lecture 14 Flashcards
what is lophotrochozoa
smaller clade of spiralia
what larva do most lophotrochozoa taxa have?
lophophore or trochohore larva
what is mollusca a member of
lophotrochozoa
what larva is present in many mollusca
trochophore larva
what is trochophore larva
what type of organs
a type of primary larva with apical organ
what is the second most species rich invertebrate [hylum
mulluscah
ow many described species of mollusca
73,000
what is cool about size rannge of mollusca
they have the greatest size range of any phylum of invertebrates
general features of mollusca coelom
small eucoelom and large open haemocoelic circulatory system
haemolymph
circulatory fluid, bathes some organs dirrectly
do mollusca have heart?
they have chambered heart
how does the euceolum arise in mollusca
via schizocoely but is greatly reduced
what are the functions of the haemocoel
it is extensive, it functions as circulatory system and a hydrostatic skeleton
what are 8 common features in mollusca
- small eucoelom and large open haemocoelic circ system
- chambered heart
- have mantle
- calcareous shell or and small sclerites
- foot
- radula
- gut w large digestive glands
- gills called ctenidia
- excretory system including metanephridia
metanephridia
typical in large animals
filtration occurs in the structure separate frp, resorption and transport
what are two clades of mollusca
aculifera and conchifera
clade aculifera
-not covered by large shells
-incorporate calcareaous sclerites into mantle.
clade conchifera
most of body covered by one or two large shells
what is the clade some aculifera are in?
aplacophora
what molluscs groups have solid calcareous shell plates
every group except aplacophorans
what produces shell
shell glands in mantle
the three layers of the shell
periostracum layer
prismatic layer
nacreous layer
periostractum
tough proteinacrous layer
prismatic layer
chalky calcareous layer, thickest layer of shell
nacreous layer
shiny and smooth inner layer
the mother of pearl
how do pearls form
when irritant gets into mantle
ctenidia
multi leaved gills
what is the function of ctenidia
gas exchange
what type of gas exchange happens in ctendium
counter current exchange
morphology of ctenidium
long flattened central axis with two haemolymph vessels. along with alternately arranged ciliated lamellae
sense organs of molluscs
eyes
statocyst
tentacles
function of eyes
range from ligth detectors to image forming
statocyst function
gravity detecting organ
tentacles function molluscs
touch and chemoreception, may bear eyes in gastropoda
sexes in mollusca
mostly seperate sex, hermaphroditism is common
fertilization in molluscs
mostly external
development in molluscs
mostly indirect with trochophore larva
