per cent of the global mollusc catch according to a [[FAO]] study.<ref>[http://www.fao.org/figis/servlet/TabLandArea?tb_ds=Capture&tb_mode=TABLE&tb_act=SELECT&tb_grp=COUNTRY China catches almost 11m tonnes of molluscs in 2005]</ref> Within Europe, France remained the industry leader.
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==8. Explain the activities of the shipworm. ==
 +
{{:Adventist Youth Honors Answer Book/Nature/Shipworm}}
  
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{{sisterlinks|Mollusc}}
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==9. What accounts for the distribution of mollusks.==
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{{Wikispecies|Mollusca}}
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==10. Name two mollusks that have no shells. ==
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{{Wikibookspar|Dichotomous Key|Mollusca}}
+
<gallery>
 +
Image:Unknown slug on rhubarb.jpg|<center>Slug</center>
 +
Image:Octopus in sea life Helsinki.jpg|<center>Octopus</center>
 +
Image:Cuttlefish.jpg|<center>Cuttlefish</center>
 +
Image:Mastigoteuthis flammea.jpg|<center>Squid</center>
 +
</gallery>
  
 +
==11. Find answers for the following interesting questions: ==
 +
===a. How are bivalve and univalve animals fastened to their shells? ===
 +
===b. How is shell color controlled? ===
 +
===c. What mollusk has four gills? ===
 +
===d. From what sea animal was India ink formerly made? ===
 +
===e. What mollusk spins a silken thread? ===
 +
===f. What shells were used for money by ancient tribes? ===
 +
===g. What shell is considered sacred by the Tibetans? ===
 +
===h. Purple dye of ancient times came from the secretion of what mollusk? ===
 +
===i. What is the source of pearls? How are they formed? ===
 +
==12. Name six commercial uses for shells. ==
 +
==13. Do one of the following: ==
 +
===a. Personally find and collect 40 species of shells representing the five classifications. List each shell as to the place and date it was found, common name, scientific name, and class. ===
 +
===b. Make a collection of 50 species of shells you have found, received, or purchased representing the five classifications. List each shell collected as follows: if personally found, give the information called for under letter "a" above; if received or purchased, give the name of the person from whom the shell was received, the habitat of the shell, the date of its acquisition, and its common name, scientific name, and class.===
 
==References==
 
==References==
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{{reflist}}
+
[[Category:Adventist Youth Honors Answer Book|{{SUBPAGENAME}}]]
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====General references====
 
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{{refbegin}}
 
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* {{cite book|author = Starr & Taggart|year = 2002|title = Biology: The Unity and Diversity of Life|location= Pacific Grove, California | publisher=Thomson Learning}}
 
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* Nunn, J.D., Smith, S.M., Picton, B.E. and McGrath, D. 202. ''Checklist, atlas of distribution and bibliography for the marine mollusca of Ireland.'' in. Marine Biodiversity in Ireland and Adjacent Waters. Ulster Museum. publication no. 8.
 
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* Ponder, Winston F. and Lindberg, David R. (Eds.) (2008) [http://www.ucpress.edu/books/pages/10802.php ''Phylogeny and Evolution of the Mollusca'']. Berkeley: University of California Press. 481 pp. ISBN 978-0520250925.
 
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{{refend}}
 
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==External links==
 
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* [http://www.conchology.be/en/home/home.php - 210,000 mollusca pictures.]
 
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* [http://www.gastropods.com/ Hardy's Internet Guide to Marine Gastropods]
 
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* [http://www.petsnails.co.uk/species/ Molluscs in captivity]
 
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[[Category:Molluscs|*]]
 
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[[ar:رخويات]]
 
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[[zh-min-nan:Nńg-thé tōng-bu̍t]]
 
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[[bg:Мекотели]]
 
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[[ca:Mol·lusc]]
 
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[[cs:Měkkýši]]
 
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[[cy:Molwsg]]
 
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[[da:Bløddyr]]
 
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[[de:Weichtiere]]
 
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[[et:Limused]]
 
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[[el:Μαλάκια]]
 
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[[es:Mollusca]]
 
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[[eo:Molusko]]
 
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[[fa:نرم‌تنان]]
 
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[[fr:Mollusca]]
 
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[[ko:연체동물]]
 
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[[hr:Mekušci]]
 
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[[io:Molusko]]
 
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[[id:Mollusca]]
 
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[[ia:Mollusco]]
 
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[[is:Lindýr]]
 
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[[it:Mollusca]]
 
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[[he:רכיכות]]
 
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[[la:Mollusca]]
 
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[[lv:Moluski]]
 
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[[lb:Weechdéieren]]
 
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[[lt:Moliuskai]]
 
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[[hu:Puhatestűek]]
 
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[[mk:Мекотели]]
 
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[[nl:Weekdieren]]
 
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[[ja:軟体動物]]
 
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[[no:Bløtdyr]]
 
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[[nn:Blautdyr]]
 
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[[oc:Mollusca]]
 
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[[pl:Mięczaki]]
 
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[[pt:Moluscos]]
 
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[[ro:Moluscă]]
 
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[[qu:Llamp'u uywa]]
 
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[[ru:Моллюски]]
 
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[[simple:Mollusc]]
 
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[[sk:Mäkkýše]]
 
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[[sl:Mehkužci]]
 
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[[sr:Мекушци]]
 
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[[fi:Nilviäiset]]
 
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[[sv:Blötdjur]]
 
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[[ta:மெல்லுடலி]]
 
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[[te:మొలస్కా]]
 
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[[th:หอย]]
 
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[[vi:Động vật thân mềm]]
 
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[[tr:Yumuşakçalar]]
 
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[[uk:Молюски]]
 
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[[zh:软体动物]]
 

Revision as of 03:24, 2 August 2008

Template:Honor header

1. Have the Shell Honor.

Template:Ay prerequisite

2. Define the term "mollusca" or "mollusk."

The word mollusc is derived from the French mollusque, which originated from the Latin molluscus, meaning thin-shelled, from mollis, soft

The body of a mollusk consists of three sections; a head, with eyes or tentacles; a muscular foot; and a visceral mass housing the organs.

3. Learn the classification terms of mollusks, know the distinguishing characteristics of each, and become acquainted with several species under each class.

There are ten classes of molluscs; eight of the classes have living representatives, the other two classes are known only from fossils. More than 250,000 species of mollusc are recognized and named. Snails (Gastropoda) account for about 80% of living mollusc diversity.

Class Major organisms Extant species Distribution
Caudofoveata worm-like organisms 70 deep ocean
Aplacophora solenogasters, worm-like organisms 250 deep ocean
Polyplacophora chitons 600 rocky marine shorelines
Monoplacophora limpet-like organisms 11 deep ocean
Gastropoda abalone, limpets, conch, nudibranchs, sea hares, sea butterfly, snails, slugs 150,000& marine, freshwater, land
Cephalopoda squid, octopus, cuttlefish, nautilus 786 marine
Bivalvia clams, oysters, scallops, mussels 8000 marine, freshwater
Scaphopoda tusk shells 350 marine
Rostroconchia † fossils; probable ancestors of bivalves extinct —
Helcionelloida † fossils; snail-like organisms such as Latouchella extinct —

4 Distinguish between univalve and bivalve mollusks from the following considerations:

a. Shell

b. Mollusk body

c. Reproduction

d. Movements

e. Securing food

f. Self-preservation

5. Identify from shells or drawings and know the meaning of the following concho logical terms:

a. Valve

b. Apex

c. Aperture

d. Byssus

e. Foot

f. Mantel

g. Operculum

h. Mother of pearl

i. Epidermis

j. Ribs

k. Teeth

l. Concentric lines

m. Canal

n. Spines

o. Whorls

p. Lips

6. Explain the development of a shell. How long do mollusks live?

7. Give some facts about the life of a strombus pugilis (fighting conch) and explain why this shell is so named.

8. Explain the activities of the shipworm.

Adventist Youth Honors Answer Book/Nature/Shipworm

9. What accounts for the distribution of mollusks.

10. Name two mollusks that have no shells.

  • Slug
  • Octopus
  • Cuttlefish
  • Squid

11. Find answers for the following interesting questions:

a. How are bivalve and univalve animals fastened to their shells?

b. How is shell color controlled?

c. What mollusk has four gills?

d. From what sea animal was India ink formerly made?

e. What mollusk spins a silken thread?

f. What shells were used for money by ancient tribes?

g. What shell is considered sacred by the Tibetans?

h. Purple dye of ancient times came from the secretion of what mollusk?

i. What is the source of pearls? How are they formed?

12. Name six commercial uses for shells.

13. Do one of the following:

a. Personally find and collect 40 species of shells representing the five classifications. List each shell as to the place and date it was found, common name, scientific name, and class.

b. Make a collection of 50 species of shells you have found, received, or purchased representing the five classifications. List each shell collected as follows: if personally found, give the information called for under letter "a" above; if received or purchased, give the name of the person from whom the shell was received, the habitat of the shell, the date of its acquisition, and its common name, scientific name, and class.

References

  1. ↑ Ponder, Winston F. and Lindberg, David R. (Eds.) (2008) Phylogeny and Evolution of the Mollusca. Berkeley: University of California Press. 481 pp. ISBN 978-0520250925.
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