Lophotrochozoa- Phylum Mollusca

how many species does this phylum have

90,000 existing species; 70,000 extinct species (550 mya)

what are the characteristics of phylum Mollusca

spiral cleavage; trochophore larva; coelomate; protostomes

what are the four body plans that make up a mollusc

head-foot, visceral mass, mantle, radula

head-foot region purpose

feeding, sensory and locomotor organs

visceral mass

digestive, circulatory, respiratory, and reproductive organs

mantle

secretes a shell (valve) over the visceral mass

mantle cavity

space between mantle and body wall

Radula

protruding, rasping, tounge-like organ

what is the shell secreted by

the mantle

periostracum

outer organic layer composed of conchiolin; protective

middle prismatic layer

biggest layer made of calcium carbonate

inner nacreous layer

next to the mantle; used to capture unwanted items that may harm clam

nervous system of a mollusc

pairs of ganglia with connecting nerve cords

veglier

intermediate larval stage; has the beginning of a foot, mantle and shell ( changes shape; whole trochophore changes size)

What are the five classes of Mollusca

Caudofoveata, Solenogastor, Polyplacophora, Monoplacophora, Schapoda, Gastropoda

Class Caudofoveata and Solenogastres

marine worm-like, shell-less; reduced head, radula and other molluscan anatomy; calcareous spicules give it a shiny look

Kulindroplax (genus)

first mollusc with worm-like body and valves; suggests aplacophora may have evolved rom a shelled ancestor and are monophyletic

Class Polyplacophora

flattened body with eight dorsal calcareous plates; marine, intertidal zone or deep water ( chitons)

Biomineralization

teeth of the radula are composed of magnetic crystalline magnetite

Conchifera clade

univalve shell with periostracum, prismatic, and nacreous layers

Class Monoplacophora

(one-plate) previously considered extinct; rediscovered in 1952; single rounded shell; serially repeated organs: gills, metanephridia, gonads

Class Schaphoda

(tusk shells) Benthic; marine/off-shore; burrow head down in substrate; tube shaped mantle; no gills

Class Gastropods

most diverse molluscan class; univalve shell; coiled or uncoiled; body undergoes torsion or coiling

How many species does class Gastropoda have

Over 70,000 living and 15,000 fossil species

torsion

twisting of body into new form

Coiling

curl of the shell and the visceral mass contained within the shell.

sinistral

left hand coil

Dextral

right hand coiled

What are the Molluscs feeding habits

herbivorous, scavengers, and a few carnivores

what are consequences of torsion

organs in visceral mass switch; loss of organs on one side (bilateral asymmetry); posterior anus and mantle cavity sit on top of the head

Fouling

Waste is washed back over the gills or mouth

What are the three subclasses of Class Gastropoda

prosobranchia, Opisthobranchia, Pulmonta.

Prosobranchia

subphylum that has a operculum(door); heart is location in front of the gill

Opisthobranchia

subphylum where organisms heart located behind the gill

Pulmonta

subphylum that has lost their and breath by a lung; contain penises at the top of had that attach to each other when transferring gametes.

in mollusca, the coelom is most easily seen around what structure

the heart

which process or action resulted in the loss of the right gill in most modern gastrpods

torsion

what is the correct order (outside to inside) of their three shell layers

periostracum, prismatic, nacreous

The pulmonata are a subphylum group of gastropods that...

have lungs instead of gills in most members

Class Bivalvia

laterally compresses, with left and right valves, dorsal hinge

how does Class Bivalvia eat

sedentary suspension feeders; use ciliary currents tin gills to collect food

how does class Bivalvia reproduce

Dioecious; external fertilization in marine bivalves; internal fertilization in freshwater bivalves

what are the larval stages in Class Bivalvia

trochophore, velgier, and spat stages

Glochidia

velgier larvae stage of freshwater clams

Class Cephalopoda

Active Marine Predators; strong-beak like jaws to grasp prey

What is the system class cephalopods have

closed circulatory system with three hearts

umbo

closest to anterior and dorsal side

what feature is the most complex in Cephalopods

the eyes

syphon

tube on the posterior side of cephalopods