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