Lecture 4 DA Flashcards
What is the feeding organ of molluscs?
Radula and odontophores.
Where is an odontophore relative to a radula?
The odontophore projects out of the mouth, and the radula slides over it.
What two functions do feet have?
Burrow into the substratum or for locomotion.
How can feet be used for burrowing?
Burrows into the substratum, and the ends thicken to anchor.
What is a mantle? What happens here in shelled organisms?
Sheath of skin on each side on the body. Shell is secreted here in shelled organisms.
What does the mantle cavity house? What function does it have if exposed?
Gills or lungs. Has gas exchange function if exposed.
Where do products of digestive, excertory and reproductive systems empty to?
The mantle cavity.
What use do mantle cavities have in cephalopods?
Jet propulsion.
What are the layers of a shell and what are they made of (3)?
Periostracum - outer horny layer, made of conchiolin.
Prismatic layer - middle layer, made of closely packed CaCO3.
Inner layer - nacreous layer, made of nicre.
What is conchiolin?
Tanned protein.
What are ctenidia, and where are they housed?
They are gills created by overhanging mantle and shell.
Several pairs are housed in the mantle cavity.
Composed of numerous flattened filaments extending from a support axis - looks like a TV antennae.
How does water move over ctenidia?
Has leaf-like filaments with cilia to draw water across.
Do molluscs have countercurrent blood movement?
Yes.
Do molluscs have a pumping heart and blood vessels?
Yes.
What are haemocoeles?
Blood sinuses in molluscs.
What is the excretory organ of molluscs?
Pair of kidneys or metanephridia.
How do molluscs discharge gametes?
Via their kidney duct.
What is the nervous system of molluscs like?
Mantle and visceral mass innervated by a pair of nerve cords, and its foot by another pair.
What do the pedal and visceral nerve cords innervate?
Pedal - Foot
Visceral - Mantle
Do the pedal and visceral nerve cords communicate, or are they independent?
They do, the connections make it look like a ladder.
What kinds of highly specialised organs can molluscs have (3)?
Eyes, statocysts and osphradia (chemoreceptor patches).
What is the stomach of molluscs like?
Has a primitive stomach that processes fine particles of food.
What is a protostyle? How is it used?
A rotating mucous mass in the style sac. A crystalline style within the sac pulls on the mucus with food in it, which is filtered off and sent to digestive glands.
Are molluscs monoecious?
No, diecious.
Where are the mollusc’s gonads found? How many do they have?
A pair is found near the visceral mass, near the pericardium.
Where are gametes released into?
The coelom, from the kidney duct, called gonaduct.
What kind of cleavage do molluscs have?
Spiral cleavage, whatever the fek that means.
What is a trochophore?
First larval stage of molluscs.
What is a veliger? Is this found in other phyla aside from molluscs?
It is the second larval stage, and is unique to molluscs.
What are the classes of molluscs (8)?
Caudofoveata Solenogastres Monoplacophora Polyplacophora Scaphopoda Gastropoda Bivalvia Cephalopoda
What classes of molluscs are worm-like? What water environment do they live in? What features do they have?
Caudofoveata
Solenogastres
They are 5mm and live in deep ocean water.
What classes of molluscs have poorly developed heads and no shells? What do they feed on?
Caudofoveata
Solenogastres
Feed on cnidarians.
Are Caudofoveata monoecious? What about Solenogastres?
Caudofoveata are diecious.
Solenogastres are monoecious.
What is a distinguishing feature of Solenogastres?
Theyre monoecious.
Where do monoplacophora live?
Deep ocean.
Are monoplacophora shelled? What shape do they have?
Yes, theyre shield shaped.
What do monoplacophora look like? What ar etheyr internal and external structures like?
Look like limpets, but arent. Have a repetition of internal and external structures, ie multiple sets of gills and kidneys etc.
What do monoplacophora use their foot for?
Creeping.
Are monoplacophora cephalised?
Slightly.
Do monoplacophora have a stomach and radula?
Yes, and a cone shaped stomach.
What do monoplacophora feed on?
Diatoms and sponges.
Which class are chitons found in, and what are they?
Class polypacophora. They are plates adapted for hard surface living.
Where do polypacophora live?
Hard surfaces, especially intertidal zones.
What is the periphery of polypacophora mantles called?
Girdle.
How do polypacophora lock themselves down?
Their mantle is thick and stiff. It extends beyond the lateral margins of the chitons. It and the foot are used for gripping.
How many plates do polypacophora have?
8 articulating plates.
Do polypacophora have eyes or tentacles?
No.
Do polypacophora have a distinct head?
No.
What do polypacophora feed on and how?
Fine algae using very long radula.
What is a pallial groove in polypacophora?
Groove between the mantle and foot housing multiple gills.
Are polypacophora diecious? Where are their gonads found?
Are diecious. Has a single medial gonad.
Where does fertilisation occur in polypacophora?
In the ocean or female mantle.
How are polypacophora eggs protected?
Enclosed in a spiny envelope.
Do polypacophora have a veliger and trochophore stage?
Has a trochophore stage only, with no veliger stage.
No trochophore stage as well in those that brood eggs (egg fertilised in female mantle).
Where do scaphopoda live?
Burrowing marine.
What shape do scaphopoda have? Are they shelled?
Shelled, and tusk shaped.
How do scaphopoda burrow?
Burrows in soft bottoms, shell open at each end, wider end is burrowed, where the foot is. Ventilating current enters and leaves through the small hole.
What do scaphopoda feed on?
Detritus, and protozoa.
What are captacula?
Mucus covered cilia used by scaphopoda to feed.
Do scaphopoda have radula?
Yes.
What is the largest class of molluscs?
Gastropoda.
Gastropods have torsion and spiral shells. What is a consequence of this?
Right gill, auricle, and nephridium is reduced or lost.
Name 4 ways in which gastropods are diistinct from generalised molluscs.
- Developed head
- Dorsoventral elongation
- Shell converted from protective shield to protective housing
- Torsion, body twisted 180* counterclockwise.
What is a benefit of torsion in gastropods?
Digestive system twists with it, and the anus twists upward, allowing it to discharge out of the shell, versus into the mantle cavity.
When does torsion in gastropods occur?
Typically in veliger stage.
What are columella muscles used for?
Withdrawing head and foot into the sheel, gastropods.
What are the three subclasses of gastropoda?
Prosobranchia
Opisthobranchia
Pulmonata
What is the operculum, and what is it found in?
Horny disc that acts as a hinge with the foot, allowing it to seal the aperture. Found in the gastropod subclasses Prosobranchs, opisthobranchs, and pulmonates.
Do prosobranchia have torsion, and how do they breathe?
Respire by gills, and have torsion.
Do opisthobranchia have torsion, a shell and a mantle cavity?
Has detorsion.
Shell and mantle cavity is reduced or absent.
Do pulmonata have gills and torsion? What is their mantle cavity like?
No gills, replaced by lungs in the mantle cavity. Has some detorsion.
What is the order in prosobranchia called?
Archaeogastropoda.
What is the most basal of gastropod forms?
Archaeogastropoda.
How is waste removed in archaeogastropoda?
Shell has notches or perforations that allow waste product removal.
Where do archaeogastropoda live?
Restricted to firm substrata.
Do prosobranchia have monopectinate or bipennate gills?
No right gill, their single left gill is monopectinate.
Are prosobranchia restricted to hard surfaces?
No, only the order archaeogastropoda are.
Are both freshwater ans terrestrial prosobranchia operculate?
Yes.
Do prosobranchia have probuscises?
Yes, in carnivorous species.
How do prosobranchia reproduce?
Most copulate, with internal fertilisation.
Do prosobranchia have trochophore and veliger?
No trochophore stage, hatches direct to veliger.
Called direct development.
Where do opisthobranchia live?
Marine.
What degree of torsion do opisthobranchia have?
90*
Where is the gill and mantle cavity of opisthobranchia located?
Right side.
Do opisthobranchia have an operculum?
No.
Are opisthobranchia shelled?
Some have primitive shells, lost in many,same with gills.
Are opisthobranchia monoecious?
Yes.
Do opisthobranchs have a trochophore and veliger stage?
Veliger only, direct development.
What degree of torsion do pulmonata have?
90*
Do pulmonata have gills? Where do they live?
Gill is lost, mantle cavity became a lung.
Lives in intertidal zones, as well as terrestrial.
Basal forms live in freshwater.
Do pulmonata have tentacles or eyes?
Higher ones have tentacles with eyes on them.
Are pulmonata monoecious? How do they reproduce?
Yes. Copulate for mutual sperm transfer.
Do pulmonata have direct development?
Yes,
Where are the digestive organs of pulmonata found?
Upper shell.
What are the three major groups of class bivalvia, and how are they distinguished? Which is the majority?
Protobranchs
Lamellibranchs - majority
Septibranchs
Which end are bivalvia joined? Do they have a prominent or reduced head?
Shells join at the dorsal end, and have a reduced head.
What are the foot and gills in bivalvia like?
Foot is compressed laterally.
Gills are large with food collecting role.
Do bivalvia have radula?
No.
Can bivalvia burrow?
Yes, in soft substrata.
Which group are primitive bivalvia in?
Protobranchia.
Are protobranchia gills bipennate or monopectinate?
Bipennate.
Where does the ventilating current enter and leave protobranchia?
Posterior end.
How do protobranchia feed?
Are selective feeders.
Use a pair of palpal tentacles.
Stomach has a protostyle and sorting reigon.
Inner surface of palps are ciliated and ridged.
Light particles are carried by crest cilia, heavy by groove cilia.
What do crest and groove cilia in protobranchia carry?
Crest - light particles to the mouth.
Groove - heavy particles to the mantle.
What do lamellibranchia use their gills for?
Gas exchange and filterfeeding.
What do frontal cilia in lamellibranchia do?
Transport food particles.
How do lamellibranchia filter food?
Have lengethened and folded gill filaments for greater surface area.
Forms grooves for food transport.
Water in the inhalant chamber circulates between ridges, entering a water tube via ostia.
Water flows out of the exhalant opening via water tubes.
How do lamellibranchia digest?
Their stomach protostyle consolidates into a gelatinous crystalline style, liberates enzymes at its eroded.
What are lamellibranchia diverticula?
Allows intracellular digestion of proteins to follow extracellular digestion of starches and lipids in the stomach.
What are infauna and epifauna?
Epifauna - attached or unattached surface dwellers
Infauna - soft bottom burrowers.
Where do epifauna lamellibranchia live?
Hard surfaces by threads called byssal threads or cementation onto hard surfaces.
Do epifauna lamellibranchia have a foot?
No, they tend not to have one.
Do epifauna lamellibranchia have strong anterior adductor muscles? What does it do?
It is reduced. Closes the shell.
Are epifauna lamellibranchia symmetrical?
No.
What is escape swimming?
Propulsion by clapping their shells,done by epifauna lamellibranchia.
What are boring bivalves?
Epifauna lamellibranchia that can drill, done mechanically using anterior shell margins.
Are bivalvia diecious or monoecious?
Mostly diecious.
Do bivalvia have trochophores and veligers? Where does fertilisation occur?
Fertilisiation is usually external.
Has both trocophore and veliger larvae.
Development is planktonic.
How do cephalopod swim?
Jet propulsion.
How do some cephalopods control buoyancy? What is a consequence of this?
Has a gas filled chamber, regulated by controlling volume wthin. Chamber is called siphuncle, and are slow swimmers. Usually have a shell.
What are chromatophores?
Skin colour changing cells found in some cephalopods.
Can cephalopods see colour?
No, theyre colour-blind.
Do all cephalopods produce ink?
Yes, all except shelled.
Are cephalopods benthic?
Yes, they have secondary crawling for locomotion. Jet propulsion only for escaping and intermittent swimming.
Are cephalopods diecious?
Yes, all are.
How do cephalopods reproduce?
Male rips off a spermatophore from its mantle and inserts it into a female’s mantle cavity using a single arm called hectocotylus.
Do cephalopods have direct development?
Yes, but some young are planktonic.
Do cephalopods have prehensile tentacles?
Most do, theyre held by 8 arms. All have suckers.
Do octopods have tentacles?
No, due to crawling, but still have the arms.
What are the mouths of cephalopods like?
Horny parrot-like beak with a pair of poison glands.
How do cephalopods eat?
Grasp prey and tear off pieces using radulae.
What oxygen-carrying protein do cephalopods use?
Haemocyanin.
Are cehalopod gills ciliated?
No.
Do cephalopod gills have secondary folding?
Yes.
Do cephalopods have eyes?
Yes, highly developed eyes.
