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Bio Concepts 2 lab
excercise 11 The Molluscs
| Term | Definition |
|---|---|
| What do they include? | Chiton, snails, slugs, clams, oysters, squids, octopuses, cuttlefish |
| Their retained basic features include | triploblastic structure, bilateral symmetry, cephalization, body cavity, true coelom |
| What is the trochophore ancestral trait | spiral cleavage |
| what does Mollusca mean | soft body |
| Muscular foot | used for locomotion |
| Mantle | two folds of the skin from the dorsal body wall form a protective structure. may secrete a protective shell |
| Mantle cavity | encloses a space between the mantle and body wall. houses the gills |
| Where are freshwater clams found | fresh and salt water, partly or wholly buried in sand. their reactions are slow. |
| When clams move they... | leave a furrow in the sand when it moves |
| exoskeleton | protects the soft body. made of a pair of valves(shells) hinged on the dorsal side. |
| when the clam is at rest... | the valves are slightly open and you can see at the posterior end the edges of the mantle, which lines the valves |
| the posterior edges of the mantle are shaped so... | as to form two openings (apertures) to the inside of the mantle cavity. |
| why a steady flow of water is important for clams | necessary to bring oxygen and food to the animal and carry away waste. Filter feeders via ciliary action to the mouth. |
| Siphons | when clams have the mantle drawn out long and muscular. when the animal burrows this extends up to the surface to bring clear water to the mantle cavity. |
| clams foot | soft, flexible and sensitive |
| Hinge ligament | attaches the two valves of the clam on the dorsal side. the ventral side is free for the protrusion of the foot. |
| umbo | swollen hump near the anterior end of the hinge is the oldest and thickest part of the shell and the part most resistant to predators. |
| lines of growth | around the umbo indicate growth periods |
| Periostracum | outer horny layer of the shell. protects the underlying calcium carbonate from being dissolved in the acid water.thin and tends to worn away from older parts of the shell |
| nacreous layer | lies next to the mantle and is secreted continuously by the mantle surface. |
| prismatic layer | between the inner nacreous layer and outer periostracum. made of crystalline calcium carbonate.secreted by glands in the edge of the mantle. |
| hinge ligaments | acts as a spring to force the shells apart |
| anterior and posterior adductor muscles | pull the shells closed. |
| Pallial line | marks the location of the pallial muscle that retracts the edge of the mantle. |
| Hinge teeth | a ridge on the lateral side that interlock the valves to prevent them from slipping apart. |
| incurrent and excurrent apertures | permit continuous flow of water through the mantle cavity. |
| the clams outer fold | secretes the horn like prtiostracum as well as the prismatic layer of the shell. |
| Middle lobe is what... | the sensory location. drawn out into specialized sensory structures.tenticles and eyes. |
| Ciliated surface of the inner fold | assists in water circulation within the mantle cavity and sweep out debris. seals the mantle cavity,form the clams incurrent and excurrent apertures |
| in muscles the adductor muscle | closes the valves |
| Foot retractor muscles in muscles | small and will be found lying in the visceral mass just posterior to the anterior adductor. |
| Pericardium | dorsal side. Pericardium membrane surrounds the heart |
| Mantle cavity | entire space between the right and left lobes of the mantle. cilia on mantle and gills keep water flowing through this. |
| brood chamber | where embryos develop |
| Visceral mass | soft portion of the body |
| Foot of clam is a what | muscular hydrostat |
| labial palps | pair on each side of the body. serve as guide for food particles trapped In mucus into the mouth. |
| Clams are filter feeders that depend on | highly modified gills to gather food materials as well as respiration. |
| Gill filaments | draw water in the incurrent siphon then into water tubes through numerous tiny pores between the gill filaments |
| suprabran chial chamber | connects the water tubes dorsally in turn emptying to the outside through the excurrent aperture. |
| water tubes on females | serve as brood pouches for eggs or larva during breeding season |
| Pericardial sac | contains the heart. |
| The clam heart | three chambered;single ventricle,pair of auricles. ventricle surrounds the intestine |
| anterior aorta | passes the visceral mass and intestine |
| posterior aorta | runs along ventral side of rectum to the mantle. |
| coelomic cavity | space around the heart.small. |
| molluscs circulatory system | open, no capillaries, sinus are narrow clefts and channels in connective tissue surrounding the muscular and nervous tissues. |
| molluscs excretory system | pair of kidneys, get waste from blood vessels.waste is discharged into the superabtanchial chamber and carried away by exhalant current. |
| gonad | brown tissue that surrounds the intestine. sex cells. discharge products into suprabranchial chamber. enter female through inhalant current |
| crystalline style | gelatinous rod that projects into the stomach. composed of mucoproteins and digestive enzymes that are released into food. |
| glochidium | where the zygote develops. lives as parasite for several weeks. |
| clams nervous system | not highly centralized. three pairs of ganglia, cerebropleural ganglia,pedal ganglia,visceral ganglia |
| ganglia | small groups of nervous cells |
| cerebropleural ganglia | found on each side of esophagus on the posterior surface of the anterior adductor muscle |
| pedal ganglia | fused and are found in the anterior part of the foot. |
| visceral ganglia | fused into a star shaped body just ventral to the posterior adductor muscle. |
| sense organs in clams | poorly developed. touch, chemical sensitivity, balance, light sensitivity. most abundant of the edge of the mantle. |
| radula | series of tiny teeth attached to a ribbon like organ that moves rapidly back and forth |
| whorl | 1 complete spiral turn on the shell. lines of growth |
| pneumostome | mouth, connects to lung. diffusion of gasses between air and water occur |
| chiton movement | stay still during the day. move at night be return to exactly the same spot. adhere tightly to rocks. |
| chiton feeding | scraping algae and diatoms from rocks. |
| girdle | thick and leathery margin of the mantle. partly covers the dorsal plates. |
| snail have subradular organ | extend form the mouth and is thought to be taste organ (chemosensory) |
Created by:
ejohnson17
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