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Invertebrate Zoology Exam 2 2021
Terms in this set (186)
Characteristics of Platyhelminthes
Acoelomate, bilateral symmetry, dorsoventrally flattened, triploblastic, cephalization, organ systems, hermaphroditic, protonephridia, primitive nervous system, yolk gland, four classes
lacking a body cavity, filled with mesenchyme or parenchyma cells
bilateral symmetry in platyhelminthes
leads to anterior and posterior, dorsal and ventral
Shape of Platyhelminthes
dorsoventrally flattened body; triploblastic
dorsoventrally flattened body in Platyhelminthes
allows for diffusion across the body into the cells
3 germ layers of platyhelminthes
ectoderm, endoderm, mesoderm
having 3 germ layers
Digestive system of Platyhelminthes
gastrovascular system- absent or incomplete digestive system
Muscular system of Platyhelminthes
rigid skeletal elements, has longitudinal, circular and transverse muscle fibers
Respiratory system of Platyhelminthes
lacks a complete system; diffusion of O2, CO2, and ammonia through the body wall
monoecious; most flatworms fall here; have cross fertilization and internal fertilization
What flatworm is not hermaphroditic?
Protonephridia of Platyhelminthes
excretory structure similar to a kidney to get rid of nitrogenous waste; involved in many circumstances of osmoregulation; flame cell
system of tubes capped by a cell
Whey is it important that protonephridia is involved in circumstances of osmoregulation?
important for planar living in a hypotonic environment
Nervous system of platyhelminthes
some have a nerve net with no ganglia, some have a pair of ganglion and 1 or several pair of longitudinal nerve cords (with ladder like appearance)
What platyhelminthes does not have a ganglia/brain?
Vitelleria of Platyhelminthes
yolk gland; summer eggs have thin walls and hatch in 2-3 weeks; autumn or dormant eggs have thick resistance walls; resists cold and desiccation
Four Class of Platyhelminthes
Turbellaria, Trematoda, monogenesi, Cestoda
platyhelminthes with no cilia and no gut
Free-living flatworms; predators and scavengers, meat eaters
Habitat of Class Turbellaria
marine, freshwater and moist terrestrial environments
Intestine of Class Turbellaria
sac-like or branched in some; incomplete gut; digestion is extracellular or intracellular through phagocytic cells
Movement of Class Turbellaria
ciliated epidermis, muscles, and slime (mucous film) trail that is secreted by the epidermis
Sensory devices of Class Turbellaria
Eyespots and Auricles
Eyespots of Class Turbellaria
light sensitive, negatively phototaxis ( they don't like light)
Auricles of Class Turbellaria
sensory lobes for chemoreception
Reproduction of Class Turbellaria
Asexual through transverse fission or generation; sexual through cross fertilization
body splitting; mesenchyme is the source of the new cell differentiation, reproduction can be controlled by day length and temperature
Types of symbiotic relationships in Class Turbellaria
symbiosis, mutualism, commensalism, parasitism
both get something out of it
"eating at the same table;" one benefits, the other isn't harmed
85% of the 13,000 flatworms are parasites, tendency to have a complex lifestyle
8000+ species of flukes, economically and medically important; have suckers and mouth; branched intestine
Parasitism of Class Trematoda
ecto and endo types; obligate parasites (not free living)
Class Trematoda; has 2 intermediate hosts
Life Cycle of Flukes
Egg (operculated) -> miracidia (ciliated larvae) -> sporocyst (sac-like structure) -> rediae (pharynx & sac-like intestine) -> cercariae (digestive tract, suckers, tail) -> metacercariae (encysted structure, hatches in intestine)
Class Trematoda, Chinese liver fluke, Egg -> miracidium -> first intermediate (snail) -> cercaria -> second intermediate (fish)
Fasciloa (Sheep Liver Fluke)
Class Trematoda, F.hepatica, intermediate is the snail, metacercaria form on water vegetation, fairly large species of fluke, widespread
Shistosoma (Blood Fluke)
Class Trematoda; causes schistosomiasis or bilharzia, found in Africa, S. America or the Far East; humans, and snails are hosts; 3 different species; second largest impact on human species only to Plasmodium
Shistosome fluke life cycle
infections occur when humans contact contaminated water; cercariae burrow through the skin; migrates into circulatory system into the vessels of the mesentery or bladder; adult worms live in the vessels producing eggs that pass through the intestinal or urinary tract; eggs hatch in water and snail acts as an intermediate host
found in USA; won't complete life cycle in humans, but can cause itchiness on skin
Class Trematoda; lives in gallbladder/bile ducts of definitive hosts (herbivores)
Life cycle of Dicrocoelium dendriticum
occurs entirely on land; eggs are eaten by suitable snail; mercaridae is released inside of the snail and eventually leads to cercariae; ends up in slime ball, then delivered to ant and forms metacercariae, ant attaches to grass and cow eats grass
main class is Cestoda; subclasses Cestodaria and Eucestoda
tapeworm; subclasses Cestodaria and Eucestoda; 3500 species
Class Cestoda; tapeworm, no gut/scolex/proglottids, hooks in larvae
Class Cestoda; true tapeworms; highly specialized, parasitic, lack digestive system
How do Eucestoda get nutrients?
absorb them across the body wall; they lack a mouth/digestive tube
Body tegument of Eucestoda
Microtrichia (microvilli) function to increase surface area for absorption to occur
microvilli, small projections that can only be seen at high power
Size of Eucestoda
extremely varied; 1mm to 15M
What is the physiology of Eucestoda devoted to?
producing large quantities of eggs through cross fertilization
Body parts of Eucestoda
scolex, proglottid, immature proglottid, mature proglottid, gravid proglottid, strobila, genital pore
not a head; typically has an attachment organ or holdfast, possibly hooks or suckers
reproductive bud on tapeworm
smaller reproductive bud on tapeworm
larger reproductive buds, can see ovaries/testes here
even more mature, full of eggs; they break off and pass out with fecal matter
string of proglottids in tapeworm
fish tapeworm; occurs in N. America in pike/walleye; definitive hosts can be humans or carnivores
Life cycle of Diphyllobothrium latum
embryonate egg in water; coracidnium ingested by crustaceans; plerocercoid ingested by fresh water fish; plerocercoid is in the muscle of fish which is ingested by the carnivore/human; scolex attaches to intestine and grows into adult; embryonate egg is excreted in feces and travels back to water
Where does diphyloobothrium latum occur?
in areas where lakes/rivers coexist with human consumption of raw/undercooked freshwater fish
Symptoms of Diphyllobothrium latum
usually asymptomatic; can include abdominal discomfort, diarrhea, vomiting and weight loss
What are the definitive hosts of the beef and pork tapeworms?
What are the intermediate hosts of the beef and pork tapeworms?
cows and pigs
Life Cycle of Beef and Pork Tapeworm
embryonate egg gives rise to oncosphere; oncosphere burrows through to the circulatory system and gets to the muscles of the body; then the cysticercus is formed and can survive in the animal for many years
beef tapeworm; humans are the only definitive hosts; adults reside in small intestine
How long are taeniarhyncus saginata?
typically 5m or less in length, but can reach up to 25m
How many proglottids and eggs do taeniarhynchus saginata have?
1,000-2,000 proglottids, with 6 being released per day; 80,000-100,000 eggs per proglottid
How do cattle and herbivores become infected with taeniarhynchus saginata?
by ingesting vegetation contaminated with eggs or proglottids
How are humans infected with taeniarhynchus saginata?
by ingesting raw or undercooked infected meat
How do cysticercus develop in the human intestine?
develops over 2 months into an adult tapeworm, which can survive for more than 30 years
Where is taeniarhynchus saginata found?
pork tapeworm; can cause cysticercosis and humans can become the intermediate hosts
Where are Taenia sodium found?
worldwide distribution; more prevalent in poorer communities where humans live in close contact with pigs and eat undercooked pork; very rare in Muslim countries
What is the length, number of proglottids and eggs of Taenia solium?
2-7m in length, less than 1000 proglottids, 50,000 eggs per proglottid
How long does a taenia solium live?
up to 25 years
Where do taenia solium develop?
in humans, and other animals such as monkeys and hamsters
develops in striated muscle as well as the brain, liver and other tissues of pigs, other animals and humans
How do humans develop taeniasis?
when they ingest undercooked pork containing cysticerci
dog tapeworm; other hosts include cats, foxes and humans (mostly children)
Life Cycle of Dipylidium caninum
flea picks up egg, flea is on dog, dog ingests flea with embryonate egg and becomes infected, goes into intestine and develops into adult
How many genital pores does Dipylidium caninum have?
two per segment
How long are dipylidium caninum?
up 60cm in length and 3mm in width
How does the vertebrate host become infected with dipylidium caninum?
by ingesting the adult flea containing the cysticercoid
found in the US, carnivore is the definitive host; herbivore (& sometimes human) is the intermediate host
Where is Echinococcus granulosus found?
not just the muscle, but also the vital organs; the adult is found in the small intestine
How long is Echinococcus granulosus?
the adult is 3-6mm long
definitive hosts are foxes and sometimes dogs, cats, coyotes and wolves
rodents are intermediates
wild felines are the definitive hosts; rodents are intermediates
human tapeworm; 15-40mm in length, has a small, rounded scolex and proglottids
Life cycle of Hymenolepis nana
infected by consuming embryonate egg; passes through intestine; larvae emerges into intestinal lining; comes back out and matures into adult; adult comes out and sends out more proglottids/eggs
Is there a vector involved with Hymenolepis nana?
No, if you get this it is because you've picked up the eggs from another human
ribbon or nemertine worms; similar to flatworms; approximately 800 species, acoelomate
Habitat of phylum Nemertea
burrows in sand, mud and under rocks in shallow water
Protonephridia of phylum Nemertea
osmoregulation, excretion in marine worms
Ciliated epidermis of phylum nemertea
gland cells that secrete mucus, muscles play an important role in locomotion
Bilateral nervous system of phylum nemertea
ganglion and longitudinal cords
What type of bodies do phylum nemertea?
Proboscis of phylum nemertea
shot out of the body utilizing muscle contractions, reversible and used for capturing prey; all members of this phylum have it
cavity filled with fluid with a sheath of circular muscle; has a rhychodeum
canal between proboscis pore and the beginning of proboscis
calcareous piercing structure; barb; can have toxin or venom
replaces the stylet if it is broken
If those in phylum nemertea don't have a stylet, what do they have?
a sticky proboscis
Is the proboscis associated with the digestive tract?
no, there is no association
What type of eaters are phylum nemertea?
carnivores (annelids, crustaceans)
What type of digestion does phylum nemertea have?
complete digestive tract; regional specialization; advanced over turbellarians
Explain the circulatory system of phylum nemertea
closed and well defined; no true heart; blood is colorless; amebocytes present
What size are phylum nemertrea?
varied in size; <20cm, 1-2M, largest recorded was 30M
What type of reproduction do phylum nemertea have?
asexual through fragmentation and sexual through external fertilization
phylum nemertea; unarmed worms in which the proboscis lacks a stylet and the mouth is usually posterior to the brain; Eg. Cerebratulus
phylum nemertea; the mouth is anterior to the brain and have a proboscis that may be armed
roundworms; widespread and abundant
phylum Nematoda; no peritoneum; fluid filled; act as a hydrostatic skeleton
What type of digestive system do phylum Nematoda have?
tubular digestive system
a fixed set of cells from the time of fertilization; found in phylum nematoda
What systems do phylum Nematoda lack?
circulatory (no blood vessels), respiratory (happens across body wall)
present in phylum Nematoda; non-living structure secreted by the epidermis; made of scleroprotein which prevents it from being broken down or digested
How abundant are phylum Nematoda?
there are approximately 5 billion/acre
How does phylum Nematoda feed?
carnivores, herbivores, omnivores and blood feeders
Does phylum Nematoda have osmoregulation or excretion?
the location determines which one they have
glandular system in phylum nematoda
Reproduction in phylum Nematoda
dioecious; eggs shed or living yolk
Where are the ovaries/testes found in phylum Nematoda?
the thinnest part of the body
causes ascariasis; worldwide distribution; approximately 25% of the population is affected
How can you get Ascaris lumbricoides?
can get it from fecal contamination
How long are Ascaris lumbricoides?
can reach up to 49cm, female is typically longer than the male
What is the host of the Ascaris lumbricoides?
human host; fecal-oral route; only passed between humans
Characteristics of Ascaris lumbricoides eggs
light-weight and resistant to the environment; some are viable after 10 years; embryo takes about 2 weeks to form
Symptoms of ascariasis
pneumonia, abdominal pain, intestinal blockage
pinworm; most common parasitic roundworm in the US; fairly small
What is the host of Enterobius vermicularis?
humans; primarily children
Are the eggs of Enterobius vermicularis resistant?
Life cycle of Enterobius vermicularis
fecal oral route: human consumes eggs, adults form, produce eggs pass out in fecal material; often spread by children's bedding or clothing
dog ascarid worm; dog swallows eggs and larvae migrate
Can dogs develop immunity to Toxocara Canis?
yes, typically in the span of 3-4 months
What do Toxocara Canis look like?
male looks like ascaris, has a hook tail
infections are widespread in humans; humans are definitive hosts; no vectors; does not travel through oral fecal route
hookworm found in North Africa, Europe, India, China and Japan; sharp teeth; primarily occurs in organisms that consume meat
hookworm found in the Southern U.S., Central and South America; has cutting plates; most important in tropics; prolific egg producers; feeds on RBC and tissue
How many eggs does nectar Americans produce in a day?
How does someone contract Ancylostoma duodenale or Nectar americanus?
walking barefoot the larvae burrows through the skin to get into the body
Life Cycle of Ancylostoma duodenale or Nectar americanus
larvae burrows through skin; travels to circulatory system; travels to heart and lungs; ends up in small intestine; adults can live up to 2 years inside the body
What do Ancylostoma duodenale or Nectar americanus secrete while feeding on blood?
an anticoagulant; 1 worm in responsible for 1cc/day blood loss
What can blood loss from hookworms lead to?
anemia in humans which leads to lack of energy and lethargy; 25 worms will lead to hookworm disease; can have black/tarish stool; tuberculosis may result from lung disease
How can we prevent the contraction of hookworms?
proper sanitation, especially with water
cats and dogs are hosts; larval migration and creeping eruption; lack a complete host; treatment includes the use of ethyl acetate
guinea worm; found in Tropical Africa, Arabia, India, Near East and East Indies; experience burning sensations when they are ready to release larvae
Life cycle of Dracunculus medinensis
infection occurs through consumption of copepods in contaminated water; larvae is released and migrates from intestinal tract to the skin; female produces living young; causes ulceration; blister breaks open; larvae is released into body of water
Prevention for Dracunculus medinensis
education, covered wells, straining devices and netting
whipworm; oral fecal route; lifecycle similar to pinworm; causes little injury to the host; have very distinctive eggs
How many eggs does a female trichuris trichiura lay per day?
pork worm; causes trichinosis in carnivores and omnivores; ovoviviparous; eats anything; has living young; 3 ecological types
How is someone infected with trichinella spirals?
by consuming contaminated pork or bear meat
Life cycle of Trichinella spiralis
migrates; encysts in muscle; produces adults; adults produce larvae; move to circulatory system; move to skeletal muscle; form cysts
3 ecological types of Trichinella spiralis
urban cycle, sylvatic cycle and marine cycle
urban cycle of trichinella spiralis
rat, swine and humans; rodents eat each other; they are eaten in the garbage fed to pigs; pigs contract it and humans eat the contaminated pork
sylvatic cycle of trichinella spiralis
predators and scavengers are hosts; scavenger eats predator; predator eats scavenger; predator dies and is eaten by scavenger
marine cycle of trichinella spiralis
found in seals, walruses, whales, and polar bears
How long is trichinella spiralis viable for in the body?
up to 7-8 years
symptoms of trichinella spiralis
edema around eyes, muscular pain, difficulty in respiration and in using muscles, puffy face, swelling of extremities, damage to nervous system and other organs
What is the treatment for trichinella spiralis?
there is no good treatment for ridding the body of worms
wuchereria bancrofit, loa loa, dirofilaria immitis, onchocerca, dictophyme renale; female is ovoviviparous; parasite is seen in the bloodstream; blood sucking insect is the intermediate host
What do filiarial worms release at birth?
they have a live birth and release microfilaria which is a type of larvae
primarily tropic; adults live in the lymphatic system and causes blockage which leads to tissue damage or edema; prominent at night; does not have a specific vector mosquito like malaria
What disease does wuchereria bancrofti cause?
filariasis or elephantiasis
life cycle of wuchereria bancrofit
infected mosquito bites you; transmits microfilaria into your bloodstream; matures in lymphatic system to produce adults; adults produce more microfilaria that live within the circulatory system
African eye worm; found in Central and West Africa; diurnal (active during the day); transmitted by biting flies
where does loa loa live in the body?
lives in the subcutaneous tissue of humans and baboons; worm migrates through the skin and sometimes across the eyeball
What does loa loa cause?
can lead to swelling of the eyeball from the migration of the worm; this can also be caused by the toxin that is released from the worm
heartworm found in cats/dogs; widespread distribution in mild climates; noctural periodicity
What does dirofilaria immitis cuase?
the heartworms cause blockage in the heart and can lead to heart failure
causes onchocerciosis or River blindess; found in African and the Congo, Guatemala, and Venezuela
What does onchocerca cause?
blindness from the organism migrating to the eye; you have to be bitten several times to be effected
What is causing the damage in onchocerciosis?
the larvae of onchocerca being within the eye
giant kidney worm; female is larger than the male; not typically contracted by humans, more so found in birds, dogs, minks and carnivores; widespread
Does dictophyme renale affect one or both kidneys?
typically only affects one kidney
What is the intermediate host of dictophyme renale?
different types of annelids
Life cycle of dictophyme renale
eggs are laid in kidney; pass out of body through urine; reach water; consumed by annelid; fish consumes annelid; typically goes to crayfish; crayfish is eaten by a catfish; this comes into contact with the definitive host
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