Lecture 22 & 23 Lophotrochozoa Flashcards by obsolete e

which clade do most animals belong to?

bilatera

- have triploblastic symmetry

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what is phylum acoela?

basal bilaterans
mostly marine worms
aceolomates – no body cavities
flat, minimal cephalization, no brain
no anus, no gut cavity – endocellular digestion instead, use endocytosis to strip off food

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what are lophotrochozoa?

what does it include (6)

identified by molecular data
widest range of animal body forms
some develop lophophores for feeding
others pass through trochophore larval stage, some have neither
includes: platyhelminthes, rotifers, ectoprocts, brachiopoda, mollusca, annelids

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what does the clade bilatera include?

lophotrochozoa, ecdysozoa, deuterstomia

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what is phylum platyhelminthes?

flatworms
triploblastic
acoelomate
do not have a complete digestive system – have a mouth and a gut lumen but no anus
no special circulatory or gas exchange system

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what are two classes in platyhelminthes?

class turbellaria

- class cestodia

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what is class turbellaria?

platyhelminthes
free living flatworms
mostly predatory
epidermis covered by cilia
have ventral nerve cords
a pair of ganglia
gastrovascular cavity with no anal opening

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what is class cestodia?

platyhelminthes
tapeworms
entirely parasitic
lack digestive system
scolex – front of body modified for holding onto host’s gut – suckers and hooks
proglottids – long chain of segments devoted to reprodution

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what are proglottids?

in class cestodia – tapeworms — devoted to reproduction, mature proglottids are filled with eggs

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what are proglottids?

in class cestodia – tapeworms — devoted to reproduction, mature proglottids are filled with eggs

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what is the life cycle of cestodia?

complex

- need an intermediate host and a definite host

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what is phylum rotifera?

tiny animals that inhabit fresh water, ocean, damp soil
truly multicellular and have specialized organ systems
have an alimentary canal – a digestive tube with separate mouth and anus
fluid-filled pseudocoelom
reproduce using parthogenesis: females produce offspring via unfertilized eggs

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what are the two lophophorates in lophotrochozoa?

what are characteristics of lophophorates?

ectoprocts
brachiopods
have lophophores, which is a crown of tentacles around their mouth
true coelom

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what is phylum brachiopoda?

lophophorate

lamp shells
superficially resemble bivalve mulluscs

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what is phylum brachiopoda?

lophophorate

lamp shells
superficially resemble bivalve mulluscs
attach to sea floor by a stalk
complete gut with anal opening
suspension feed using paired lophophores

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what is phylum ectoprocta?

lophophorate

also known as bryozoans
sessile colonial animals, superficially resemble coral
hard exoskeleton
filter feed using retractable lophophores

what are the trochozoans in lophotrochozoans? (2)

what are they characterized by?

annelida, mollusca
shared patterns of early embryonic development
microscopic swimming trochophore larvae
larvae have 2 bands of cilia around the middle for swimming and food gathering

what is phylum mollusca?

trochozoan

snails, slugs, oysters, clams, octupi, squids
soft bodied animals, sometimes have a hard shell which is calcerous (CaCO3)

what are characteristics of mollusca?

have a similar body plan
mantle: thin layer of tissue that secretes the shell
mantle cavity: water filled, respiratory chamber???
muscular ventral foot for movement
organs contained in a visceral mass above food
mouthparts in a strap-like rasping organ called a radula
gills for gas exchange
open circ system (except for octupi, and squids)
reduced coelom
not clearly segmented

what are the four major classes of mollusca?

polyplacophora – chitons
gastropoda – snails and slugs
bivalva – clams, oysters, other bivalves
cephalopoda – squids, octupi, cuttlefish, chambered nautiluses

what are the four major classes of mollusca?

polyplacophora – chitons
gastropoda – snails and slugs
bivalva – clams, oysters, other bivalves
cephalopoda – squids, octupi, cuttlefish, chambered nautiluses

what are polyplacophora?

trochophores - molluscs - chitons

ovale shaped marine animals encased in armour of 8 dorsal plate
use foot like a suction cup to grip rock, and their radula to scrape off rock surfaces

what are gastropoda?

trochophores - molluscs - snails and relatives

glide using contractions of a muscular foot
torsion: gastropod synapomorphy: visceral mass and mantle twists during larval development
most are marine (have larvae), many freshwater and terrestrial (direct development)
terrestrial have lost their gills and adapted mantle cavity into a lung
NUDIBRACHS: shell less marine gastropods, some are protected by nematocysts of cnidarians – eat cnidarians and store nematocysts in their own tissues

what is class bivalva?

trochophores - molluscs - clams, oysters, mussels, scallops

have a shell divided into two halves drawn together by adductor muscles
filter feeders: mantle cavity contains gills used for feeding and gas exchange, NO RADULA (dont really have a head)
some are sessile, most sedentary

very important economically

what is class bivalva?

trochophores - molluscs - clams, oysters, mussels, scallops - have a shell divided into two halves drawn together by adductor muscles - filter feeders: mantle cavity contains gills used for feeding and gas exchange, NO RADULA (dont really have a head) - some are sessile, most sedentary very important economically

what is class cephalopoda?

trochophores - molluscs - squids, octopi, cuttlefish - no external shell (exception of nautilus) - some may have internal shell (cuttlebone of cuttlefish) - long tentacles around the mouth -- modified from molluscan foot - PREDATORY -- radula is modified into a biting beak - siphon is a fused tube of mantle used for jet-propulsion - only molluscs with CLOSED CIRCULATORY SYSTEM - complex behaviour - do not have trochophore larvae -- DIRECT DEVELOPING JUVENIILES

what are annelida?

trochophores - segmented worms - three classes: polychaeta, oligochaeta (earthworms and relatives), hirundinea (leeches) - segmented, separated by internal septa - ceolomates - closed circulatory system - complete digestive system with an anus

what is class polychaeta?

trochophores - annelida - almost entirely marine - parapodia: body segments with fleshy lobes which bear chaetae (chitinous bristles)

what is class polychaeta?

trochophores - annelida - almost entirely marine - parapodia: body segments with fleshy lobes which bear chaetae (chitinous bristles) - clearly differentiated head with sensory antennae - sedentary, or errant - errant are usually predatory - sedentary: ingest substrate, suspension feed (filter food particles out of the water column), deposit feed (trail sticky tentacles over substrate and lick off adhering matter) - free-spawning

what are oligochaetes?

trochophores - annelida - less diverse than polychaetes - lack parapodia and a well developed head - most feed by ingesting substrate and digesting organic matter - most are SIMULTANEOUS HERMAPHRODITES but cross fertilize by copulation -- produces gelatinous cocoon with secretions from clitellum, deposits eggs in cocoon, slides cocoon forwards to seminal receptacle -- still EXTERNAL FERTILIZATION - DIRECT DEVELOPMENT - some asexual reproduction

what are class hirundinea?

trochophores - annelida -- LEECHES - lack parapodia, have clitellum, lack chaetae - predators