Ch 18: Arthropoda Intro Flashcards
5 subgroups/phyla
- crustaceans
- trilobites
- chelicerata
- myriapods
- hexapods
6 body features
- segmented body, some fused
- hardened chitinous exoskeleton
- jointed appendages, specialized
- well-cephalized w/ well-developed sensory organs
- no motile cilia on cells
- striated muscles
3 functs of exoskeleton
- defense
- muscle attachment
- water-proofing
7 funct of appendages
- walking/jumping
- swimming
- prey capture and defense
- feeding
- olfaction
- tactile
- copulation
muscles (2)
- highly innervated for fast response
- a single neuron may innervate many fibers
4 reasons for arthropod success
- adaptability of body plan
- small size
- rapid generation time
- innovations like flight and silk
adaptability of body plan
- body regions and appendages can be specialized
- waterproof ability
small size adv (2)
- many open niches
- don’t need many resources to survive
rapid generation time allows (2)
- rapid exploitation of new habitats
- evolution can occur quickly
4 benefits to flight
- more food sources
- better access to mates
- more efficient dispersal
- escape predators
5 features of the exoskeleton/cuticle
- non-living
- makes up most external structures
- carries internal ridges for muscle attachment
- a series of plates connected by areas of thin cuticle and a rubbery protein called resilin
- layered
3 layers of the exoskeleton
- outermost
- thin
- waxy
endo and exocuticle contain (3)
- chitin
- proteins
- CaCO3 in crustaceans
sclerotized
darker, harder, more chitin and sclerotin
molting allows for (3)
- growth
- repair
- metamorphosis
which cuticle get recycled during metamorphosis?
endocuticle
which cells create new layers
epithelial
ecdysis
old epi and exocuticle break along ecdysal lines and shed
ecdysal lines
non-sclerotized weak points
exuvia
old epi and exocuticle
how does ecdysis begin
expanding body via air, w, w/ specialized muscles
what must the outer layer do after molting
sclerotize
what is molting controlled by
hormones
3 things that can stimulate molting
- temp
- day length
- feeding/stretch receptors
5 steps to molt
- stimulus
- impulses reach brain
- neurosensory cells prod neurohormones
- molting glands stimulated prod molting hormone
- epidermis and other target cells affected
high levels of JH
molt to another juvi
low lvls of JH
molt to pupa/adult
3 feat of tagmata
- made of several ancestral segments
- ancestral appendages may be retained or modified
- tagmata specialized
3 tagmata in insects
- head
- thorax
- abdomen
tagmata in myriapods (2)
- head
- trunk
2 tagmata in crustaceans
- cephalothorax
- abdomen
2 tagmata in spiders
- cephalothorax
- abdomen
head funct
eating, gathering sensory info
5 types of appendages that can be on the head
- mandibles
- antennae
- maxillae
- chelicerae
- pedipalps
types of eyes
ocelli, compound
3 feat of the thorax
- carries walking appendages
- carries wings
- muscular
2 feat of abdomen
- contains viscera
- muscles for swimming, digging
nervous system (2)
- anterior brain connects to a subesophageal ganglion
- pair of ventral nerve cords w/ segmental ganglia and multiple nerve strands
circ open or closed?
open
3 feat circ
- dorsal heart pumps hemolymph anteriorly
- holes along heart sides (ostia)
- hemolymph flows back thru hemocoel
4 hemolymph funct
- hydraulic pres
- transport and storage
- protection
- temp regulation
do insects use their hemolynph to transport/store O2 and CO2?
no
aquatic spp have
gills
terrestrial spp have (2)
trachea or book lungs
the tracheal system is
an internal duct system
the tracheal ducts are lined by
cuticle
spiracles
openings to outside from the tracheal ducts
what do the tracheae open into
air sacs
air movement in the tracheal ducts in incd by
abdominal pumping
book lungs are present in
spiders
book lungs are a
moist internal space for gas exchange into hemolymph w/ layered circ system extensions
gut
one way
cuticular teeth
for mechanical digestion partway down
aquatic spp excrete
NH3 - needs to be diluted, which requires lots of w
insects/myriapods excrete
uric acid, costs little w but costs C and E
arachnids excrete
guanine
malpighian tubules (3)
- empty into the intestines
- filter the hemolymph
- excrete into the hind gut
insect frass
nitrogenous wastes and feces
