what are the two major groups of bilaterally symmetric, triploblastic, coelomate animals?
protostomes and deuterostomes
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what are the two monophyletic groups of protostomes?
Lophotrochozoa and Ecdysozoa
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Lophotrochozoan
- inspired by the presence of a feedig structure called a lophophore and type of larva called a trochophore
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lophophore
specialized structure that rings the mouth of these animals and functions in suspension feeding
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Trochophore
type of larva common in several phyla of lophotrochozoa
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what is the primary contrast between lophotrochozoans and ecdysozoans?
The methods of growth
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How do ecdysozoans grow?
by molting
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molting
shedding of the soft cuticle or hard exoskeleton.
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what do the cuticle and exoskeleton serve as from predators in ecdysozoans?
protection
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what are the most prominent phyla in ecdysozoans?
roundworms (nematoda) and arthropods (arthropoda)
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T/F all protostomes are triploblastic bilaterians and undergo similar embryonic development
True
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ectoderm
outertube
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endoderm
inner tube
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mesoderm
between the two tubes
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coelom
- functions as a hydrostatic skeleton that is the basis of movement.
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tagmata
Prominent body regions in arthropods, such as the head, thorax, and abdomen
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How are arthropods distinguished?
by their jointed limbs and chitinous exoskeleton
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hemocoel
spacious body cavity that provides space for internal organs and circulation of fluids in arthropds
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Three major components of the molluscan body plan
foot, visceral mass, mantle
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foot
a large muscle located at the base of the animal and usually used in movement
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visceral mass
contains most of the internal organs
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mantle
tissue layer that covers the visceral mass and forms the mantle cavity
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Echiurans
a type of annelid that deposits feed using proboscis
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proboscis
an extended structure in echiurans that forms a gutter leading to the mouth
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priapulids
have a toothed throat that can be turned inside out to grab prey and then retracted
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nemerteans
have a barb-tipped proboscis that extends and spears/ entangles the prey and then retracts
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what are the new adaptations required for protostomes to make the transition to land?
they need to be able to
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what increases the efficiency of gas exchange accross the body surface of roundworms and earthworms?
high surface-area-to-volume ratio
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how do arthropods and many mollusks minimize water loss when moving onto land?
they have gills and other respiratory structures located inside the body
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adaptations for feeding
suspension, deposit, liquid and mass feeders.
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Adaptations for moving
depends on variation and presence or absence of limbs and the
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jointed limbs
in arthropods enable rapid, precise running, walking and jumping
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insect wing
one of the most important adaptations in the history of life
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mollusk foot
allows individuals to crawl along a surface
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jet propulsion
in cephalopods propels the animals forward when the mantle mascles force water from the siphon
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parthenogenesis
how many crustacean and insect species reproduce asexually, in which unfertilized eggs develop into offspring
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two unique reproductive innovations that occurred during protosome diversification
the evolution of metamorphosis, an egg that would not dry on land
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Main phylums of lophotrochozoans
rotifera, platyhelminthes, annelida, mollusca,
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rotifera
- live on damp soilds and marine/ freshwater environments
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Platyhelminthes
-flatworms
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turbellarians
free-living flatworms (platyhelminthes)
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- hunters/ scavangers
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-reproduce asexually by splitting themselves in half and sexually by fertilization
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cestodes
(platyhelminthes) endoparasitic tapeworms
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- parasitic
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- flukes and tapeworms
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trematodes
(platyhelminthes) endo- or ectoparasitic flukes.
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- gulp host tissues through mouth
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- flukes mainly
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Annelida
segmented worms
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- segmented body plan
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-chaetae
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-parapodia
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- separated into polychaetae and clitellata
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The common ancestor of the annelids had a key synapomorphy in addition to segmentation: numerous, bristlelike extensions called _______ that extend from appendages called _______
chaetae, parapodia
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Polychaetes
include those lineages that retained many chaetae and are mostly marine
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Clitellata
have lost or reduced chaetae, have two monophyletic groups: oligochaeta (oligochaetes) and hirudinea (leeches)
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What are the characteristics of clitellata
live in freshwater and marine environments and compared to other annelids have a smaller coelom which consists of connected chambers
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oligochaetae
(clitellata) they lack parapodia nad have fewer chaetae than do polychaetes.
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They are deposit feeders in the soil.
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Hirundea
(clitellata)
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- are blood-sucking parasites
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- most live in freshwater
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-secretes an anaesthetic and hirudin
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Mollusca
- most species rich and morphologically diverse
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- marine
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- have 4 lineages: bivalves, gastropods, chitons, cephalopods
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what are the four most important lineages of mollusca?
Bivalves, gastropods, chitons, cephalopods
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Bivalvia
(mollusca)
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- suspension eaters
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-include clams, oysters, scallops, and mussels
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- two separate shells for protection
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- most live in ocean
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- reproduce sexually and have two larval stages: the trochophore adn the veliger