Mollusks with two shells are referred to as Bivalves Bivalves Two shells of a bivalve are hinged together at one end and are kept closed by a short tough ADDUCTOR MUSCLE Clams oysters and mussels have two adductor muscles ID: 1044704
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1. MollusksHave soft bilaterally symmetrical bodies composed of a head, foot, coiled mass of internal organs and most have either an external or internal shell.Mollusks with two shells are referred to as Bivalves
2. BivalvesTwo shells of a bivalve are hinged together at one end and are kept closed by a short, tough ADDUCTOR MUSCLE.Clams, oysters, and mussels have two adductor muscles.Mollusk shells are hard due to the presence of the compound CALCIUM CARBONATE.
3. How does a Bivalve build its shell?On the inside of the shell and around the internal organs is a protective membrane known as the MANTLE.Within the mantel are SHELL GLANDS that secrete CALCIUM CARBONATE to produce the shell.
4. How does a Bivalve eat if a shell surrounds it?Siphon Tube – Extends from one end of the shell to the other end and is exposed to the water when the shell opens.Incurrent siphon – WATER THAT CONTAINS FOOD AND OXYGEN ENTER HEREExcurrent siphon – WASTE PRODUCTS OF DIGESTION AND RESPIRATION ARE ELIMINATED HERE. Since bivalves filter their food from the water, they are examples of FILTER FEEDERS.
5. Life Activities of BivalvesBivalves are adapted to breathe underwater by using GILL MEMBRANES.Water brought in through the incurrent siphon flows over the gills.The surface of the gills contain specialized cells with MICROSCOPIC CILIA.The ciliated cells help to move the water through the clam and over the gills. Once over the gills, OXYGEN diffuses from the water and into the gills while CARBON DIOXIDE diffuses from the gills to the water and is removed out through the EXCURRENT SIPHON.
6. How does a Bivalve eat?Water that enters the incurrent siphon contains PLANKTON and ORGANIC DEBRI.The food particles get stuck in the MUCUS that coats the surface of the gills and mantle.The ciliated cells move the food to the clam’s mouth where food is digested in the digestive tract and removed by the excurrent siphon.
7. Adaption's to aid certain bivalves with feeding include:Tough BYSSAL THREADS with sticky pads that allow them to bind to hard substrates. (EX. MUSSELS)Oysters can secrete a CEMENT to help them bind to a substrate.
8. How do oysters make pearls?A pearl is a small, round, shinny bead that has the same composition as the smooth interior lining of the shell.A natural pearl begins to develop when a SAND GRAIN gets into an oyster and lodges between the mantle and the shell.The mantle tissue reacts to the sand grain as a FOREIGN BODY and secretes layers of shell around the grain forming a PEARL.
9. Movements in BivalvesFastest moving bivalve is the SCALLOP (also have about 60 blue eyes for sensing) The fan-shaped mollusks move across the seafloor in sudden spurts.Quick movements are caused by repeated contraction and relaxation of the large adductor muscle, by opening and closing.
10. Other Bivalves move through Substrates (EX. Sand and MUD)Bivalves such as RAZOR CLAMS and SOFT-SHELLED CLAMS use their muscular foot to dig.Shipworms can bury through solid substrates such as pilings (bulkheads) thus causing large amounts of damage.
11. Reproduction in BivalvesBivalves have separate sexes:FEMALES: release their eggs into the water.MALES: release their sperm to fertilize eggs.In the early stages of development, the bivalves exist as part of the PLANKTON community.Eventually, the tiny bivalves develop their shells and sink to the bottom and mature into adults.
12. Best ways to study Bivalves!!!On a plate with a fork!
13. GastropodsDiverse group of mollusks, that make up 2/3 of all mollusks that are referred to as UNIVALVES meaning, “ONE SHELL”The most common type of gastropods are SNAILS.
14. Gastropod AnatomySiphon – the snail breathes by taking in oxygenated water through its siphonGills – gas exchange; O2 in and CO2 out.Anterior Tentacles – uses for the sensation of touch.Posterior Tentacles – used for vision.Radula – a tooth-like structure that scrapes off and ingests algae from substrates (hard surfaces).
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16. Feeding in SnailsMost snails move along the seafloor, where they graze on tiny organisms.The PERIWINKLE grazes on ALGAE that grows on the surface of substrates such as rocks and marsh plants.
17. Cephalopods-class with many species that do NOT have a shellRefers to the class of swimming mollusks that use JET PROPULSION.How are cephalopods adapted for swimming?Stream-lined body shapeLack an external shell.Water is expelled through the siphon
18. Life Activities in the Cephalopods?Cephalopods capture prey, such as fish and crabs by using its TENTACLES and its parrot like beak.Octopuses secrete its paralyzing venom into its prey when it is bitten. The octopuses also uses their tentacles to capture prey and bring it to the mouth.One species of octopus uses it tentacles to crawl on land and search for food on the shore.
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20. How are squids and octopuses protected without an external shell?1. The squid is the fastest of all the cephalopods. 2. Squid live in large schools. Octopus live alone they are the most intelligent cephalopod and have great eyesight. 3. Camouflage – (octopus) specialized pigmented cells in the skin called chromatophores, change skin color and patterns to match it background.4. Discharge a thick cloud of ink – used to surprise and confuse predators to allow the cephalopod to escape.
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22. Other types of CephalopodsChambered NautilusCuttlefishChief Squid
23. Reproduction in CephalopodsSeparate sexes where fertilization is INTERNAL and development is EXTERNAL.Male delivers a sperm into the mantle of the female with the use of a tentacle.Most squid die after mating and leave the egg to develop on their own.The female dumps the eggs on rocks until they hatch.
24. Differences between squid & Octopus Squid Octopus10 tentacles 1. 8 tentaclesSuction disks used 2. suction disks used for grasping for climbing and crawling3. Live in groups 3. live alone4. Die after eggs are 4. Die after eggs hatchFertilized
25. Video clipshttps://www.youtube.com/watch?v=QzT2L5CsiA8 scallops moving 38sechttps://www.youtube.com/watch?v=_2iXHBuSIJY 54sec scallop moving https://www.youtube.com/watch?v=tIOSWAbUf74 pearl formation 2:28 minhttps://www.youtube.com/watch?v=UEZrgcLqVaM pearl farming 3:55 minhttps://www.youtube.com/watch?v=SWRpQlh_Qu0 blue point oysters
26. https://www.youtube.com/watch?v=949eYdEz3Es octopus moving through small hole 50 sechttps://www.youtube.com/watch?v=yrv4-EFBa5w 2 min seal vs octopushttps://www.youtube.com/watch?v=p9A-oxUMAy8Octopus vs shark national geographic 2:50 minhttps://www.youtube.com/watch?v=om9iq4mo9fI blue ring octopushttps://www.youtube.com/watch?v=3k-5GSOsxBg cone snail bite 4:11 minhttps://www.youtube.com/watch?v=qyVQqs2rykg 1:20 min giant squidhttps://www.youtube.com/watch?v=jCWop491Q9Y 2:31 min live footage in submersible giant squid
27. Know the differences between Squid and Octopus.&Octopus facts