Week 5 Flashcards
molting ecdysis
flexible yet tough cuticle requires molting in order to grow, but also provides protection while being thinner and lighter than mineral skeleton
how times does annelids molt before maturing
4 times
what does molting often include in nematoda
metamorphosis
what does metamorphosis allow for nematoda to have
separate body plans in juveniles and adults
are nematoda tripoblastic bilateria
yes
what is pseudocoel a remnant of
blastocoel
pseudocoelmates
a body cavity (psedocoel or coelom)
space for development of organ systems
simple means of circulating materials around the body
a hydrostatic skelton
hydrostatic skeleton
fluid filled cavity is a more rigid structure for muscles to act against than the tissue filled body of an acoelomate
do most pseudocoelmates have a complete digestive tract
yes
Phylum Nematoda characteristics
roundworms 25,000 species marine, freshwater, wet soils, inside plants, and animals unsegmented, pseudocoelmate, protosome, tribloblastic, bilaterians vermirorm body posses a complete gut cuticle that molts ubiquitous and abundant
vermifrom
worm like
do nematodes have a complete, one-way digestive tract
yes
what percentage of Phylum Nematoda is parastic
50%
is Phylum Nematoda an important group of parasites
yes
Phylum Nematoda form & functions
collagenous cuticles, secreted by hypodermis
4 juvenile stages, serparated by molts
mesoderm develops into muscle bundles around outside wall of body (longitudinal only, no circular)
degestive tract
dorsal and ventral nerve cords
nerve cords connected to circular ganglion (simple brain) around pharynx
digestive tract of Phylum Nematode
mouth > pharynx > intestine > rectum > anus
where does mesoderm develop into muscles bundles
around outside wall of body
how do muscles work in Phylum Nematoda
muscles sends out processes to dorsal and ventral nerves cords
how are muscles connected in Phylum Nematoda
connected not by nerves but by evaginations of muscles themselves
where do nerve cord connect in Phylum Nematoda
to circular ganglion (simple brain) around pharynx
Phylum Nematoda response to stimuli
fluid in pseudocoelom under high pressure
inelastic cuticle
these form a hydrostatic skeleton
only longitudinal muscles
contract muscles on one half of body then the other
can only bend in dorsal or ventral direction
what causes roundness in Phylum Nematoda
high pressure, cuticle contains pressure, can use pressure as a hydrostatic skeleton
can Phylum Nematoda move without a substrate
no
Phylum Nematoda energy transformation
pharynx opens into complete digestive tract, unidirectional processing of food
first animal we’ve really looked at that has a true one way digestive system
pharynx needed to pump food into digestive system because of that high internal pressure
anus opens using dilator muscles, pressure pushes contents out
may have “teeth” or stylet to puncture cells, depending on diet
Phylum Nematoda reproduction
sexes vary depending on species most are dioceious some species have 3 or more sexes copulatory spicules in males ameboid sperm
ameboid sperm
move via pseudopods instead of flagellum
are spicules a true intromittent organ
no they do not conduct sperm
nematode who’s who in human diseases
ascaris pinworms hookworms trichina worms filarial worms guinea worms
Ascaris lumbricoides
giant round worms
how many people are infect with Ascaris lumbricoides
807 to 1.2 billon people
how many eggs can a single female Ascaris lumbricoides reproduce in a day
200,000 eggs
how is Ascaris lumbricoides contracted
eating raw veggies contaminated with shelled juveniles often passes infection,
Enterobius vermicules
pinworms “seatworms”
relatively small, females with pointed posterior end, males curled
what is the most common nematode parasite in North America
Enterobious vermicularis
20% of children
10% of adults
what does “seatworm” refer to
main symptom of pinworm infection
itchy butt
how does Enterobius vermicules develop
males develop from unfertilized eggs,
females develop from fertilized eggs
Trichina worm
Trichinella spp
can infect humans through cysts in undercooked pork
one of largest known intracellular parasties
transforms host muscle cells into nurse cells
what causes trichinosis
encysted Trichinella
juveniles change host cell gene expression, become nurse cells that nourish worm
what can Trichina worms infect
wide variety of mammals
humans, pigs, rats, cats, dogs,
what can a heavy infection of Trichina worms cause
possible neurological symptoms, heart disease, and death
filarial worms
live in lymph passages and block flow of lymph
elephantiasis
elephantiasis
excessive growth of connective tissue, swelling
how many species of flarial worms infect humans
8
filarial worm: Dirofilaria immitis
carried by mosquitos
found in mammals(canids, felids, humans)
what is the prevalence of Dirofilaria immitis in dogs
may be as high as 20%
what is the most common filarial worm in the US
Dirofilaria immitis
guinea worms: Dracunculus medinensis
up to 1 meter long, 2 mm in diameter
unusual live cycle
juveniles escape host via open blister, exposing the adult female as well
how do you contract guinea worm: Dracunculus medinensis
by drinking stagnant water with copepods infected with larvae
copepods
tiny crustaceans
what does the blister of Dracunculus medinensis cause
intense burning sensation, called “fiery serpent”
how so you remove Dracunculus medinensis
soaking in water to coax out worm and slowly pulling out
stop if resistance is met to avoid breaking worm
make take several days to fully extract
often kept wrapped around a stick to maintain tension
what are nematodes important for
ecosystem function
especially carbon and nitrogen cycle
metamerism
serial repetition of similar body segments, along longitudinal axis (metamere or somites)
seen in protostomes and deuterostomes
annelids, arthoprods, chordaes, segment- specific genes involved
how are different body parts of an animal produced
activation of different combinations of genes in different segments
do all cells within an organism have the same DNA
yes
spicuncula
peanut worms, have lost segmentation, live in burrows
Phylum Annelida characteristics
segmented
vermiform
protostome bilateral coelomates
use a hydraulic skeleton and setae (chaetae) for locomotion
most possess a complete digestive tract, filtration nephridia, and a closed circulatory system
setae
bristles that help anchor things like earthworms in the soil and can help marine forms swim
lost in some groups
what do annelids have on nematodes
true coelomic cavity
complex circulatory system with muscular vessels and aortic arches
specialization of head region
metamerism
serial repetition of body parts
coelomic cavity of annelids
expanded, divided by septa, allows for more control of body and hydrostatic skeleton
circulatory system in annelids
closed circulatory system main dorsal and ventral vessels aortic arches each segment has vessels that branch from ventral vessels into organs and muscles blood collects back into dorsal vessels
aortic arches
function like heart, pump blood
Phylum Annelids body form
well developed coelom, fluid functions as hydrostatic skeleton, helps with nutrient and oxygen transport
peritoneum lines segment, including septa
have chitinous setae, some with parapodia
peritoneum
layer of mesodermal epithelium
parapodia
paddle like appendages
chitinous setae on parapodia
what divides segments
septa
coelom of annelids
coelomic fluid helps with nutrient and oxygen transport, and also functions as a hydrostatic skeleton
what does each segment of an annelid have
2 coelomic compartments, separated by mesentaries (dorsal and ventral) which support internal structures
Phylum Annelid sementation
segmentation into metameres
repeated nervous system structures for coordination
excretory system in Phylum Annelid
each segment contains a pair of nephridia
portion of the tubule that pierces the septum has a ciliated funnel on it
cilia beat and move fluid through into the next segment, then out of the excretory opening
niphridia selectivley uptake salts, glucose, and water
nephridiopore
excretory opening
what is so great about segmentation/metamerism
development of much greater complexity in structure and function possible
increased efficiency burrowing
independent and separate movements by different segments
fine control of movements= more sophisticated nervous system
built in redundancy- if one segment fails, others can still function
Annelid diversity
22,000 species
marine, freshwater, moist terrestrail
traditionally divided into three group: polychaetes, oligochaetes, leeches
polychaetes
mostly marine, make up most of the annelids, errant and sedentary forms
sedentaria
includes the earthworms and leeches, despite the fact that many move around
echiura
recently moved to his position on tree, used to be sister taxa to annelids
not segmented, but had a segmented ancestor and lost segmentation
clitellata
have clitellum
clitellum
used in reproduction
polychaete
have a lot of setae, generally have parapodia
saltwater only
make up 2/3rds of annelids
errantia
motile polychaetes
sedentaria
sedentary polychaetes, lives in tubes or burrows
lugworm
lives in burrow, eats sand to get food
oligochaete
have fewer bristle/setae than see in the polychaetes and have lost parapodia,
freshwater and moist terrestrial
tubifex
live head-down in tubes, often found in sewer lines
stylaria
long, pointed proboscis
do leeches have a fixed number of segments
yes,
leech characteristics
most freshwater, some marine or terrestrail
have suckers
many with y- shaped, cutting jaw
polychaetes
errant and sedentary forms
over 10,000 described species
mostly marine
polychaetes body form
head well developed, particularly in the errant form
prostomium-
persitomium-
parapodia-
prostomium
in front of mouth, basically the head, doesn’t contain mouth, has sensory structures,
persitomium
first body segment, behind the head, contains the mouth,
parapodia
paddle like appendages that bear the setae
errant polychaetes
free living
jaws
scavengers or predators
sedentary polychaetes
tubes or burrows
filter or deposit feeders
filter feeders
specialized segments that look like fans and move water,
generate mucous to capture food particles and transport it to the mouth
deposit feeders
tentacles that extend from burrow to gather particles or suck water and sediment into burrow to get food particles out of sand
olychaete reproduction
dioecious
most sexual reproduction, some asexual
external fertilization
no distinct gonads, masses of developing gametes develop as swelling of peritoneum in some segments
how do polychaetes gametes develop in some
gametes develop in a chain of segments called an epitoke
what kind of larvae do polychaetes have
trochophore larvae
atoke
stays in sediment (can create new epitoke for next spwaning period/season)
how do polychaetes know when to swarm
by lunar phase, pheromones, water temperature, or combination
what is synchronous spawning good for
increasing chance of fertilzation in broadcast spwaners
why is synchronous spawning bad
attracts a lot of things trying to eat
oligochaetes
few setae
lack parapodia
>3,000 species
freshwater, terrrestrail, a few marine or parasitic
what is setae used for during locomotion
used to anchor self
oligochaetes response to stimulus
cephalization
in some species the prostomium is prehensile and can be used to drag things like grass and leaves into their burrow
cephalization
paired ganglia make up the brain, connect to ventral nerve cord which has paired ganglia in each segment for coordination, generally more adapted for a burrowing lifestyle (some non-burrowing forms have tentacles on prostomium)
oligochaete reproduction
monoecious clitellum true gonads mostly sexual reproduction direct development (no larval stage)
oligochaete sexual reproduction
bring ventral surface together, mucocus secreted by clitellum and setae hold them together
sperm is discharged form genital opening and moves through seminal grooves on outside of body to the seminal receptacle of the other individual, after sperm exchanged, worms part way
what do oligochaete do after sexual reproduction
each worm produces a mucous band around clitellum, then a tougher band around that to form a cocoon with mucous inside
cocoon slide forward over head
as it passes oviduct it picks up eggs, and as it passes seminal receptacle picks up sperm from other worm
where does embryonic development take place
in cocoon until young worms hatch
have direct development no larval stage because they are on land
hirudinea
leeches 700 species mostly freshwater no setae (few exceptions) lack septa between segments anterior and posterior suckers bloodsuckers secrete anticoagulant (hirudin), lack digestive enzymes
what takes up most of the inside of leeches
connective tissue and muscle
do leeches burrow
no
what is the anterior suckers for in leeches
feeding
what is the posterior suckers for in leeches
for attachment and leverage
anticoagulant
hirudin
can leeches secrete anesthetic
yes,
what do leeches rely on for digestion
bacteria
leeches in medicine
problem- microsurgical procedures that restore arteries, but not delicate veins
solution: leeches vasodilation anticoagulant anethetic cheap cool
leech reproduction
monoecious true gonads sexual reproduction internal fertilization direct development often a higher level of parental investment
when is clitellum present in leeches
only during breeding season, secretes cocoon for eggs and sperm, development occurs inside cocoon
where can leech cocoon be attached
to submerges objects or buried, some keep cocoon attached to ventral surface of parent for protection
