23. Arthropods (Intro) Flashcards
what are the three main groups of arthropods?
- crustaceans
- arachnids
- insects
what is included in the crustaceans?
- crabs
- lobsters
- crayfish
- shrimp
what is included in the arachnids?
- spiders
- scorpions
- ticks
- mites
what is included in the insects?
- beetles
- bugs
- earwigs
- ants
- bees
- termites
- etc
parasitic arthropods are ____-parasites
ectoparasites
do parasitic arthropods have a coelom?
yes
do parasitic arthropods have jointed limbs?
yes - this is where they get their name
are parasitic arthropods segmented?
yes
what is concentrated in the head region?
- their neutral elements
- sensory receptors
- feeding structures
what is the rigid cuticular exoskeleton made of?
- tanned proteins
- chitin
what does the exoskeleton provide?
physical and physiological protection and serves as a place for muscle attachment
are the arthropods that cause harm, due to their venom, considered parasites?
NO
what are the two body parts of arachnids?
- the cephalothorax
- the abdomen
how are legs arranged on arachnids?
there are 8 legs on the cephalothorax arranged in 4 bilateral pairs
do arachnids have wings or antennae?
no
what are the 3 distinct body parts in insects?
- the head
- the thorax
- the abdomen
what does the head of the insect have?
2 antennae
what does the thorax of the insect have?
6 legs arranged in bilateral pairs
Parasitic insect species include fleas, flies and lice which actively feed on ___________ and fluids at some stage in their life‐cycles.
host tissues
how many species of insects are there?
1 million
how many species of arachnids are there?
50 000
why are insects and arachnids very adaptable organisms?
they have rapid and fertile reproduction rates
how do they overcome the problem of growing in a non-expandable exoskeleton?
by molting
what are the stages of development between molts referred to as?
instars
Molting is a complex process and its timing is mediated by _______________________________.
many environmental and physiological cues
what is the reproductive strategy of arthropods?
diecious
is fertilization internal or external for arthropods?
internal
a wide range of mating behaviours, ________ and __________ are involved
insemination
egg production
what does the egg develop into (in most species)
a larva
what is a larva?
a life cycle stage that is structurally distinct from the adult and must undergo metamorphosis (structural reoganization) before it becomes an adult
what does it mean for the metamorphosis to be complete?
involving major changes during a pupation stage
what does it mean for the metamorphosis to be incomplete?
involving gradual changes in nymph stages
what is the life cycle sequence for complete metamorphosis?
egg (hatch)
larva (molt)
pupa (hatch)
adult
what is an example of complete metamorphosis?
the grub‐like larval stages of flies and fleas form cocoon‐like pupae where they undergo complete metamorphosis and emerge as radically‐different adult insects
what is the life cycle sequence for incomplete metamorphosis?
egg (hatch)
larva (molt)
nymph (molt)
adult
what is an example of incomplete metamorphosis?
the larval instars (or nymphs) of lice, ticks and mites undergo incomplete metamorphosis through a series of molts gradually becoming more adult‐like in appearance
what other organisms can arthropods be involved with in parasitic relationships, either as a host or the parasite?
- viruses
- bacteria
- protozoa
- helminths
T/F
•
arthropods are usually ectoparasitic on, or in, the skin of vertebrate hosts
T
define haematophagous
sucking blood
define histophagous
tissue-feeders, and bite or burrow in dermal tissues causing trauma, inflammation and hypersensitivity reactions
how are the two ways that infestations (of arthropods in general) can be transmitted from host-to-host?
either by direct contact, or by free-living larvae or adults actively seeking hosts
when does direct transmission of the infective stages occur?
when hosts come into close contact with each other or share quarters, bedding or clothing
________________, nymphs or adults may cross from one host to another, while ______________ may contaminate shared environments
larvae, nymps or adults
eggs or pupae
what do insects (lice) and arachnids (mites) rely on?
close contact between hosts
how do winged insects (like mosquitoes and flies) find new hosts to feed off of?
by flying to the new host
how do non-flying insects, like fleas, find new hosts to feed off of?
by jumping on passing hosts
what is the mechanism of the botflies?
they do not feed on their host, but instead just deposit eggs which will allow larvae to emerge and feed on host tissues and exudates
how do tick larvae seek hosts?
by actively climbing vegetation and questing for passing hosts
what does “one-host ticks” mean?
when a species completes thei life cycle on the same host
what does two-host or three-host ticks mean?
when ticks detach and drop to the ground and molt before seeking new hosts as nymphs or adults
what are the three main groups of parasitic insect species?
- the jumping fleas (Siphonaptera)
- the winged flies (Diptera)
- the wingless lice (Phthiraptera)
what are the two main groups of parasitic non-spider arachnids?
- the macroscopic ticks
- the microscopic mites
what are ticks?
epidermal parasites of terrestrial vertebrates and may transmit other infections
what are other infections that can be passed by ticks?
- viral
- bacterual
- rickettsial
- spirochaete
- protozoal
- helminth
what do ticks mainly feed on?
blood
what are tick’s mouthparts armed with?
small, backward-facing teeth to aid in attachment
what kind of metamorphosis do ticks undergo?
gradual or incomplete metamorphosis whereby larval and nymphal stages resemble adults
what are the two major families of ticks that are recognized on the basis of morphological features?
- the Ixodidae
- the Argasidae
what can be found in the Ixodidae?
- hard ticks with a tough cuticle with some 650 species that infest mammals, birds and reptiles
what can be found in the Argasidae?
soft ticks with a leathery integument with 160 species that infest mainly birds and some mammals
what are mites?
microscopic arachnids that undergo gradual or incomplete metamorphosis
how many legs do adults or nymphs have in mites?
4 pairs of legs
how many legs do larvae have in mites?
3 pairs of legs
how many species of mites have been described?
30k
what do most parasitic species of mites feed on?
skin or debris or suck lymph, and some burrow into the skin, some live in hair follicles, and some live in ear canals
do lice have wings?
no
T/F
•
lice are dorsoventrally flattened
T
do lice have eyes?
they are reduced or absent
what do lice use to cling?
enlarged tarsal claws
what kind of metamorphosis do all lice undergo?
gradual metamorphosis
are there any free living stages in lice?
no
what is different about the ways in which eggs vs. nymphs or adults stick to feathers and hair?
eggs are cemented
nymphs and adults can cling to them
what are the two orders of lice?
- the Mallophaga
- the Anoplura
what are the two orders of lice classified based on?
on their mouthparts
what is found in the Mallophaga?
- chewing/biting lice with some 3000 species infesting birds and mammals
what is found in the Anoplura
- sucking lice with 500 soecies found on mammals
in which way are fleas flattened?
bilaterally-flattened
do fleas have wings?
no
who has special hind legs and what is special about them?
fleas - they are enlarged hind limbs, specially adapted for jumping
do fleas undergo complete metamorphosis? what happens?
yes, grub-like larvae form pupae from which adult fleas emerge
are the larvae of fleas parasitic?
no, they feed on debris associated mainly with bedding, den or nest material
which flea stage is parasitic and what does it feed off of?
the adult stages are parasitic and feed off of host blood
how many flea species are there?
2,500
who are most flea speacies parasitic to?
mammals (especially rodents)
some birds
are flies and mosquitoes winged-insects?
yes
how many pairs of wings do flies and mosquitoes have?
two pairs
what are flies and mosquitoes wings attached to?
the thorax
are the sensory organs of flies and mosquitoes well-developed?
yes
do flies and mosquitoes have feeding organs?
yes
what kind of metamorphosis do flies and mosquitos undergo?
complete metamorphosis
how many species of flies and mosquitos are there?
120,000, belonging to 140 families
what are the two main suborders of flies and mosquitoes?
- Nematocera
- Brachycera
what are the suborders of flies and mosquitoes recognized based on?
structural differences
what is found in the Nematocera
- adult stages are parasitic
- larval stages often free-swimming
what is found in the Brachycera?
- adult stages parasitic or free-living
- larvae stages often predaceous
