Download - Bivalves and Gastropods
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BIVALVES AND GASTROPODSMae Gallego 9A
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Kingdom: Animalia G. Phyla: Molusca
i.)Sub-phyla: Gastropods/Bivalves
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GASTROPODA
From ancient Greek Prefix γαστήρ gastr- stomach Sufix πούς pod- foot 325,000 species currently existing
-only 85 thousand have accepted names
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GASTROPOD CHARACTERISTICS
Have shell Univalves Torted body Anus and head are together Well defined head 2-4 sensory tentacles with eyes Moves gliding along a surface Leaves mucus or slime produced
by glands on the foot. Invertabrate
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BIVALVIA Name describes the shape of the shell. Also known as:
Pelecypoda (axe foot) Acephala (no head) Lamellibranchia (plate-like gill elements)
aprox. 9,200 species
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CHARACTERISTICS Shell (2 asymmetrically rounded
halves) Made of calcium carbonate
Hinge (flexible ligament that joins the valves)
Most live in water No defined head Breathe-only one/two pairs of gills Have no brain Can live in water with a pH greater
than 5 Mostly sedentary
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GASTROPOD FOSSIL RECORD Most are fossils of the shell
Few slug fossils Earliests-exclusively marine (end of
Cambrian)
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BIVALVE FOSSIL RECORD 1st from the Cambrian
period 510 million years ago
Most abundant during the Devonian period 400 million years ago
During Paleozoic period- near shore enviroments.
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GASTROPOD LIFE CICLE
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BIVALVE LIFE CYCLE
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DIGESTIVE SYSTEM Gastropods:
Mostly hervibores or scavangers Use radula to eat
tongue-like structure-rows of rasping teeth. Adapts to the food it eats
Stomach is above foot Vivalves:
Filter feeding (gills) Scraping detritus from bottom (most primitive) Intercellular digestion
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RESPIRATORY SYSTEM Lungs or gills
Depending on the habitat Respiratory protein: Hemocyanin Bivalves
Water currents enable the organism to get fresh oxygen.
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CIRCULATORY SYSTEM Open circulatory system Gastropods:
2 chamber heart Auricle (recieves the haemolymph) Ventricle (pumps haemolymph into the aorta)
Haemolymph Circulatory fluid
Short aorta Divided in 2 main vessels
Bivalves: 3 chamber heart
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SENSORY SYSTEM Gastropods
Olfactory Mechanorceptor Statocyst Eyes or visual organ Central nervous
system Bivalves
Poor nervous system and sensory organs
Chemosensory cells at edge of mantle
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ANY QUESTIONS, COMENTS ETC?
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BIBLIOGRAPHY http://www.google.es/imgres?q=snail+circulatory+system&um
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http://en.wikipedia.org/wiki/File:CyprusPlioceneGastropod.JPG http://en.wikipedia.org/wiki/Fossil_record http://en.wikipedia.org/wiki/Gastropoda http://www.natureduca.com/zoo_inverteb_moluscos3.php http://encina.pntic.mec.es/nmeb0000/invertebrados/moluscos/
gruposmoluscos/gasteropodos.html http://www.scholarpedia.org/article/Gastropod_reproductive_be
havior http://en.wikipedia.org/wiki/Gastropoda http://www.manandmollusc.net/advanced_introduction/moll101
gastropoda.html http://micropig.tumblr.com/post/807759651/dragon-slug-how-d
o-you-exist http://www.google.es/search?q=slug&um=1&ie=UTF-8&hl=es
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http://www.manandmollusc.net/advanced_introduction/mollusca_101_intro.html
http://www.kgs.ku.edu/Extension/fossils/bivalve.html http://infusion.allconet.org/webquest/PhylumMollusca.html http://www.waterencyclopedia.com/Bi-Ca/Bivalves.html#b