Flatworms, Nematodes and Arthropods Flashcards
1
Q
Life cycle of beef tapeworm
A
- final/definitive host
- growth and dispersal of parasite in faeces
- ingestion by intermediate host (pig)
- becomes bladderworm in pig muscle, eaten by human in undercooked meat
- becomes adult tapeworm in humans
2
Q
Cestoda scolex
A
method of attachment to intestinal crypts
3
Q
Cestoda neck
A
generates new proglottids
4
Q
Cestoda immature proglottids
A
immature reproductive organs
5
Q
Cestoda mature proglottids
A
mature male and female organs
6
Q
Cestoda gravid proglottids
A
Uterus with fertilised eggs which detach and pass out in host faeces
7
Q
Cestoda strobila
A
Neck and proglottids which range in size from a few mm to >20m
8
Q
Clades of Metazoa (5)
A
- Parazoa (Porifera)
- Eumetazoa (Radiata + Bilateria)
- Lophotrochozoa
- Ecdysozoa
- Deuterostomia
9
Q
Structure (3) and characteristics (2) of Parazoa
A
- “Pore bearers”
- Body plan is a loose federation of cells in a gelatinous matrix
- Lack tissues and a true digestive system
- The simplest animals
- Filter feeders
10
Q
Characteristics of Eumetazoa (1)
A
- separated into radial and bilateral based on body symmetry
11
Q
Structure (5) and characteristics (2) of Cnidarians (radial eumetazoa)
A
- Stinging/nettle animals
- True tissues
- No brain
- Nerve + contractile filaments
- Gastrovascular cavity
- VENOMOUS PREDATORS
- Categorised into polyps or medusa
12
Q
Examples of Polyps (2)
A
- Hydrozoa
- Anthozoa (corals and anemones)
13
Q
Examples of Medusa (2)
A
- Scyphozoa (jellyfish)
- Cubozoa (box jellyfish)
14
Q
Characteristics of Myxozoa (3)
A
- Cnidarians (Eumetazoa)
- Radially symmetric
- ALL parasitic
15
Q
Benefits of bilateral symmetry
A
- Motor coordination (forward, direction motion)
- Allows for cephalization
16
Q
Define cephalization, and what has it lead to (4)?
A
- Formation of a head region
- Sensory structures
- Brain development
- Mouth at cephalic end
17
Q
Bilateria are ___blastic organisms
A
triplo (blastic)
18
Q
Define triploblastic
A
Consisting of 3 germ layers
- ectoderm
- mesoderm
- endoderm
19
Q
What are the advantages of being triploblastic? (2)
A
- specific tissues
- greater diversity and complexity
20
Q
What tissues are in the ectoderm?
A
- skin, hair and nails
- mouth lining
- tooth enamel
- brain and nerves
21
Q
What tissues are in the mesoderm?
A
- kidneys
- gonads
- circulatory system
- notochord
- muscles
- body cavity
22
Q
What tissues are in the endoderm?
A
- GI tract lining
- respiratory tubes
- liver
- pancreas
23
Q
Phyla of Lophotrochozoa (features of the mouth)
A
- Platyhelminthes
- Mollusca
- Annelida
- Acanthocephala
24
Q
Structure (4) and characteristics (3) of Platyhelminthes (flatworms)
A
- no body cavity
- no circulatory system
- simple gut
- no anus
- have gaseous exchange across surface
- motile and predatory
- reproduce sexually or asexually
25
Groups of Platyhelminthes
1. Turbellaria
2. Monogenea
3. Trematoda
4. Cestoda
26
Characteristics of Turbellaria (4)
- In phylum platyhelminthes, lophotrochozoa
- Parasites or commensals
- Mostly free living
- Have a ciliated epidermis
27
Example of Turbellaria
Planaria
- Are able to regenerate when cut
28
Characteristics of Monogenea
- obligate ectoparasites of fish
29
Structure (3) and characteristics (4) of Trematoda
- Flat, leaf like bodies
- Attach to mucosal wall with suckers
- Hermaphrodite reproductive system
- Obligatory endoparasites
- Flukes
- Adults live in vertebrate intestine
- 2 or more hosts
30
Example of Trematoda and life cycle
*Fasciola Hepatica* (Liver flukes)
- Affect a wide range of grazing animals
- Drink blood
- Pass in faeces via egg
- Larva enters snail and asexually reproduces
- Cercaria (2nd larva) exit snail, find a plant, animal eats plant
- Excysts in intestine, moves to liver where it is a sexually mature fluke
31
Schistosomes and importance
- Blood flukes of humans all
domestic mammals
- 2nd most important parasite
after malaria
32
Difference between fasciola and schistosomes:
Schistosomes are:
a) Dioecious (have separate sexes)
b) Use active entry to final host (skin, ingestion)
33
Which parasites commonly use a snail as their intermediate host?
- Fasciola hepatica
- Schistosomes
34
The class cestoda are otherwise known as
Tapeworms
35
Characteristics of cestoda
- Parasites of small intestine of vertebrates (high nutrient environment)
- Tape-like body
- Nutrients absorbed across body surface
- Reproductive System replicated as chain
36
What do cestoda lack?
Mouth, digestive tract or anus
37
Cestoda scolex
Attaches in intestinal crypts
38
Cestoda neck
Where generation of new proglottids occurs
39
Immature proglottids
Reproductive organs not fully developed
40
Mature proglottids
Mature male and female organs
41
Gravid proglottids
Uterus with fertilised eggs which detach and pass out in host faeces
42
Strobila
Tapeworm neck + proglottids; can be from a few mm to >20m long
43
Life cycle of the beef tapeworm of humans
1. Final / definitive host in intestine
2. Dispersal of parasite
3. Digestion of parasite by intermediate host (cow/pig)
4. Forms bladderworm in muscle which is eaten by humans
5. Larval scolex attaches to intestine of human
44
*Echinococcus granulosus* and life cycle:
Hydatid tapeworm: one of smallest cestodes of domestic animals
- Its definitive hosts include dogs, dingos, and foxes
- Intermediate hosts include sheep, cow, marsupials, and humans (and many other mammals)
- The new final host infected by ingesting contents of hydatid cyst from raw offal of infected intermediate host
45
Lophotrochozoans are split into 6 phylum of note:
1. Phylum Platyhelminthes (no body cavity)
2. Phylum Mollusca and Phylum Annelida (with a body cavity)
3. Molluscs - non segmented
4. Annelids - segmented
5. Phylum Acanthocephala
46
Acoelomates include
Flatworms
47
Phylum Acanthocephala
- Bilaterian organisms with a 2 host life cycle - arthropod intermediate host and vertebrate definitive host
- Have no gut
- Can invert inside out
48
Proboscis are ___ used by ___ to ...
Spinous structures; acanthocephala; penetrate mucosa
49
*Macracanthorhynchus hirudinaceus* importance and life cycle
Type of acanthocephala worm found in wild pigs in Australia
- Adults in SI of pig have separate sexes
- Eggs pass with faeces
- Eggs ingested by beetle larva
- Larva eaten by pigs
- Proboscis penetrates mucosa
50
Phylum Mollusca includes
- Chitons
- Gastropods
- Bivalves
- Cephalopods
51
Clade Ecdysozoa includes phyla ___ and ___, and is characterised by..
Nematoda and Arthropoda
- Ability to shed their exoskeleton
52
Nematoda are also known as
Roundworms
53
Nematodes are ...
- Usually microscopic <1mm
- Interstitial dwellers (fresh water & marine sediments, soil)
- Decomposers
- Triploblastic
- Many parasites of plants, animals, humans
- Non-segmented with a cylindrical body that is tapered at both ends
- Moulting
- Dioecious, with sexual reproduction and internal fertilisation
54
Physical characteristics of nematodes:
- A body wall lined by thick cuticle secreted by underlying epidermis
- Bbody with longitudinal
muscles only
- No respiratory or circulatory
system, internal transport via
body fluid
- A “complete” gut with mouth, anus
55
What is the body cavity of nematodes called?
Pseudocoelom
56
Which animals are acoelomate?
Platyhelminthes (Flatworms)
57
Which animals are coelomate?
Annelids, molluscs, arthropods, echinoderms, chordates
58
Which animals are psuedocoelomate?
Nematodes (Roundworms)
59
*Haemonchus contortus* classification and importance
Nematode
- "Barber’s pole worm"
– Blood feeder, by blood-letting
- Major pathogen (parasite) of sheep
- Occurs in summer rainfall areas (Qld, northern NSW)
- Resistance to anthelminthics (anti-worm) treatments well entrenched
- Some regions (eg South Africa) can’t sustain flocks due to drug resistant strains of parasites
60
Life cycle of *Haemonchus contortus*
- Adult worms in abomasum of sheep
- Eggs pass with faeces
- 1st Stage larvae (L1) hatch and feed on bacteria in faeces
- Moult to L2 and then L3 in faeces
- L3s migrate in moisture away from faeces by climbing grass blades
- Sheep infected by eating grass with L3s
61
Important nematode parasites
- Dog hookworm *Ancylostoma caninum*
– Human hookworms *Necator americanus* and *Ancylostoma caninum*
62
Ascaris importance
- Large intestinal worms of mammals
- Cause disease by occluding intestine
and because of aberrant migration in
host
- Females lay desiccation-resistant eggs
- Ascaris suum in pigs
- Ascaris lumbricoides in humans
- Parascaris equi in horses
- Toxocara canis in dogs
63
Generalised hookworm life cycle
- Adults mature in small intestine
- Eggs pass in faeces
- Larvae hatch and develop in soil and then attach to grass blades
- Larvae penetrate skin of host and enter bloodstream until they reach the heart
- Larvae enter lung capillaries and alveolar spaces, migrate up the trachea and are swallowed
64
Parascaris equorum life cycle
- Adults in Small Intestine of horse
- Egg in faeces mature but do not hatch
- Eggs ingested by horse - usually foal
- Larva hatches in Small Intestine
- Larva burrows into wall of SI, finds blood vessel
- Travel to lungs and burst into alveoli
- Travel up tracheae and are swallowed
- Eggs can survive on pasture for years
65
*Dirofilaria immitis* and life cycle
Dog heartworm
- Adult worms in pulmonary artery of dog
- Adult worms produce infective stage
- Microfilaria...L1s still encased in sheath (eggshell?)
- Microfilaria in blood ingested by mosquito
- Microfilaria develop to L3’s in muscle and migrate to salivary glands and mosquito mouthparts
- Mosquito vector transmits heartworm with blood meal
66
Phylum Nematomorpha
- Horsehair worms
- Larvae are parasitic and drive insects to water when mature to burst from host and escape into water.
- Adults mate in large aggregations-
“Gordioidea”
67
Acoelomate
Have no body cavity
68
Coelomate
Have a body cavity
69
Pseudocoelomate
Intermediate body cavity with mesoderm only on one side
70
What are the benefits of having a body cavity?
- Independent movement of body wall and enclosed organs
- More space allows for larger size
- Storage for eggs/sperm
- Coelomic fluid protects internal organs
- Some have circulatory function
- Waste removal
- Hydrostatic skeleton
71
What are some key groups in the phylum annelida?
- Oligochaete
- Hirundinea
- Polychaete
72
Annelid translates to..., therefore annelids are ___ lophotrochozoans
Little rings; segmented
73
What are the benefits of segmentation?
- Better control of body sections
- Diversification of function
74
What does ecdysis mean?
Shedding of the exoskeleton that arthropods must undergo in order to grow
75
Do nematodes have a circulatory system?
No
76
Do nematodes have a respiratory system?
No
77
Which of the following classes from phylum Platyhelminthes is of vet importance?
a) Turbellaria
b) Monogenea
c) Trematoda
d) Cestoda
C and D
78
Hermaphrodite
An individual that functions as both male and female in sexual reproduction by producing both sperm and eggs
79
Within clade lophotrochozoa, which of the following clades have a body cavity?
a) Phylum Platyhelminthes
With a body cavity
b) Phylum Mollusca
c) Phylum Annelida
B and C
80
How are insects infected with Nematomorpha?
When drinking water
- When worms mature, they
induce host to go to water and
burst from host body
81
What are the major roles of arthropods in the environment?
- Predation, prey, parasites, symbionts
- Pollinators
- Decomposers, scavengers
82
What makes arthropods so "successful"?
1. Very adaptable body plan
2. Ability to thrive in a range of environments
3. Body segmented
4. Segments then have become fused allowing even greater control of body regions and specialisation (head, thorax, abdomen)
5. Exoskeleton with jointed appendages
83
The fusion of body segments is known as ___, which produces ___
Tagmatisation; tagmata
84
What are the features of arthropods?
- Exoskeleton
- Segmentation
- Tagmata
- Appendages
- Respiratory structures
- Open circulatory system
- Ventral nervous system
- Complex excretory system
- Sexual reproduction
85
What are appendages in arthropods?
- “tools” for every purpose including;
- mobility, sensing, feeding and reproduction
86
What are examples of tagmata in arthropods?
- Head, thorax, abdomen
- Head, trunk
- Cephalothorax, abdomen
87
What are the 2 groups of living arthropods based on?
Mouthpart organisation
88
What are the 2 groups of living arthropods?
1. The Chelicerates
2. The Mandibulates
89
Chelicerae
- Paired feeding appendages before the mouth that modified into fangs (spiders) or pincers
- Hollow and carry venom
90
Mandibulates
* Mandibulate mouthparts
– Large mouthpart structures
– Typically used for chewing/grinding
91
Pedipalps
- Second pair of appendages in chelicerates
- Feeding or sensory
92
How many eyes do chelicerates have?
Up to 8 single lens eyes
93
Do chelicerates have antennae?
Not true antennae
94
How many pairs of legs do ADULT chelicerates have?
4
95
What makes up the body of chelicerae?
The cephalothorax and abdomen
96
Name organisms in the chelicerae group
Arachnids: spiders,
scorpions, ticks, mites
97
Name a group of chelicerates of veterinary importance
The ticks (Acarines), which are external parasites of mammals, birds and reptiles
98
Ticks can use how many hosts per life cycle?
1, 2 or 3 host individuals
99
What do ticks feed on, and what happens as they do this?
Blood; they engorge up to 100x their original body size
100
What do ticks use to assist feeding, and how does this impact the harm they can cause?
Saliva; allows ticks to act as vectors of disease causing microorganisms
- Also enables them to secrete neurotoxins
101
Example of a 1 host tick
Rhipicephalus (Boophilus)
australis
- Cattle tick
102
Life cycle of cattle tick
- Female feeds and becomes engorged
- Female lays up to 3000 eggs
- Eggs become larvae, which feed and moult to grow
- Ticks feed and reproduce
103
Why is it so difficult to remove a feeding tick?
Their mouthparts include;
- slicing chelicerae
- denticulate (toothed) hypostome, and also
- adhesive cement in some species
104
Name another chelicerae of veterinary importance
Mites
105
Characteristics of mites
- Most mites are free-living (not parasitic)
- Many are important parasites
scabies mite.
106
What is an important ectoparasitic species of mite?
Scabies mite, which live in burrows on skin
- Go from egg to adult on one host and transmission occurs predominantly by contact
107
What health condition does the scabies mite cause?
- “Mange” – a condition associated with severe dermatitis:
- Characterised by: hair loss, scabs & keratinised skin with mites found in skin scraping
108
How many species do mandibulates form?
Vast majority of species (90-95%)
109
What environments do mandibulates inhabit?
All environments - terrestrial, freshwater, marine
110
What group are the most abundant mandibulate?
Beetles
111
What makes up the body of mandibulates?
Complex bodies with 3 tagmata: head, thorax and abdomen
112
How many pairs of legs do mandibulates have?
3
113
Up to how many pairs of wings can mandibulates have?
2
114
What is a key group in mendibulates?
Hexapods (Insecta)
115
What adaptations do hexapods have for the terrestrial environment?
- Usually small size
- Exoskeleton
- Jointed, hardened locomotory appendages like legs and wings
- Excretory System
- Advanced respiratory system
- Advanced nervous system
- Advanced Sensory system
- Internal fertilisation
- Resistant eggs
116
What makes up the excretory system of hexapods?
- One composed of tubules that pass through body and extract water from wastes
- Nitrogen waste excreted as uric acid
117
What makes up the respiratory system of hexapods?
- Spiracles open to outside.
- Tracheae (tubules) ramify through body and provide direct oxygen supply to tissues.
118
What makes up the sensory system of hexapods?
Antennae and compound eyes
- (also cerci of cockroaches)
119
What is the role of the exoskeleton in hexapods
Provides protection against the environment
120
What is a compound eye?
An eye consisting of numerous small visual units, as found in insects and crustaceans
121
What other group of eukaryotes is insect evolution associated with?
Plants
122
From an evolutionary perspective, invasion of land and appearance
of first hexapods formed
Apterygota
123
Apterygota
Primitively wingless insects with mostly simple mouths
124
Examples of modern day Apterygota
1. Springtails (Collembola)
2. Silverfish (Thysanura)
125
From an evolutionary perspective, evolution of wings in insects formed the group:
Palaeoptera
126
Palaeoptera
- Simple insects with simple
development
- Wings of these insects did
not fold over abdomen
127
Examples of modern day Palaeoptera
1. Dragon flies (Odonata)
2. Mayflies (Ephemeroptera)
128
From an evolutionary perspective, development of wings that fold
over abdomen formed the group:
Orthopteroida
129
Orthopteroida
- Cylindrical body, with elongated hindlegs and musculature adapted for jumping
130
Examples of modern day Orthopteroida
1. Grasshoppers, locusts (Orthoptera)
2. Praying mantis- Mantodea
3. Stick insects- Phasmatodea
4. Cockroaches- Blattodea
131
From an evolutionary perspective, development enhanced innervation formed the groups:
- Hemipteroida
- Neuropteroida
- Hymenopteroida
- Panorpoida
132
Define Enhanced Innervation
- Increase or improvement in the process of nerves connecting with and influencing a specific tissue or organ
133
What are the two lineages of enhanced innervation?
1. Those that maintain simple
development - hemimetabolous
2. Those with complete metamorphosis - holometabolous
134
What is the name of the enhanced innervation lineage that retain simple development:
Hemipteroida - hemimetabolous development
135
What is the life cycle of Hemipteroida?
1. Egg
2. Juvenile forms (nymphs) that look like adults but lack wings and are not sexually mature; Juveniles moult to grow
4. Adults that have wings (often but not in every group or species) and sexual maturity
136
Examples of modern day Hemipteroida
- Lice (Mallophaga, Anoplura)
- Bugs, aphids- Hemiptera
- Plant feeders, but some parasites -
bed bugs, kissing bugs
137
What are the groups from the enhanced innervation lineage that have true metamorphosis
(Holometabolous development)?
1. Neuropteroida
2. Hymenopteroida
3. Panorpoida
138
What is the name for the type of development where insects with enhanced innervation that retain simple development?
Hemimetabolous development
139
What is the name for the type of development where insects with enhanced innervation that retain simple development?
Holometabolous development
140
What is a major characteristic of Holometabolous Development?
Separation of activities during life cycle;
- Egg
- Larva
- Pupa
- Adult
141
What are the advantages of Holometabolous Development?
- Allows adults to occupy a completely different habitat from the larvae;
- Enables larvae and adults to exploit different food resources (if adults feed)
- Metamorphosis allows insects to escape from temporary habitats before conditions become unfavorable for survival.
142
Examples of modern day insects with holometabolous development (true metamorphosis)
1. Butterflies
2. Moths
3. Beetles
4. Weevils
5. Fleas
6. Flies
7. Mosquitoes
143
What is the unifying feature of Ecdysozoa?
They undergo ecdysis during development
144
Life stages in true metamorphosis
- Larva
- Pupa
- Adult
145
Pupa stage in true metamorphosis
- Transitional phase
- Larva moults to grow
146
Larva stage in true metamorphosis
- Feeding, growth and development
147
Adult stage in true metamorphosis
- Reproduces
- Disperses and lays eggs that hatch into larvae
