Lecture 22 & 23 Lophotrochozoa Flashcards
which clade do most animals belong to?
- bilatera
- have triploblastic symmetry
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
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
what does the clade bilatera include?
lophotrochozoa, ecdysozoa, deuterstomia
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
what are two classes in platyhelminthes?
- class turbellaria
- class cestodia
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
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
what are proglottids?
- in class cestodia – tapeworms — devoted to reproduction, mature proglottids are filled with eggs
what are proglottids?
- in class cestodia – tapeworms — devoted to reproduction, mature proglottids are filled with eggs
what is the life cycle of cestodia?
complex
- need an intermediate host and a definite host
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
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
what is phylum brachiopoda?
lophophorate
- lamp shells
- superficially resemble bivalve mulluscs
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
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
