Mollusks Have soft bilaterally symmetrical bodies composed of

Mollusks Have 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

Bivalves Two shells of a bivalve are hinged together at one end 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.

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.

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 HERE Excurrent siphon – WASTE PRODUCTS OF DIGESTION AND RESPIRATION ARE ELIMINATED HERE. Since bivalves filter their food from the water, they are examples of FILTER FEEDERS.

Life Activities of Bivalves �Bivalves 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.

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.

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.

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.

Movements in Bivalves Fastest 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.

Other Bivalves move through Substrates (EX. Sand 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.

Reproduction in Bivalves 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.

Best ways to study Bivalves!!! On a plate with a fork!

Gastropods Diverse 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.

Gastropod Anatomy Siphon – the snail breathes by taking in oxygenated water through its siphon Gills – gas exchange; O 2 in and CO 2 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).

Feeding in Snails Most 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.

Cephalopods-class with many species that do NOT have a shell Refers to the class of swimming mollusks that use JET PROPULSION. How are cephalopods adapted for swimming? Stream-lined body shape Lack an external shell. Water is expelled through the siphon

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 search for food on the shore.

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.

Other types of Cephalopods Chambered Nautilus Cuttlefish Chief Squid

Reproduction in Cephalopods Separate 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.

Differences between squid & Octopus Squid 1. 10 tentacles 2. Suction disks used for grasping 3. Live in groups Octopus 1. 8 tentacles 2. suction disks used for climbing and crawling 3. live alone 4. Die after eggs are Fertilized 4. Die after eggs hatch

Video clips https: //www. youtube. com/watch? v=Qz. T 2 L 5 Csi. A 8 scallops moving 38 sec https: //www. youtube. com/watch? v=_2 i. XHBu. SIJY 54 sec scallop moving https: //www. youtube. com/watch? v=t. IOSWAb. Uf 74 pearl formation 2: 28 min https: //www. youtube. com/watch? v=UEZrgc. Lq. Va. M pearl farming 3: 55 min https: //www. youtube. com/watch? v=SWRp. Qlh_Qu 0 blue point oysters

https: //www. youtube. com/watch? v=949 e. Yd. Ez 3 Es octopus moving through small hole 50 sec https: //www. youtube. com/watch? v=yrv 4 -EFBa 5 w 2 min seal vs octopus https: //www. youtube. com/watch? v=p 9 A-ox. UMAy 8 Octopus vs shark national geographic 2: 50 min https: //www. youtube. com/watch? v=om 9 iq 4 mo 9 f. I blue ring octopus https: //www. youtube. com/watch? v=3 k-5 GSOsx. Bg cone snail bite 4: 11 min https: //www. youtube. com/watch? v=qy. VQqs 2 rykg 1: 20 min giant squid https: //www. youtube. com/watch? v=j. CWop 491 Q 9 Y 2: 31 min live footage in submersible giant squid

Know the differences between Squid and Octopus. & Octopus facts