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24 Cards in this Set
- Front
- Back
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Phylum Mollusca general characteristics
6 + 1 exception |
1.Triploblastic protostomes
•True coelom •Exoskeleton •Bilateral symmetry •Unsegmented •Open circulatory system* –Hemolymph instead of blood *except cephalopods, which have a closed circulatory system |
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Phylum Mollusca common body plan (4)
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1.Shell*
-Hard outer covering 2.Foot -Locomotion or attachment to substrate 3. Visceral Mass -Contains various organs 4. Mantle secretes the shell * Reduced in some species |
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Closed circulatory system
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(Annelids and cephalopods) Blood is enclosed within vessels at all times of circulation.
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open circ system
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(Molluscs except cephalopods) Hemolymph usually replaces blood. The heart pumps the hemolymph into open sinuses where it bathes the organs/nutrient and gas exchange
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Adaptive Radiation
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Evolution of many different morphological types from a single ancestral form following migration into new environment
•New niches to explore – reduces competition for resources |
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Classes of Phylum Mollusca -5
-key feature -ex's |
1. Phylum Gastropoda - stomach foot, have one valve ex: snails, slugs, conchs, whelks
2. Class Bivalvia - two valves hinged along one edge. ex clams, oysters, mussels, scallops 3. Class Cephalopoda - head foot, ssquids, octo, nautiluses, cuttlefishes 4. Class Polyplacophora: stay at homes, suction cups: ex: chitons 5. Class Scaphopoda: curved, one piece shell, mouth with tentacles, absent head. ex: tusk shells. **Degree of cephalization varies enormously in this phylum |
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Class Gastropoda
3 items plus ex |
"stomach foot"
Examples: Snails, conch, slugs, and periwinkles •Rasping radula (tongue) •Open circulatory system •Body appears asymmetrical because of Torsion –Due to uneven growth of R and L muscles that attach the shell to head foot |
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Class Bivalvia "two valves"
ex, 3 items, feeding description of the 3rd (2 body parts) |
Examples: Clams, oysters, scallops and mussels
•Open circulatory system •Lack rasping radula •Suspension Feeders –ciliated gills trap food particles from water –Labial Palps –Transport food particles from gills to mouth |
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Class dissection anatomy - 6
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1. Adductor Muscles – used to close the valves and hold them tightly together
•Visceral Mass – contains various organs •Labial Palps – transports food from gills to mouth •Mantle – secretes shell •Foot – locomotion •Gills – respiration/filter feeding |
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Class Cephalopoda
exs plus 5 characteristics |
ex• Includes squid, cuttlefish, octopi, nautilus
• Shell reduced or absent • Mantle draws in water and contracts to force it through the siphon, which forces the same volume of water through a smaller area, creating propulsion • Well developed head with radula and eyes • Foot modified into arms or tentacles 5. * Closed circulatory system |
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Eyes of cephalopods and vertebraes is an example of
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convergent evol
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Class Polyplacophora
7 things |
•Includes chitons
•Elongated, flat body •Shell of 8 dorsal plates •Reduced head •Bilateral symmetry •Foot is broad and flat •Use radula to feed |
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Class Scaphopoda
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•Includes chitons
•Elongated, flat body •Shell of 8 dorsal plates •Reduced head •Bilateral symmetry •Foot is broad and flat •Use radula to feed |
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Phylum Annelida - 7
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•Triploblastic protostomes
•True coelom •CLOSED CIRCULATORY SYSTEM •Hydrostatic skeleton •Monoecious •Metamerism = segmentation •Specialization •Setae - chitinous bristles used for locomotion |
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Classes of Annelids
-divided by numbe of sentae |
Class Polychaeta-many setae: marine worms (Nereis)
Class Oligochaeta- few setae: earthworms Class Hirudinea - no setae: leeches |
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Parapodia
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foot function in locomotion and gas exchange
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Setae
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bristles Function in locomotion only!
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Class Polychaeta - 3
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•Many bristled setae
•Found on sea floor/reefs •Parapodia = external gills that provide extended skin surface area for gas exchange and function in locomotion |
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Class Oligochaeta: eathworms - 6
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•Few setae
•Longitudinal AND circular muscles •Long = shorten/thicken •Circ = elongate/thin •Gas exchange through skin –In dry spells head deep into soils –But rain they head towards surface to keep from drowning •Very complex organ systems •Clitellum present •Earthworm reproduction |
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longitudinal muscles earthworms
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shorten and thicken
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circular muscles in earthworms
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elongate and thin
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Nephridia (earthworms)
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paired excretory organs found along lateral margins; release waste fluids through small pores
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Earthworm mating - 4 things
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•Two hermaphroditic worms meet and line up with heads in opposite directions
–Held together by mucus secreted by the clitellum •Sperm from one worm is discharged and stored in the other worm’s seminal receptacle and vice versa •Worms separate and each secretes a mucus cacoon from clitellum that slides down body collecting eggs from egg sac and the other worm’s sperm from seminal receptacle •Fertilization occurs in cacoon, which is then deposited off anterior worm |
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Class Hirudinea
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•No setae!
•Includes leeches •High level of parental investment •Prior to incision secretes numbing anesthetic •“medicinal leech” –Relieve edema (swelling) during surgery |
