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Biology II
Arthropod
Study Guide
1. List the 4 subphyla in the phylum arthropoda and what types of animals are in
each.
1. Trilobita: oldest; trilobites dwellers of the ancient seas
-all extinct
2. Chelicerata: includes spiders, ticks, mites, scorpions,
and horseshoe crabs
3. Crustacea: include crabs and shrimp
4. Uniramians: centipedes, millipedes, and all insects
2. What are the 3 most important features arthropods have in common?
3 most important are tough exoskeleton, series of jointed
appendages, and segmented body
3. Describe the exoskeleton.
exoskeleton: external supporting structures made primarily of
The protein chitin
-often waterproof and helps prevent water loss
-can’t grow as animal grows
-movement at joints only
4. Describe the 3 main types of respiratory structures and what types of animals use
each one.
1. Gills--many aquatic arthropods such as crabs and shrimp
-movement of mouthparts and appendages keeps water
moving over gills
2. Book Lungs--spiders and their relatives
-several sheets of tissue layered like pages in a book
-layers increase surface area for gas exchange
-connected to outside through hole in exoskeleton called a
spiracle3. Tracheal Tubes--insects, some spiders, and millipedes
-from spiracles long branching tracheal tubes reach deep
into animal’s tissues
-network of tubes supplies oxygen by diffusion to
all body tissues
-as animals walk, fly, or crawl body muscles cause tracheae
to shrink and expand pumping air in and out
-only work for small animals; not efficient enough
for larger animals
5. What type of circulatory system do arthropods have?
well-developed heart pumps blood through open circulatory
System
6. What are malpighian tubules and how do they work?
most terrestrial arthropods use malpighian tubules
-tubules bathed in blood and remove waste from blood,
concentrates them, and then adds them to undigested
food before it leaves
7. Describe 2 other ways cellular waste products are eliminated in some arthropods.
- arthropods eliminate wastes into water through
unarmored places in exoskeleton such as gills
-others also eliminate wastes through pair of green glands
located near base of antennae
-these wastes emptied outside body through pair of
appendages on head
8. Describe the nervous system of arthropods.
-most have well-developed nervous system
-all have a brain that consists of a pair of ganlia in head—serve
As central switchboards for incoming and outgoing info
-from brain pair of nerves run around esophagus and connects
Brain to nerve cord that runs along ventral part of body
-several more ganglia along nerve cord
-serve as local command centers to coordinate movement of legs
and wings—can still move after head removed-have simple sense organs such as
statocysts and chemical receptors
-most have sophisticated sense organs such as compound eyes-crustaceans and insects
have well-developed sense of taste
-crustaceans and insects have sensory hairs that detect movement
In water or air
-located on antennae,body, and legs
9. Why are some arthropods able to move around after the head is removed?
-several more ganglia along nerve cord
-serve as local command centers to coordinate movement of legs
and wings—can still move after head removed
10. What are compound eyes good at detecting?
-may have more than 2000 separate lenses and can detect
color and motion
11. Where are the eardrums of grasshoppers located?
eardrums in grasshoppers located behind legs
12. Where are the sensory hairs of crustaceans and insects located and what do they
detect?
-crustaceans and insects have sensory hairs that detect movement
In water or air
-located on antennae,body, and legs
13. Describe how arthropods evade predators.
some have venomous stings such as scorpions,bees, and some
ants
-lobsters and crabs can attack enemies with powerful claws
-many insects and millipedes fight back with nasty chemicals
-some create diversions by dropping a claw or leg that eventually
Grows back
-some use visual trickery
- camouflage and mimicry--imitating a dangerous animal
14. What do muscles pull against to produce movement?
-muscles pull against exoskeleton to produce movement
15. What type of fertilization do most arthropods have?
males and females produce gametes and fertilization usually takes place
Inside the female’s body
16. How does fertilization take place in some spiders and crustaceans?
in some Spiders and crustaceans male deposits small
Packet of sperm that female picks up
17. Describe the molting process of arthropods.
in order to grow all arthropods must molt or shed exoskeleton
-controlled by several hormones especially the
molting hormone
-when molting time is near the epidermis digests the inner
layer of the exoskeleton and absorbs most of the chitin in
order to recycle the chemicals
after new exoskeleton is secreted inside the old one the arthropod
pulls completely out of the old exoskeleton
-then expands to larger size and new exoskeleton hardens
-can take a few hours to a few days to completely
harden
18. Describe incomplete metamorphosis.
Incomplete metamorphosis—eggs hatch into young that look like
mini-adults
-often lack functioning sexual organs and other
adult structures such as wings
-as young grow they keep molting resembling adult
more each time until adult size reached
-egg, nymph, and adult
-ex. grasshoppers, mites, and crustaceans
19. Describe complete metamorphosis.
Complete metamorphosis—eggs hatch into larva that look
nothing like the adult
-as larvae grow they molt several times but change
little in appearance
-when larvae reach certain age it sheds its larval skin one
last time and becomes a pupa
-insect’s body totally rearranged
-adult structures grow from tiny buds and larval
structures broken down to supply raw materials
for adult structures
-when metamorphosis complete adult emerges
-larva and pupa totally different from
adult
-egg,larva, pupa, and adult
-ex. Many insects such as bees, moths,
and beetles
20. Explain how juvenile hormone helps control the process of complete
metamorphosis.
Metamorphosis controlled by hormones including molting
hormone
-for complete metamorphosis levels of juvenile hormone
help regulate stages of development
-high levels of juvenile hormone keep an insect in its larval
form with each molting
-as insect matures level of juvenile hormone decreases
-when juvenile hormone drops below critical level insect becomes
pupa next time it molts
-when no juvenile hormone produced insect undergoes pupa
to adult molt
21. What types of animals are in the subphylum chelicerata?
subphylum Chelicerata--horseshoe crabs, ticks, mites, spiders,
And scorpions for ex.
22. What are the 2 body segments of these animals called and what is contained in
each?
have cephalothorax--contains brain, eyes, mouth, and
Mouthparts, esophagus, several pairs of walking legs, and front part of
Digestive tract
-Abdomen contains most of internal organs
23. What do these animals lack that most other arthropods have?
lack sensory “feelers” found on heads of most arthropods
24. What are the 2 pairs of appendages adapted as mouthparts called?
have 2 pairs of appendages attached near mouth adapted as
Mouthparts
-1st pair called chelicerae
-2nd pair called pedipalps--longer
25. Briefly describe horseshoe crabs.
Horseshoe Crabs—Class Merostomata
-have 5 pairs of walking legs and long spikelike tails
-can grow up to 60 cm long
26. What animals are included in the arachnids?
include spiders, scorpions, ticks, and mites
27. What characteristics do all arachnids share?
-all have 4 pairs of walking legs on cephalothorax
28. How are the chelicerae of spiders used to catch and eat prey?
use hollow fanglike chelicerae to inject paralyzing
venom
-then introduce enzymes through wounds that break
down tissues and then suck out liquefied tissues
29. What substance is produced by all spiders and what organs produce it?
all produce strong flexible protein called silk
-5 times stronger than steel
-produced in organs called spinnerets
30. Most mites and ticks are what?
parasites
31. Describe the chelicerae and pedipalps of these animals.
in many, chelicerae are needlelike structures used
to pierce skin of host
-may also have large teeth to help them hang
on
-pedipalps often equipped with claws for
digging in and holding on
32. What 2 diseases are ticks known to spread?
ticks can spread Rocky Mountain Spotted Fever and
Lyme Disease
33. How do scorpions get their food?
Carnivores that feed on other invertebrates
34. Describe the chelicerae and pedipalps of scorpions.
Pedipalps usually enlarged into pair of clawschews prey with chelicerae
35. Where is the venomous barb of scorpions located?
abdomen long and segmented has a venomous
barb on end used to sting prey
36. How many body segments do insects have and what are they called?
characterized by body divided into 3 segments—
head, thorax, and abdomen
37. What are some methods insects use to communicate?
some produce chemicals to communicate with others in
their species called pheromones
-some use vocalizations for communication, bees use
dances, along with chemicals and touch
38. Which body segment are the legs attached to and how many legs do they have?
Have 3 pairs of legs located on the thorax
39. What organs do insects use for respiration?
use tracheal tubes for respiration
40. What animals are included in the crustaceans and which is the only land
crustacean?
Crustaceans—crabs, lobsters, shrimp, crayfish, barnacles, water
fleas, pill bugs
-only land crustaceans are pill bugs—rolie polies
41. What is unique about the crustaceans amongst the arthropods?
only arthropods with 2 pairs of antennae for sensing
42. What are some other characteristics most crustaceans have in common?
all have mandibles for crushing food, 2 compound eyes usually on stalks
-many have 4 pairs of walking legs
-1st pair often modified into claws for defense
43. How many body sections would you expect crustaceans to have?
some have 3 body sections and some only have 2
44. What animals are in the class Chilipoda?
centipedes
45. What animals are in the class Diplopoda?
millipedes
46. Compare and contrast these two groups of animals.
-Class Chilipoda--centipedes
-carnivorous and eat arthropods, snails, and worms
-bites painful to humans
-1 pair of legs per segment
-Class Diplipoda--millipedes
-eat mostly plants and dead material on forest floor
-don’t bite, but can spray smelly fluid
-2 pairs of legs per segment
-both have malpighian tubules for excretion
-both use book lungs for respiration instead of
tracheal tubes
47. What portion of the world’s plants rely on insects for pollination?
2/3
48. List some ways arthropods benefit and hurt us.
some are parasites
-bees produce honey, silkworms produce silk
-extract of horseshoe blood used to check purity of medications
-chitin used to dress wounds and make thread for surgical stitches
49. Which group of arthropods is the most numerous?
Insects