Phylum Athropods Flashcards
Taxonomy in order including: subphylum, superclass, and subclass
kingdom
phylum
subphylum
superclass
class
subclass
order
family
genus
species
what taxonomic groups of arthropods are recognized
1)subphylum trilobita
2)subphylum chelicerata- class merostomata (horseshoe crab) and class arachinda (spiders, ticks, mites, scorpions)
3)subphylum crustacea (crab lobster crayfish)
4)Subphylum myriapoda- class chilopoda (centipedes) and class diplopoda (millipedes)
5)subphylum hexapoda- class insecta
is the largest phylum arthropods?
yes
75% of known animal species
what is first reason for arthropod success
-exoskeleton (cuticle) with flexible joints,
secreted by the epidermis
-primarily chitin (a tough, resistant, nitrogenous
polysaccharide that is insoluble in water, alkalis,
and weak acids)
-cuticle is flexible but affords protection,
particularly against dehydration
-Calcium salts in cuticle of crustaceans
what is major disadvantage of arthropod exoskeleton
must be molted since its not alive and cannot grow
second reason for arthropod success
segmentation and appendages for more efficient locomotion
how are the appendages unique
they’re jointed
hollow lever moved by internal muscle
gives them great strength
third reason for arthropod success
air piped directly to cells
terrestrial arthropods have a highly efficient tracheal
system which delivers oxygen directly to the tissues
and cells
high metabolic rate possible
Disadvantage: limits
body size
what is used in aquatic species respiration
gills
fourth reason for arthropod sucess
highly developed sensory organs
keenly alert to surroundings
fifth reason for arthropod success
complex behavior patterns
sixth reason for arthropods success
metamorphosis
what are the two kinds of metamorphosis
holometabolous (“complete change”) and hemimetabolous
(“half change”)
also called complete and incomplete metamorphosis
how does this phylum excrete waste
gills through which nitrogenous wastes are lost via diffusion
what glands are used for osmoregulation
antennal glands aka green glands
what type of excretory/osmoregulatory do terrestrial arthropods have
have Malpighian tubules
what is circulatory system in aquatic forms such as crayfish
open circulatory system with heart and arteries but no veins
What is the circulatory system in terrestrial forms
such as insects and spiders?
Open circulatory system
pump : dorsal vessel, moves blood by peristalsis
extent of arteries varies, no veins
pumps hemolymph (blood), consisting of plasma and amebocytes
mouthparts found among insects (3)
biting or chewing (grasshopper)
sucking (mosquito)
sponging and lapping (house fly)
some insects combine these
Evolutionary relationship between
annelids and arthropods?
rocophore larvae evidence for annelid/mollusc
relationship
RNA evidence does not show close relationship
between annelids and arthropods
there is active research in this area
segmentation of annelids and arthropods may be
homoplasy or homology, research ongoing
What subphylum and class are horseshoe crabs?
Chelicerata
Why are they called chelicerata?
because they possess chelicera, the first pair of head appendages, used to seize prey
what are in subphylum Chelicerata, class Arachnida
mites, ticks and spiders and scorpions
what is chelicera
used to kill prey/pierce food source
poison fangs in spiders
what are pedipals
paired head appendages used as legs, pincers or feeder
what glands make silk in spiders
silk glands
silk glands make silk, which is then emitted as liquid by what
spinnerets
what is sexual dysmorphism in spiders
males have specialized pedipalps used for sperm transfer
males are small compared to female
how do spiders have sex
male spins small web and deposits sperm which is then sucked into modified pedipalps
male courts female with ritualized movements and insert pedipalp into the seminal receptacle of female
class Arachnida what are the two major parts of a spiders body
cephalothorax and abdomen
how many eyes and legs to Arachnida have
8 eyes
8 legs
what are two spiders in US that are dangerous
black widow and brown recluse
what does black widow release
neurotoxin
what does brown recluse release
necrotic
how do scorpions differ in structure from spiders
short cephalothorax, pre-abdomen and post abdomen of 5 segments which ends in a stinging telson
small chelicerae and enlarged pincer-like pedipalps
class Arachnida order acari what are they
acari-mites and ticks
how are acari medially and economically
second only to mosquitoes as disease vectors
carry apicomplexans, viral, bacterial and fungal organisms
some very serious ag pests belong in the group
how do ticks and mites differ from all other arachnids?
complete fusion of the cephalothorax and abdomen, with no signs of external segmentation
most have 4 pairs of legs like other arachnids
what tick carry lyme disease
deer tick
order acari-mites
how are they mammalian pests
chiggers are mite larvae that cause dermatitis and transmit disease, some cause mange
most are free living
Subphylum Myriapoda
what is class Chilipoda
what is class Diplopoda
Centipedes (class Chilipoda)
Millipedes (class Diplopoda)
Explain class chilopod
centipedes have similar segments, 1 pair of legs per segment, first pair modified into maxillipeds with poison fangs
segments are somewhat flattened
fast-moving predators, live in moist places
explain class Diplopoda
millepedes have two pairs of short legs per segment: slow moving
millepede head bears a pair of each of antennae, mandibles, and maxillae
herbivores, perfer dark, moist places; protect themselves by curling up and secreting toxic fluids from repugnatiorial glands
what does this subphylum (crustacea) include terrestrial or aquatic arthropods
aquatic
what percentage of all named animal species are either crustaceans or insects
80%
explain the crustacean body plan, and what is unique
cephalothorax and segmented abdomen
one pair of appendages/per segments but highly modified to serve different functions
unique- are only arthropods with 2 pair of antennae
how does digestive system in crustaceans
crushing mandibles>esophagus>cardiac stomach>pyloric stomach>intestine
what type of development do crustacean have
most have indirect with true larval stage
what is the most primitive and widely occurring larvae among crustaceans
nauplius
What major group of
crustaceans includes,
crabs, lobsters, crayfish,
and how many species are
there in this group?
Order decapoda (about 18,000
species)
3 pairs of maxillipeds; five pairs
of walking legs, some have
major pincers (chelae)!
what is an example of terrestrial crustaceans
isopods (pillbugs)
lack a cuticle that prevents dehydration, so they must live in moist locations
what is an unusual crustacean and how is it classified as such
barnacles
sessile, filter feeders
they have jointed appendages, so they cant be molluscs
what is subphylum hexapoda body plan
head
thorax-3 pairs of legs on thorax
abdomen
have wings as adults
how important ecologically and to humans are subphylum hexapoda class insecta
all feeding types
inhibit all habitat except marine
important to humans bc of pollinators, crop and forest pests, disease vector
In terms of adaptive radiation and ecological success, which class in THE dominant terrestrial animal
insecta
1.1 mil species
how are insects so successful? (6 answers)
exoskeleton protects them from dehydration and serves
as a firm attachment for powerful muscles
efficient excretory system to conserve water
along with birds and bats, the only animals that can fly
larvae and adults avoid competition with each other
complex, effective internal respiratory system
Which type of flight muscles do
more primitive insects have
(such as grasshoppers and
dragonflies)?
direct flight muscles
how do direct flight muscles work
each wing stroke is initiated by
a nervous impulse- this is called
synchronous nervous control
explain indirect flight muscles
attached to thorax
asynchronous nervous control
=many wing strokes are
initiated by one nervous
impulse
makes possible very rapid wing
beats
e.g.true flies, gnats, and bees
