lecture 16- bivalve Flashcards
what clade is bivalve
conchifera
what is class bivalve
mussels and oysters and clams and shit
how many spp bivalve
10000
habitat of bivalves
most marine some freshwater
What are bivalves modified for?
burrowing and feeding on fine particles
what is a bivalve shell
two valves hinged dorsally and kept aligned with hinge teeth.
What keeps valves closed
adductor muscles
what are some adaptations of bivalves
bivalve shell
loss of radula
byssus
lateral compression of body
adductor muscles
ligament w hinge of shell
bivalve features
Head
Ctenidia
Foot
Mantle
-head very reduced and lacks radula
-ctenidia modified for filter feeding
-produce byssal threads
-foot modified for burrowing
-mantle ofter modified into siphons
what is weird about scallop mantle
they have eyes in their mantle
juvenile shell
umbo
where is the hinge ligament in respect to umbo
posterior
what happens to the ligament when the adductor muscles contract
the valve closes and the outer part of ligament is stretched and inner part is compressed
what is contained in the hinge area
teeth
what do the teeth do
keep shell from slipping
how many ctenidia do bivalves have
one pair
different types of ctenidia
respiratory ctenidia and filter feeding ctenidia
what are respiratory ctenidia called
protobranch gills
what are filter feeding ctenidia called
lamellibranch gills
lamellibranch gills morphology
filaments arranged in Vs of ascending and descending arms called demibranches
what is the mantle cavity divided into in lamellibranch gills
an exhalent and inhalent chamber
what are the two types of lamellibranch gills
filibranch and eulamellibranch
filibranch gills
adjacent gill filaments attached by tufts of cilia
eulamellibranch gills
adjacent gill filaments attached by bridges of solid tissue
which clades have protobranch gills and lamellibranch gills
-the basal clade protobranchia have protobranch gills
-all the other clades have lamellibranch gills.
How do protobranch bivalves feed
use two pairs of large labial palps
where are low density particles sent in protobranch
towards the mouth as they are likely organic
where are high density particles sent in protobranch
ejected into mantle cavity
how do lamellibranch bivalves feed
gills filter particles
how do the gills in lamellibranch bivalves filter?
-frontolateral cilia flick particles to surface of filament.
-particles are then moved towards food groove
-then moved to palps where they are sorted
how are particles ejected in eumellibranchs
they accumulate and are ejected as pseudofeces
how do bivalves burrow
shell and foot act as alternating anchors
how do byssal threads work
harden as is comes into contact w sea water
how do byssal threads work in muscles
they are produced throughout life
how do oysters attach themselves to substrate
they cement themselves
bivalve sexes
seperate
what is spawning like in marine bivalves
most gametes are spawned freely into water
what is spawnign liek in freshwater bivalves
sperm inhaled by female and fertilization is in mantle caviry, they are brooded
larval stages of most bivalves
free swimming trochophore to later veliger
glochidia
larva that absorb nutrients and ride fish
fish are baited because mantle looks like fish
