Topic 22: Lophotrochozoa Flashcards
what clade do most animals with bilateral symmertry belong to?
clade bilateria
are bilateral animals tripoblastic or dipoblastic
tripoblastic, because they have a mesoderm layer
what embryotic layer leads to the formation of mucsles and internal organs
the mesoderm
what are the two major groups in clade bilateria
prostosomes and deuterostomes
what do most bilaterians possess
coelom (body cavity) and a digestive tract with a mouth and an anus
how are bilaterians strongly differentiated?
they are differentiaed along their anterior-prosterior axis
what does this differentiation along the anterior posteriro axis facilitate in?
directional motility
term to describe the anterior region as a head regionand or the concentration of neuro ganglia (the brain)
cephalization
what does cephalization involve the concentration of?
involves the concentration of nueral ganglia, which form the brain
do sessile bilaterians have increased or reduced cephalization?
reduced bestie
what is basal to bilaterians
phylum acoela
what is acoela
marine worms
characteristics of acoela
- small flattened body with minimal cephalization and no brain
- no body cavity (coelem or hemocoel) and complex organ systems
- simple digestive system with a mouth but no anus
what is the type of digestion that acoela undergo
endocellular digestion
how is clade lophotropchoza defined? and why?
defined by molecukar phylogeny since they have no unifying characteristic
clade with the widest range of different body plans
lophotropchoza
what are the characteristics of fphylum platyhelminthes
- simple body plan
- lack of fluid filled cavities
- incomplete digestive tract
- no anus
- no circulatory or gas exchange systems
two lineages of flatworms
cetenulida (chain worms) and Phabditophora ( parasitic flatworms)
free-living rhabditophora (parasitic flatworms) that inhabit freshwater
planarians
characteristics of planerians
- anteriror cephalization,
- paired ganglia (dense cluster of nerve cells) that extend to a pair of ventral nerve chords (from a cephalized nerve net)
- no anus
- hermaphodites (asexually or sexually)
- ## -gastrovascular cavity with one opening
where do parasitic rhabditophorans live?
inside or on other animals
characteristics of parasitic rhibditophora
- live in or on other animals
- use suckers and hooks to attatch to prey
- have a complex life cycle
difference between intermediate host and definitive host
intermediate: asexual reproduction occurs
definitive: parasite undergoes sexual reproduction
two important groups in parasitic rhabditophora
tapeworms and trematodes
characteristics of trematodes
- parasite
- complex life cycle with alternating sexual and asexual stages
characteristics of tapeworms
- parasites of vertebrae
- lack a digestive system and depend on the host’s digestive system
- scolex has suckers and hooks
- scholex is a long chain of segments (proglottids) with hermaphodite sex organs
- complex life cycle
a unique feeding structure lophophorates that is a fan of ciliated tentacles sourrounding the mouth
lophophore
do lophophorates have a coelom?
yes
two phyla of lophophorates
ectoprocta and brachiopoda, both are aquatic
shared characteristics of locophorates (ectoprocta and brachiopoda)
sessile and motile, have planktonic larval stages after sexual reproduction
sessile colonial animals that resemble coral, mostly encased in a hard exoskeleton, capable of sexual and asexual reproduction, and are suspension feeders using a retractable lophophore
ectoprots
what are ectoprots
sessile colonial animals that resemble coral, mostly encased in a hard exoskeleton, capable of sexual and asexual reproduction, and are suspension feeders using a retractable lophophore
phylum that resembles bivalve molluscs, suspension feeders using paired lophophores and have a complete gut and anal orpening
brachiopods
what characterizes phylum mollusca?
soft bodied animals protected by a hard calcareous shell (this shell is reduced in most taxa)
examples: snails, slugs, octopus, squids oysters, clams
primary parts that is a shared common body plan that all molluscs share
- muscular ventral foot (locomotion)
- visceral mass above the foot containing organs
- mantle (thin tissue layer that secretes the shell) with a reduced coelom
descirbe the body plan of a mollusc
unsegemented body and has gills in the mantle cavity for gas exchange and sometimes feeding
how do molluscs feed?
with a radula
do molluscs have a closed or open circulatory system
open circulatory system
phylum with a cilliated trochophore larval stage
molluscs
four major classes of molluscs
-polyplacophora (chitons),
-gastropoda (snail and slugs),
-bivalvia (clams oyster and other bivalves) and
- cephalopoda (quids octopus and chamberes nautiluses)
class that are oval chaled marine animals with a protective shell consisting of eight dorsal plates and use their feet as suctions cups to adhere to surfaces
chiton
class that is aquatic and terrestiral, terestiral species lack gills and have a single coiled tubular shell secreted by the mantle
class gastropoda
how do glastropoda sepcies move?
use muscular motions of the ventral foor or by cilia action
do gastropoda have strong or weak cephalization, and what does this mean?
they have strong cephalization
this means that they have a well developed head, mouth, nueral ganglia (brain, antannae and eyes
class that is aquatic and a shell that devides into two halves that are drawn together bt adductor muscles. some are motile and some are sessile
class bivalvia
what kind of feeders or bivalvia
suspension feeders
they use gills in the mantle cavity for feeding and gas exchange
do bivalvia lack or have cephalization?
lack
class that does not have an external shell and have long tentacles arranged in the mouth. they have complex cephalization and hatch as direct-developing juveniles (minimal adults at birth)
class cephalopoda (octopuses squids, etc.)
cephalopoda have a fused tube of the mantle that fired a jet of water for locomotion
siphon
class that are the only molluscs with a closed circulatory system
cephalopoda
characteristics about class cephalopoda
only class that does not have an external shell and have long tentacles arranged in the mouth. they have complex cephalization and hatch as direct-developing juveniles (minimal adults at birth)
name of the phylum containing segmented worms
phylum annelida
two major clades of phylum annelida
errantiansand sedentarians
characteristics of annelida
- segmented body separated by partitions called septa,
- fluid filled coelom that functions as a hydrostatic skeleton
- have cephalization
- closed circulatory system
- segmented body separated by partitions called septa,
- fluid filled coelom that functions as a hydrostatic skeleton
- have cephalization
- closed circulatory system
clade annelida
what are some characteristics of errantians?
- have parapodia (paddle or ridge like structures on each body segment
- differentiated head with sensory antennae and eyes
- reproduce sexually by free-spawning
- mobile predatory marine organisms
- have parapodia (paddle or ridge like structures on each body segment
- differentiated head with sensory antennae and eyes
- reproduce sexually by free-spawning
clade errantians (centipede)
what are some characteristics of sedetarians (leeches and earthworms)
- less motile
- lack parapodia
- reduced cephalization
- undergo direct development without a trochophore larval stage
- less motile
- lack parapodia
- reduced cephalization
- undergo direct development without a trochophore larval stage
clade sedetarians
what are some characteristics of leeches
- lack parapodia and chaetae
- simultaneous hermaphodites
- reproduce via reciprocol fererilazation
- direct development
- parasites
how do earthworms feed
- ingest soil and dead organic matter
what do earthworms lack? what do they possess?
they lack parapodia and four pair of chaetae per body segemtn
how do earthworms and leeches reproduce
reproduce via recipricol fertilization and undergo direct development, but earthworms do not free-spawn
