Mollusks  Phylum Mollusca  Coelomates- Have Coelom  More Than 110,000 Species  Survive on Land, Fresh and Marine Waters

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Mollusks Phylum Mollusca Coelomates- have coelom More than 110,000 species Survive on land, fresh and marine waters. Body Structure Bilateral symmetry Soft internal body Digestive tract, respiratory system, circulatory system and nervous system. Have a mantle; which is a membrane that surrounds the internal organs or mollusks. Mantle can secrete calcium carbonate to form a shell. Body structure Feeding and digestion Can be herbivorous, carnivorous or filter feeders. Radula- tonguelike organ with rows of teeth. Radula is used for scraping algae off rocks or to drill into other animals to feed on internal body parts. Have two openings to digestive tract. Have stomach and intestine Respiration Most mollusks have gills Gills- parts of the mantle that consist of a system of filamentous projections. used to transport oxygen into and to remove carbon dioxide from the blood. Move water through the mantle Increase surface area for gas diffusion Land snails and slugs take in oxygen using mantle cavities. Circulation Have a chambered heart Most mollusks have a open circulatory system Blood is pumped to open spaces surrounding body organs Utilized by slow moving animals (snails, slugs) Some mollusks have closed circulatory system Blood is confined to vessels as it moves through body Used by animals that move quickly (squid and octopus) Excretion Most mollusks get rid of metabolic waste through the nephridia. Nephridia- maintains homeostasis in body fluids. Response to stimuli Have nervous system that coordinates movement and behavior. Octopus have a brain and a complex eye. Movement Muscular foot is used for movement movement Squid and octopus use a siphon to move water into and then expel it out of the mantle. Reproduction Reproduce sexually Most release eggs and sperm into water at the same time. (external fertilization) Hermaphroditic mollusks use internal fertilization. All mollusks have a larval stage called a trochophore. Gastropods (Gastropoda) Stomach-footed mollusks Most have single shell Aquatic and moist terrestrial habitats Can draw their bodies into their shell when threatened. Slugs secrete mucus for protection Nudibranchs incorporate jellyfish nematocysts into their bodies after eating them; for protection Ex: snails, conches, periwinkles, limpets, cones. Bivalves (Bivalvia) Two shelled mollusks Most are marine Few found in freshwater Continuously filter feeding Ex: clams, mussels, oysters and scallops Cephalopods (Cephalopoda) Head-footed mollusks Foot is divided into arms and tentacles Have suckers; used to capture prey Most can expel ink when threatened Shells: Nautilus has external shell Squid and cuttlefish have internal shell Octopus has no shell Octopuses, squid and cuttlefish can change color for camouflage Nautilus can hide in its shell when threatened. .

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CHAPTER 10 MOLLUSCS 10.1 a Significant Space A
PART file:///C:/DOCUME~1/ROBERT~1/Desktop/Z1010F~1/FINALS~1.HTM CHAPTER 10 MOLLUSCS 10.1 A Significant Space A. Evolved a fluid-filled space within the mesoderm, the coelom B. Efficient hydrostatic skeleton; room for networks of blood vessels, the alimentary canal, and associated organs. 10.2 Characteristics A. Phylum Mollusca 1. Contains nearly 75,000 living species and 35,000 fossil species. 2. They have a soft body. 3. They include chitons, tooth shells, snails, slugs, nudibranchs, sea butterflies, clams, mussels, oysters, squids, octopuses and nautiluses (Figure 10.1A-E). 4. Some may weigh 450 kg and some grow to 18 m long, but 80% are under 5 centimeters in size. 5. Shell collecting is a popular pastime. 6. Classes: Gastropoda (snails…), Bivalvia (clams, oysters…), Polyplacophora (chitons), Cephalopoda (squids, nautiluses, octopuses), Monoplacophora, Scaphopoda, Caudofoveata, and Solenogastres. B. Ecological Relationships 1. Molluscs are found from the tropics to the polar seas. 2. Most live in the sea as bottom feeders, burrowers, borers, grazers, carnivores, predators and filter feeders. 1. Fossil evidence indicates molluscs evolved in the sea; most have remained marine. 2. Some bivalves and gastropods moved to brackish and fresh water. 3. Only snails (gastropods) have successfully invaded the land; they are limited to moist, sheltered habitats with calcium in the soil. C. Economic Importance 1. Culturing of pearls and pearl buttons is an important industry. 2. Burrowing shipworms destroy wooden ships and wharves. 3. Snails and slugs are garden pests; some snails are intermediate hosts for parasites. D. Position in Animal Kingdom (see Inset, page 172) E.
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SCI. MAR., 61 (Supl. 2): 5-14 SCIENTIA MARINA 1997 ECOLOGY OF MARINE MOLLUSCS. J.D. ROS and A. GUERRA (eds.) Biology and description of Antisabia juliae sp. nov., new Hipponicid gastropod commensal on Turbo spp. in Laing Island (Papua New Guinea)* MATHIEU POULICEK1, JEAN-CLAUDE BUSSERS1 and PIERRE VANDEWALLE2 1Animal Ecology Laboratory and 2Functional Morphology Laboratory, Zoological Institute, Liège University. 22, Quai Van Beneden, B-4020 Liège. Belgium. SUMMARY: The gastropod family Hipponicidae comprises widely distributed but poorly known sedentary species. On the beach-rock of the coral reefs of Laing Island (Papua New Guinea) live rich populations of several gastropod Turbo species of which many specimens have attached to their shell a hipponicid gastropod attributed to a new species, Antisabia juliae. This new species, described in this paper, appears to have adapted its mode of life on live turbinids in several ways result- ing in morphological changes (thin basal plate loosely adherent to the supporting shell, functional eyes, very long snout, functional radula, small osphradium) and ethological changes (foraging behaviour: it appears to feed on the epiphytic com- munity growing on the host, in the vicinity of the “host” shell). Except for these characteristics, the mode of life appears quite similar to that of other hipponicid species with few big females surrounded by several much smaller males. Development occurs within the egg mass inside the female shell and a few young snails escape at the crawling stage. Key words: Mollusca, Gastropoda, ecology, Hipponicidae, Papua New Guinea, Indopacific. RESUMEN: BIOLOGÍA Y DESCRIPCIÓN DE ANTISABIA JULIAE SP. NOV., UN NUEVO GASTERÓPODO HIPONÍCIDO COMENSAL DE TURBO SPP.
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Marine Boring Bivalve Mollusks from Isla Margarita, Venezuela
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Mollusca, Archaeogastropoda) from the Northeastern Pacific
Zoologica Scripta, Vol. 25, No. 1, pp. 35-49, 1996 Pergamon Elsevier Science Ltd © 1996 The Norwegian Academy of Science and Letters Printed in Great Britain. All rights reserved 0300-3256(95)00015-1 0300-3256/96 $ 15.00 + 0.00 Anatomy and systematics of bathyphytophilid limpets (Mollusca, Archaeogastropoda) from the northeastern Pacific GERHARD HASZPRUNAR and JAMES H. McLEAN Accepted 28 September 1995 Haszprunar, G. & McLean, J. H. 1995. Anatomy and systematics of bathyphytophilid limpets (Mollusca, Archaeogastropoda) from the northeastern Pacific.—Zool. Scr. 25: 35^9. Bathyphytophilus diegensis sp. n. is described on basis of shell and radula characters. The radula of another species of Bathyphytophilus is illustrated, but the species is not described since the shell is unknown. Both species feed on detached blades of the surfgrass Phyllospadix carried by turbidity currents into continental slope depths in the San Diego Trough. The anatomy of B. diegensis was investigated by means of semithin serial sectioning and graphic reconstruction. The shell is limpet like; the protoconch resembles that of pseudococculinids and other lepetelloids. The radula is a distinctive, highly modified rhipidoglossate type with close similarities to the lepetellid radula. The anatomy falls well into the lepetelloid bauplan and is in general similar to that of Pseudococculini- dae and Pyropeltidae. Apomorphic features are the presence of gill-leaflets at both sides of the pallial roof (shared with certain pseudococculinids), the lack of jaws, and in particular many enigmatic pouches (bacterial chambers?) which open into the posterior oesophagus. Autapomor- phic characters of shell, radula and anatomy confirm the placement of Bathyphytophilus (with Aenigmabonus) in a distinct family, Bathyphytophilidae Moskalev, 1978.
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Structure and Function of the Digestive System in Molluscs
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Egyptian Journal of Aquatic Biology & Fisheries Zoology Department, Faculty of Science, Ain Shams University, Cairo, Egypt. ISSN 1110 – 6131 Vol. 24(7): 531 – 551 (2020) www.ejabf.journals.ekb.eg Effect of probiotics on the growth performance and survival rate of the grooved carpet shell clam seeds, Ruditapes decussatus, (Linnaeus, 1758) from the Suez Canal Mahmoud Sami*, Nesreen K. Ibrahim, Deyaaedin A. Mohammad Department of Marine Science , Faculty of Science, Suez Canal University, Egypt. *Corresponding Author: [email protected] [ ARTICLE INFO ABSTRACT Article History: The carpet shell clam, Ruditapes decussatus is one of the most popular Received: Sept. 27, 2020 and commercially important bivalves in Egypt. This study aimed to evaluate Accepted: Nov. 8, 2020 the addition of probiotic to fresh algae, yeast and bacteria on growth Online: Nov. 9, 2020 performance and survival rates of the studied species. The experiment was _______________ performed in the Mariculture laboratory, at the Department of Marine Science, Suez Canal University, Ismailia, for 126 days from February 17th to Keywords: June 21th 2018. The experiments were implanted in seven square fiber glass Ruditapes decussatus; tanks with upwelling closed recirculating systems. Six diets were used in probiotic; this experiment in addition to a control. The growth performances were bacteria; determined by measurement of all biometric parameters including shell yeast; length, height, width, total weight, soft body weight and dry weight. The growth performance. highest specific growth rate and growth gain of shell length, height, width and total weight were recorded in diet F (mixed algae + probiotic) while the highest SGR and GG of soft weight and dry weight were recorded in diet D (bacteria + probiotic).
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