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Zoology, lecture XX
Invertebrates: Mollusca
Question | Answer |
---|---|
Mollusca | תוכיכר Between 50-100 thousand living, 35,000 fossilized species. Large and varied phylum of organisms with a lot of significance. |
Mollusca characteristics | Soft body usually bilateral symmetry, Mantle, shell, radula, muscular leg, sensory organs, both dieocious and monoeicous representatives |
Mantle | המילג aka pallium, it is the dorsal body wall that covers the visceral mass and in many species secretes calcium carbonate and conchiolin producing the shell. |
Mantle adaptations and uses | It has grown into a variety of functions including siphons used for respiration. |
Radula | Scraper-a ribbon like organ that is lined with teeth and used for scraping the food and bringing it to the esophagus. |
Mollusca sensory organs | |
Mantle cavity | Formed by the mantle skirt--a double fold of mantle which encloses a water space containing the mollusc's gills, anus, osphradium, nephridiopores and gonopores. It's a respiratory chamber in all molluscs (in some broom/locomotion) |
What do molluscs eat? | A whole range of everything. |
Where do mollusks live? | Marine, freshwater, land and even desert! There are benthic and pelagic representatives, sessile and free swimming representatives. |
Phylum characteristics of mollusks | A compact coelom, protostomia, bilateral symmetry, nonsegmented body, Digestive/sensory systems, usually open circulatory system, gas exchange through gills. |
Mollusk structure | They have two body segments: לגר-שאר for eating, sensing, moving, and the םייברק קש mantle cavity contains digestive, circulatory, excretory and reproductive organs, mantle=respiration |
Radula structure and function | It operates with the help of muscles that are supported by cartilage called the odontophore. The teeth wear down and grow back in. |
Odontophore | Cartilaginous supporting structure of the radula. |
How do molluscs move? | Crawling, swimming, jumping, sticking. Some are sessile, some use תינוליס squirting using their siphons to move along like a jet |
Muscular leg structure and function | Locomotion, digging, crawling, swimming and sticking. It functions through waves of contractions of muscles. Function through haemocoel |
Hemocoel | A series of spaces between the organs of organisms with open circulatory systems. Its a combination of blood lymph and interstitial fluid called hemolymph that circulates through hemocoel. |
Mantle/cavity structure and function | Dorsal skin folds produce the mantle. The cavity is the space between the mantle and the wall of the body, gas exchange through ctenidiae gills or lungs, reproductive and digestive secretions are released into the cavity. |
Ctendidiae | A comblike respiratory apparatus that functions like a gill in mollusks |