Lecture 4 Flashcards
in what type of animals do body cavities exist?
-triploblastic animals
what are the 3 grades of body cavities?
-(eu)coelomates
-pseudocoelomates
-acoelomates
what is a (eu)coelomates body cavity?
-full cavity completely lined with mesoderm
-closed circulatory system
what phylums have a (eu)coelomate body cavity?
-annelids
-chordates
-echinoderms
-molluscs
-arthropods
what is a pseudocoelomate body cavity?
-false cavity only partially lined by tissue derived from the mesoderm
what phylum has a pseudocoelomate body cavity?
-nematodes
what is a acoelomate body cavity?
-no body cavity (not completely formed)
-no space between tissue layers
what phylum has a acoelomate body cavity?
-platyhelminthes
what does the lophotrochozoa clade feature?
-animals with a wide range of body forms
-contains bilaterian animals
-have a lophophore
-have a trochophore larva form
what is a lophophore?
-feeding structure in aquatic organisms
what is a trophophore larva form?
-common larval form
-simple
-3 tissue systems
-complete gut (coelomate)
what bilaterian animals are found within the lophotrochozoa clade?
-coelomates (full cavity with a digestive tract and 2 openings)
-ex: annelids, molluscs, brachiopods, rotifers, and flatworms
what are the 4 common structures within the mollusca phylum?
-muscular foot
-mantle
-radula
-visceral mass
what is the purpose of the muscular foot?
-helps with movement, digging, and capturing prey
what is the mantle and what is its purpose?
-water filled chamber containing gills (or lungs), anus, and excretory pores
-produces the shell
what is the purpose of the radula?
-functions as a tongue to capture food
what is the purpose of the visceral mass? why is it pushed in?
-houses internal organs
-pushed in b/c of the large foot
what are the 4 major classes of molluscs?
-gastropods
-bivalvia
-polyplacophora
-cephalopoda
what are the key features of the gastropod class? what are examples?
-1 piece shell
-use radula to feed off plants + algae
-ex: snails + slugs
what are the key features of the bivalvia class? what are examples?
-2 piece shell
-no distinct head
-suspension feeders
-sedentary lives
-ex: clams, oysters, and other bivalves
what are the key features of the polyplacophora class? what are examples?
-many piece shell
-scrape algae from rocks
-ex: chitons
what are key features of the cephalopoda class? what are examples?
-intelligent animals
-can camouflage
-use tentacles to grasp prey
-ex: squids, octopuses, and cuttlefish
what are the key aspects of the annelida phylum?
-segmented worms
-live in water or damp soil
-have compartmentalized organs
-have a true body cavity + complete gut
-have a trochophore larva stage (undergo metamorphosis)
what are the 2 clades within the annelida phylum?
-errantia
-sedentaria
what are the key aspects of the errantia clade?
-active
-mostly marine
-predators or grazers (plant feeders)
-2 appendages
what are the 2 appendages found within the errantia clade?
-parapodia
-palps
what are parapodia used for? how many are present in each organism?
-locomotion (quickness)
-one pair per segment
what are palps used for? what do they resemble?
-sensation
-look like antennae whiskers
what are the key aspects of the sedentaria clade? what are examples?
-less active (sedentary)
-live in marine sediment or soil
-can live in tubes
-ex: leeches, earthworms, tubeworms
why do worms within the sedentaria clade have slower movement?
-no extensions on their segments
if worms live in tubes what will they have?
-elaborate gills
what may leeches be predators of?
-other invertebrates
how do earthworms get their nutrients?
-extracted from the soil
what are key aspects of the brachiopoda phylum?
-attached to the seafloor
-have a lophophore
-no trochophore larval stage
-typically lamp shells
what does it mean for brachiopods to be considered ‘lamp shells’?
-2 muscles (1 for opening, 1 for closing)
-dorsal half and a ventral half
-also have bilateral symmetry
what are the 2 main clades within the brachipods?
-inarticulata
-articulata
what are the key aspects of the inarticulata clade? what is an example of an organism?
-small or no hinge (not as lamp shell like)
-complete gut (mouth, intestinal tract, and anus)
-ex: lingula
what are the key aspects of the articulata clade?
-large hinge (strong/robust)
-incomplete gut (no exit for waste, enters + exits through mouth)
-intestine protrudes out the back of the shell
what are the key aspects of the platyhelminthes phylum?
-flatworms
-rudimentary cephalization (undeveloped)
-live in marine/freshwater or terrestrial habitats
-gas exchange through the skin
-can be free living or parasitic
where is there evolutionary loss in platyhelminthes?
-incomplete gut (acoelomate)
-only a gastrovascular cavity
what does a platyhelminthes flat body help them with? what does it limit?
-disguising
-limits room for compartmentalization
what does it mean to be parasitic?
-another organism is needed to carry out its lifestyle
what is the clade within the platyhelminthes?
-neodermata
what are the 2 classes within the neodermata clade?
-parasitic trematodes (flukes)
-cestodes
what are the key features of the parasitic trematodes? what is an example?
-parasitic
-ex: schistosoma parasitic worm (swimmers itch)
what are the key features of the cestodes?
-have loss of a gastrovascular cavity over evolution
-can reach 20m in length
-ex: tapeworms (live inside an organism’s intestines)
what is an exoskeleton? what is its purpose?
-tough cuticle or shell
-protects the organism from environmental conditions
what is typically involved when an organism has a exoskelton?
-moulting/periodic shedding followed by rapid growth
what is stepwise growth? when does it take place?
-when the exoskeleton sheds, organism grows rapidly, and a new exoskeleton forms (repeats)
-when the organism cannot grow continuously and is limited by the size of its exoskeleton
when does the process of stepwise growth stop?
-once an organism has reached its full size
where did stepwise growth/evolution of an exoskeleton begin?
-ecdysozoa clade
-nematoda + arthropods
what are the key aspects of the nematoda phylum?
-most common animal on earth
-small or microscopic
-free living or parasitic lifestyles
-pseudocoelomate
-body is covered with a cuticle
-flexible bodies
what type of hosts can a nemotode have?
-plant or animal hosts
what is an example of a nematode?
-roundworms
