What is the name of the phylum including class gastropoda, class pelecypoda, class cephalopoda?
What are the classes of Phylum Mollusca?
1. Class Gastropoda
2. Class Pelecypoda
3. Class Cephalopoda
What are the means of Class Gastropoda?
What are examples of Class Gastropoda?
What are the means of Class Pelecypoda (or Bivalvia)?
1. Hatchet foot
2. Two shells
What are examples of Class Pelecypoda (or Bivalvia)?
What are the means of Class Cephalopoda?
What are examples of Class Cephalopoda?
What are the key evolutionary advances?
2. First phylem that has all major systems present
What is the habitat of Phylum Mollusca?
Everywhere but dry environments.
What is the general body plan of Phylum Mollusca?
What are the body regions of Phylum Mollusca?
3) Visceral Mass
What is the variety of feeding methods of Phylum Mollusca?
3. Filter feeders
What is the size of Phylum Mollusca compared to Arthropods?
One of the largest animal phyla after Arthropods.
How many living species are there of Phylum Mollusca?
Nearly 50,000 living species.
How many fossil species is there of Phylum Mollusca?
35,000 fossil species.
What do Phylum Mollusca fossils indicate?
Origination in the seas along the shores.
How do Phylum Mollusca range in size from?
Almost microscopic to 18m long (80% are less than 5cm in maximum shell size).
What do most Phylum Mollusca have in regards to circulatory system?
An open circulatory system with pumping heart, vessels and blood sinuses (Cephalopods have a closed system)
Where does gas exchange take place in Phylum Mollusca?
Across the body surfact along with either lungs or gills.
What does the body plan of Phylum Mollusca consist of?
2. Visceral mass
What kind of organs does the head/foot of Phylum Mollusca contain?
2. Cephalic sensory
What does the head/foot of Phylum Mollusca depend on?
The action of muscular contraction to function.
What kind of organs does the visceral mass of Phylum Mollusca contain?
What does the visceral mass of Phylum Mollusca depend on?
The action of ciliary movements to function (they have various ciliary tracts).
Describe the head of Phylum Mollusca.
Well-developed heads with a mouth and a radula.
A rasping tongue like organ (not found in bivalves). A ribbon membrane covered with rows of tiny backwards-pointing teeth.
What does the radula serve to do?
Scrape off food and provides a "conveyer belt" to transport food toward the digestive tract.
Where are worn teeth of Phylum Mollusca replaced?
How are the pattern and number of teeth in Phylum Mollusca?
Species specific and it is used in classification.
What are some types of radulas specialized for?
What are foot functions?
5. Predatory action
Where is the foot usually in Phylum Mollusca?
Ventral, in bivalves it is a lateral hatchet foot and in cephalopods it is divided into tentacles.
What does the mucous of the foot of Phylum Mollusca aid in?
What is foot extension in snails and bivalves by?
Body hydraulics (lined with blood).
What is the visceral mass sometimes called?
The visceral hump.
Fleshy layer of tissue that is formed from the dorsal body wall. It surrounds the mantle cavity which houses the gills or lungs if they are present and its surface may assist in gas exchange.
What does the mantle also secrete?
The shell in those forms that possess one.
What type of organs develop from the mantle?
The respiratory organs, which serves for gas exchange and have receptors for sensing chemicals in the water.
What does the mantle cavity create in cephalopods?
High water pressure that it uses as a type of jet propulsion.
What may the mantle cavity may be divided into?
An excurrent and an incurrent chamber with gills.
How many layers is the shell formed of?
When does the first shell appear?
During the larval period.
What are the three layers of shell?
Outer horny layer, growth occurs at margin of shell, forms ligament that attaches the two halves.
Crystals of calcium carbonate arranged perpendicular to the other layers.
Inner layer, lies next to the mantle and is secreted continuously by the mantle. It increases in thickness over time, laid down parallel to the shell, called the mother of pearl layer.
Where does the calicium in the shell of Phylum Mollusca come from?
Enviornmental water, soil or food.
What does the nervous system of Phylum Mollusca consist of?
Several pairs of ganglia with connecting nerve cords and neurosecretory cells that produce growth hormone and function in osmoregulation.
Describe reproduction of Phylum Mollusca (monoecious or dioecious).
Most are dioecious but some are hermaphroditic.
What are reproductive developmental stages of Phylum Mollusca varied among?
A number of molluscs have a free-swimming, ciliated larva called what?
What are trocophores also?
A larval stage of annelids, indicating an evolutionary relationship between annelids and molluscs.
Where does the trocophore develop in bivalves and gastropods?
Within the egg and a veliger (which has the beginnings of a foot, shell and mantle) hatches to become the only free-swimming form.
What hatch directly from eggs?
Cephalopods, freshwater, and some marine snailes, and some freshwater bivalves.
The stomach footed molluscs.
What are examples of Class Gastropoda?
6. Sea slugs
What is the largest and most diverse class of mollusks?
How many living and fossil species are there of Class Gastropoda?
40,000 living and 15,000 fossil species.
What are food sources of Class Gastropoda?
2. Lang vegetation
3. Small invertebrates
What are the nutritional modes of Class Gastropoda?
What does the radula of Class Gastropoda act as?
A scraper like file or drill with tiny chitinous teeth.
What can some species of Class Gastropoda deliver with their radulas?
Painful stings with venom (can be lethal to humans).
What do some Class Gastropoda use their radula for?
To bore through the shells of clams.
Where is the mantle cavity found in Class Gastropoda?
Anteriorly, usually behind the head slightly off center.
Where does most respiration take place in in Class Gastropoda?
In the mantle cavity, either directly through mantle tissue, or through lungs or gills that have developed within the cavity itself.
Where does the anus open at in Class Gastropoda?
At the outside edge of the mantle cavity.
Class Gastropoda have a single shell and it is their chief form of defense.
A hard mucous plug that drys out and protects gastropods from dessication.
Twisting the visceral mass so the anus is above the head.
When does torsion occur during in Class Gastropoda?
The veliger stage, and only Gastropods exhibit torsion.
What problem does torsion create for gastropods, and how is it solved?
Not pooping on their head.
What forms before torsion takes place in Class Gastropoda?
A coiled (spiraled) shell.
What is the direction of coiling?
What two directions of coiling is there?
Right handed coiling (most common).
Left handed coiling.
Are coiling and torsion the same thing?
Describe the nervous (sensation) of Class Gastropoda.
Well-developed head with ganglia.
What are the sensory organs of Class Gastropoda?
3. Tactile organs
Where are the eyes of Class Gastropoda?
At the tips of each tentacle (vision) or simple photoreceptors (light and dark).
Detect balance in gravity.
Detect touch and feeling.
Detect smell and taste.
Describe the movement of Class Gastropoda.
Broad, flat, creeping foot.
What is the foot of Class Gastropoda propelled by?
Muscular peristalsis of foot and mucous secreted by gland cells.
Describe excretion of Class Gastropoda.
Have a single kidney (nephridia) for filtering out wastes from bodily fluids and excreting them via pores.
Are seperate sexes common in Class Gastropoda?
Yes, but some are hermaphroditic.
How is fertilization in Class Gastropoda?
Internal, achieved through copulation.
Hard rigid structure protruding from the head that stabs the other gastropod in the brain so they don't kill sperm cells.
The hatchet footed mollusks.
Class Pelecypoda (bivalvia)
What are examples of Class Pelecypoda (bivalvia)?
Describe the generic characteristics of Class Pelecypoda (bivalvia).
1. Hatchet footed, two shells also called bivalves.
2. No head, no radula, and little cephalization.
A notch between the anterior and dorsal sides that is the oldest part of the shell. Growth occurs in concentric lines around it. The oldest layers are closest to this.
How many layers does the shell of Class Pelecypoda (bivalvia) have?
Three layers. Periostracum layer (outer), prismatic layer (middle), and nacreous (inner) layer.
Where does pearl formation come from in Class Pelecypoda (bivalvia)>
From the mantle.
What are food particles caught by in Class Pelecypoda (bivalvia)?
By mucous on the surface of gills and they are carried to the mouth by cilia on the outside of the gills.
What are unwanted particles removed by in Class Pelecypoda (bivalvia)?
Where are proteins and fats digested in Class Pelecypoda (bivalvia)?
Inside of cells (intracellular).
Where are carbohydrates are digested in Class Pelecypoda (bivalvia)?
Outside of cells (extracellular).
What do Class Pelecypoda have in their stomach?
A crystalline style for dissolving surface layers, rolling the food mass and freeing digestive enzymes.
What kind of circulatory system does Class Pelecypoda (bivalvia) have?
What kind of heart does Class Pelecypoda (bivalvia) possess?
A three-chambered heart (2 auricles and 1 ventricle.
Where does the three-chambered heart of Class Pelecypoda (bivalvia) lie in?
The pericardial cavity.
Open cavities where blood bathes the organs directly.
Pattern of blood flow in Class Pelecypoda (bivalvia).
Where do the two major ateries of Class Pelecypoda (bivalvia) carry blood to?
The mantle and the foot.
Where do some pathways take the blood through in Class Pelecypoda (bivalvia)?
Through a pair of nephidia (kidneys) where liquid wastes are filtered out of the blood and through the gills where gases are exchanged.
How developed are the sense organs in Class Pelecypoda (bivalvia)?
What does the nervous system of Class Pelecypoda (bivalvia) possess?
Three pair of ganglia (Cerebral, Pedal, and Visceral).
What may visceral ganglia of Class Pelecypoda (bivalvia) be sensitive to?
Chemicals in the water.
What are the sensory organs of Class Pelecypoda (bivalvia)?
Have statocysts in the foot, tactile cells, pigment cells, and scallops have blue eyes.
Are sexes of Class Pelecypoda (bivalvia) separate?
Yes (dioecious), only a few are hermaphroditic.
Describe reproduction of Class Pelecypoda (bivalvia) (copulation).
They do not copulate, yet fertilization is usually internal.
1) Sperm shed into water by the male enters the female's....what? (Class Pelecypoda reproduction)
2) Fertilization occurs, and zygotes develop within the gills to become....what? (Class Pelecypoda reproduction)
3) The glochidia are expelled into the water and must find fish to...what? (Class Pelecypoda reproduction)
4) After being attached to fish 3-12 weeks, they drop off and develop into...what? (Class Pelecypoda reproduction)
A young clam.
What do some marine pelecypods shed sperm and eggs into?
Water, and fertilization is external.
The head footed mollusks.
What are examples of Class Cephalopoda?
What class is an important food source for fish and people?
What is the habitat of Class Cephalopoda?
Which class is the most complex of all the mollusks, and one of the most complex invertebrates period?
What is the head/foot divided into in Class Cephalopoda?
Tentacles, which usually have suckers.
What functions do the suckers serve?
Sticking to things, grabbing prey, grabbing food, reproduction ->modified as sperm packets.
Which class has jaws as well as a radula?
Which class exhibits a reduced shell (called a pen in a squid) or no shell at all.
What do most species of Class Cephalopoda have?
An ink gland with an ink sac that secretes sepia for defense.
This class has a well-developed head with large complex eyes. They eyes are as well developed as ours are (they have a cornea, a lens, two fluid filled chambers on both sides of the lens, and a retina).
What holds the eyes in constant relation to gravity so the slit shaped pupils are always in horizontal orientation in Class Cephalopoda?
What does the brain in Class Cephalopoda have?
Several lobes with millions of nerve cells.
How many pair of gills does Class Cephalopoda have?
Class Cephalopoda have radial and circular muslces to..?
Class Cephalopoda can swim by forcefully expelling water from what?
The mantle cavity through a ventral funnel (or siphon), that can be pointed to control direction.
Describe the sexes of Class Cephalopoda.
Separate sexes (dioecious)
What do juveniles hatch from in Class Cephalopoda?
Eggs. There is no free-swimming larval stage, as the juveniles resemble adults.