ZOOLOGY PHYLUM ARTHROPODA
I.
Compared and Contrasted to Phylum
Annelida (the segmented worms)
A.
They are like annelids in that
1. They are eucoelomate animals that show
metamerism
a. Well-developed organ systems
2. Their nervous system is of the annelid plan
3. They have a complex muscular system capable
of
rapid contractions
4. They have a complete digestive system
B.
They are less complex than annelids in that
1. They have an open circulatory system
a. They still have a dorsal contractile heart
&
arteries
b. The coelom is reduced to a ____________
(the
main body cavity that contains the blood)
C. They are more complex than annelids in that
1. Their somites are more specialized for a
variety of purposes, forming
functional
groups called _______________________.
2. They have paired, jointed appendages
3. The soft cuticle of annelids has become a
hard _______________________
due
to the addition of _______________________ (a nitrogenous
polysaccharide)
and often calcium carbonate (especially in crustaceans).
a. This provides the muscles with something
resistant to pull on.
b. They no longer have a hydrostatic skeleton.
4. They have special mechanisms (gills, tracheae,
book lungs, tracheae) for
respiration
5. The sexes are separate
(_______________________)
a. Often show _______________________ (sharp
changes in form
during
postembryonic development)
6. They show a wider occurrence of social organization
II. Characteristics of Phylum Arthropoda
A. Arthropodization
1. The soft
cuticle of the ancestors of arthropods was stiffened by deposition of protein
and an inert polysaccharide, chitin.
2.
Joints had to provide flexibility and a sequence of _______________________
was
necessary to allow for growth.
3. The
hydrostatic skeleton function was lost, the coelom regressed and open
sinuses
replaced them.
B. Phylum
Arthropoda
1. This
contains over _______________________ of
all known species.
2. The
phylum has a rich fossil history dating to the late ___________________.
3.
Exoskeleton
a. The
primitive pattern is a linear series of similar somites with jointed
appendages.
b. Many
somites may be fused or combined into specialized groups called
tagmata.
c.
Appendages are often highly specialized for division of labor.
4. Sizes
range from the _______________________ (four meters in leg span) to the 0.1 mm
long _______________________.
5. Their
abundance and wide ecological distribution makes them the most
diverse
animal group.
6. All
modes of feeding occur among arthropods
a. Most are _______________________.
C. Classification of Phylum Arthropoda
1. Subphylum Trilobita
2. Subphylum Chelicerata
a. Class Merostomata
b. Class Arachnida (The coolest class of animals
on earth
at least
in Mrs. Estlacks humble opinion!)
c. Class Pycnogonida
3. Subphylum Crustacea (covered in Aquatic
Mandibulates)
4. Subphylum Uniramia (covered in Terrestrial
Mandibulates)
a. Class Diplopoda
b. Class Chilopoda
c. Class Pauropoda
d. Class Symphyla
e. Class Insecta
III. Why are arthropods so diverse and abundant
(in other words successful)?
A. The diversity of species, wide distribution,
variety of habitats and feeding habits, and
adaptations are
due to a constellation of structures and physiological patterns.
B. Versatile
Exoskeleton
1. The
_______________________ is highly protective but is jointed, providing
mobility.
2. The cuticle contains chitin bound with
protein.
3. Thus
the procuticle is lightweight, flexible, and provides protection against
dehydration.
4.
Impregnation with calcium salts makes the procuticle very hard in lobsters and
crabs.
5. The
cuticle is laminated and further hardened by ______________________,
a
chemical process.
6. As
the cuticle is thin between segments, it allows movement at the joints.
7.
_______________________, or molting, is the process of shedding its outer
covering
and growing a new, larger one.
8.
Arthropods typically molt _______________________ times.
a.
Each stage between the molts is called an ______________________.
b. The _______________________ of the
exoskeleton is a limit to
ultimate
body size.
C.
Segmentation and Appendages for Efficient Locomotion
1. Usually
each somite bears a pair of jointed appendages.
2.
Appendages may function in sensing, food handling, walking or
swimming.
D. Air Piped
Directly to Cells
1.
Terrestrial arthropods use an efficient _______________________ system
that
delivers oxygen directly to cells.
2.
Aquatic arthropods respire by various forms of efficient _________________.
E. Highly
Developed Sensory Organs
1. Eyes
vary from simple light sensitive ______________________
to a
______________________________________________.
2. Other
senses accomplish touch, smell, hearing, balancing and chemical
reception.
F. Complex
Behavior Patterns
1.
Arthropods surpass most other invertebrates in complex and organized
activities.
2. Most
behavior is _______________________ (or unlearned) but some is
learned.
G. Use of
Diverse Resources through Metamorphosis
1. Many
arthropods have metamorphic changes that result in different larval and
adult
stages.
2.
Larvae and adults eat different foods and occupy different habitat and thus
avoid _______________________.
IV. Subphylum Trilobita an ancient
group of arthropods
Trilobites arose before the Cambrian,
flourished, and then became extinct 200 million years ago.
A. They were bottom dwellers (benthic)
and probably were scavengers.
B. Ranging from 2 to 67 centimeters long, they
could roll up like pill bugs.
C. The body was divided into a head,
thorax and pygidium.
D. The head bore antennae, compound
eyes, a mouth, and jointed appendages.
E. Each body somite except the last bore
a pair of biramous appendages.
F. One of the
branches of the biramous appendage was fringed and may have been a gill.
1.
Arthropod appendages that are biramous have
two branches, an outer branch
and an inner branch. These branches
may have separate functions.
2. In crustaceans, for
instance, the inner branch of a leg is used for walking,
while the outer branch may be paddle-shaped or feathery and often
functions as
a gill.
V. Subphylum Chelicerata
A.
Characteristics
1.
Chelicerates have ______ pairs of appendages including
_______________________,
_______________________ and
______________________________________________.
2. They
lack _______________________ and
_______________________.
3. Most
suck liquid food from prey.
B. Class Merostomata: Subclass Eurypterida
1.
Eurypterids (giant water scorpions) were the largest of all fossil
arthropods at
three meters in length.
2. They
resemble both marine horseshoe crabs and terrestrial
scorpions.
3. It is widely accepted that life first evolved
in the ocean.
4. There is good evidence that eurypterids (or
an animal very like them)
were the first animal to emerge from the ocean
to colonize the
terrestrial
earth.
a.
Other arthropods emerged from the ocean and diversified.
b. They would be followed by a fish-like animal
that evolved into
todays
amphibians.
1) From these animals reptiles evolved.
a) From reptiles, birds and mammals evolved.
C.
Class Merostomata: Subclass Xiphosurida, Horseshoe Crabs
1. The modern horseshoe crab is nearly
unchanged from
ancestors
in the Triassic period. (living
fossils)
2. Five
species in three genera survive, mostly in shallow
marine
water.
Structures
a. An
unsegmented shield or carapace
covers the body in front of a broad abdomen and a telson.
b. The
cephalothorax has a pair of chelicerae (the most anterior head appendage that
has been modified among chelicerates to serve multiple purposes envenomation,
capturing prey, or eating prey), a pair of pedipalps, and four pairs of walking
legs pair of chelicerae.
c. The carapace has two compound and two
simple eyes.
4. They
walk with their walking legs and swim with abdominal plates.
5. They
feed at night on worms and small molluscs.
6. Reproduction
a.
During the mating season, they come to shore at a very high tide
to mate.
b.
Females burrow into sand to lay eggs; males follow to add sperm
before she covers the eggs.
c.
The young larvae hatch and return to the sea at the next very high tide.
d.
Larvae are segmented and resemble trilobites.
D. Class Pycnogonida: Sea Spiders
1. Sea
spiders vary from a few millimeters to larger sizes; all
have
small, thin bodies.
2. Sea
spiders occur in all oceans but are most common in polar
waters.
E. Class Arachnida
1. There
is a great diversity among scorpions, mites, ticks, daddy
longlegs
and others.
2. Most
are free living and more common in warm, dry regions.
3. Structures
a.
Arachnid bodies are divided into a cephalothorax and abdomen.
b.
The cephalothorax bears a pair of chelicerae, a pair of pedipalps and four
pairs of walking legs.
c. Antenna and mandibles are lacking.
d. Most are predaceous and have claws,
fangs, poison glands or stingers.
e. Sucking mouthparts ingest the fluids
and soft tissues from bodies of
their prey.
f. Spiders have spinning glands.
4. Over
70,000 species have been described.
5.
Scorpions appeared on land in the Silurian; mites and spiders were found by
the end
of the Paleozoic.
6. Most
are _______________________ to humans and provide essential
control
of injurious insects.
7. Some
spiders are venomous and can cause pain or death in humans; ticks
may
carry human diseases and mites can be crop pests.
VI. Phylum Arthropoda - Subphylum
Chelicerata Class Arachnida Order Araneae
THE
SPIDERS
A. About
_______________________ species of spiders are known.
1. The
body consists of an unsegmented cephalothorax and abdomen joined by
a slender
_______________________.
2. The
anterior appendages are a pair of chelicerae with terminal ____________.
3. A pair of
_______________________ has basal parts that help them handle
_______________________ and often
facilitates mating.
4. Four
pairs of walking legs terminate in _______________________.
B. All
spiders are predaceous, mostly on _______________________, which are
dispatched by
poison and fangs.
1. The
injected venom liquefies and digests the tissues; this is sucked into the
spiders
stomach.
C. Spiders
breathe by _______________________and/or tracheae.
1. Book
lungs are unique to spiders; parallel air pockets extend into a blood-filled
chamber.
2. Air enters
the chamber through a slit in the body wall.
D. Spiders
and insects have _______________________ for an excretory system.
1.
Potassium, other solutes and waste molecules are secreted into the tubules.
2.
Rectal glands reabsorb the potassium and water, leaving wastes and uric acid
for
excretion.
3. This
conserves _______________________ and allows the organisms to live
in dry
environments.
E. Sensory
Systems
1. Most
spiders have _______________________ eyes, each with a lens, optic
rods and
a retina.
2. They
detect movement and may form images.
3. Sensory
_______________________ detect air currents, web vibrations and
other
stimuli.
F.
Web-Spinning Habits
1.
Spinning _______________________ is a critical ability for spiders and some
other
arachnids.
2. Two
or three pairs of _______________________ contain microscopic tubes
that run
to silk glands.
3. A
liquid scleroprotein secretion hardens as it is extruded from the spinnerets.
4. Silk
threads are very strong and will stretch considerably before breaking.
5. Silk
is used for orb webs, lining burrows, forming egg sacs and wrapping prey.
G.
Reproduction
1.
Before mating, the male stores his sperm in his _______________________.
2. Mating
involves inserting the pedipalps into the female genital openings.
3. A
courtship ritual is often required before the female will allow mating.
4. Eggs
may develop in a cocoon in the web or may be carried by the female.
5. The
young hatch in about two weeks and may molt before leaving the egg
cocoon.
Watch this video of jumping spiders
courting! https://youtu.be/z-tXJmXQ6Is
OK
this is a funny edit of mating
behavior: http://youtu.be/sde06NqYi9A
H. Are
spiders really dangerous?
1. Most
fear spiders without good reason.
2. Spiders
are allies of humans in our battle with _______________________.
3.
American tarantulas rarely bite and the bite is not dangerous.
4. Below
is a map (Discover 2005) of the
distribution of dangerous spider species
in the
U.S.
|
|
Yellow sac spider throughout USA Black Widow throughout USA Hobo spider Brown
Recluse - Loxosceles
recluse Other brown recluse species |
I. Species of black widow spiders (____________________________________ ) are dangerous. They are distributed worldwide. There are 3 species in the U.S.
A.
They are called black widows because it was believed they always ate
their mate (the male).
1. They do in captivity. This occurs rarely in nature,
only
when the female is very hungry.
B.
The venom is _______________________.
1. Some people are slightly affected by the
venom,
while others may have a severe response.
a.
Rarely fatal only small children and the
elderly are typically at risk of
death.
2. The first (typical) symptom is acute pain at
the site of
the bite
3. The local pain may be followed by localized
or
generalized
severe muscle cramps, abdominal pain,
weakness,
and tremor. In severe cases, nausea,
vomiting,
faintness, dizziness, chest pain, and
respiratory
difficulties may follow.
4. Symptoms often diminish after a day or so and
cease
after several days.
J. The brown
recluse (____________________________)
spider has _______________________ venom that
destroys
tissue around the bite.
1. The
venom is extremely poisonous, even more
potent
than that of a _______________________.
2. Recluse venom causes less disease than a
rattlesnake
bite because of the small quantities
injected
into its victims.
3. This venom is a collection of enzymes that
causes
destruction of local cell membranes, leading
to local
breakdown of skin, fat, and blood
vessels.
a.
This process leads to eventual tissue
death called _______________________ in areas
immediately surrounding the bite site.
b.
Bites
often go unnoticed initially because they are usually
_______________________bites.
c.
Many brown recluse bites cause just a little
red mark that heals without event.
1)
The
vast majority of brown recluse bites
heal without severe scarring.
4. Symptoms usually develop 2-8 hours after a
bite and
can include
a. Severe pain & itching at bite site
b. Nausea, vomiting, and fever
c. Myalgias (muscle pain)
5. Initially the bite site is mildly red; the
redness gives way to pallor with a red
ring
surrounding the area, or a "bull's-eye" appearance.
6. The center area will then often
_______________________, which over 12-
48 hours
can sink, turning bluish then _______________________ as this area
of
tissue dies.
7. This can leave a deep, infected wound that
enlarges, fails to heal, or heals
slowly
over 6 to 8 weeks, often leaving scarring behind.
8. Treatment for severe bites includes both
_______________________ (to stop
the
immune response) and _______________________ (to combat infection of
the
wound)
K. Black widows and brown recluses are the only native US spiders that are
dangerous.
1.
Some Australian and South American spiders are
the most dangerous and
aggressive.
2. There are two introduced spiders that are
dangerous and are becoming more
common
in the U.S.
a.
The yellow (golden) sac spiders (Cheiracanthium
mildei)
b.
9) The hobo spider, Tegenaria agrestis
L. Yellow (golden) sac
spiders (Cheiracanthium mildei)
1. How it was introduced:
accidentally shipped to US in agricultural products, especially grapes.
2. Where it is found:
well-established in California, the Pacific Northwest, and southeastern
Idaho.
a. Because they were shipped with grapes, they
are
probably distributed
throughout the USA.
3. Bites: more
aggressive than native venomous spiders.
They are very prone
to bite defensively
a. It is likely that many
arachnidism ascribed to the brown recluse
spider
outside of its natural range, are actually
yellow
sac spider bites.
b. Bites generally produce instant, intense
stinging
pain, not unlike that of the sting of a
wasp or
hornet.
c. May be followed by localized redness,
swelling and itching; these manifestations may or may not evolve into a
necrotic lesion, but when that occurs healing is usually complete within eight
weeks.
d. Systemic effects are usually not
severe, but when they occur may include chills, fever, headache, dizziness, nausea,
anorexia, and sometimes shock.
M. The
hobo spider, Tegenaria agrestis
1. How it was introduced:
Accidentally shipped from western Europe as egg sacs in commercial
shipping vessels to Port of Seattle sometime before the 1930s.
2. Where it is found: By 1968 it had become established as far
east as Spokane, Washington and Moscow, Idaho, and as far south as Corvallis,
Oregon.
a. The hobo spider is now the leading cause
of
serious envenomation in the northwestern
United
States.
3. Bites: Typically, defensive bites by the hobo
spider
are lightning fast, then the animal withdraws
rapidly. Very often the bite itself is painless.
a.
Local effects are almost identical to those produced by brown recluse
spider.
b.
Systemic, or generalized effects are seen in about 45% of persons envenomated by hobo spiders.
c.
The most common reported symptom is severe headache, which
usually does not respond to over the
counter analgesics.
d.
Victims may experience a dry mouth, nausea, weakness and lethargy,
dizziness, visual disturbances,
hallucinations, joint pain and/or other
undesirable effects.
e.
About 15% of envenomated subjects are poisoned severely enough to
require hospitalization.
1. In rare cases aplastic anemia (bone
marrow failure) can
develop
several weeks after the bite, which results in a fatal
outcome.
VII. Phylum Arthropoda - Subphylum
Chelicerata Class Arachnida Order Scorpionida
A. Scorpions are more common in tropical and subtropical
zones but do occur in
temperate
areas.
B. They are
_______________________ and feed largely on insects and spiders.
C.
Sand-dwelling scorpions locate prey by detecting surface waves with their leg
_______________________.
D. The
cephalothorax has the appendages, a pair of medial eyes and 2-5 lateral eyes.
E. The
_______________________ has seven segments.
F. The
_______________________ has five, long, slender segments that end in a
telson.
1. We call the _______________________ the tail.
2. We call the _______________________ the
stinger.
G. Under the
abdomen are comblike _______________________ that explore the
ground and
help in sex recognition.
H. The
stinger on the last segment has venom that varies from mildly painful to
dangerous.
I. Scorpions
perform a mating dance where the male guides the female over the
_______________________ (a structure that stores his sperm and
that he has attached
to the
substrate before mating).
1. Watch this! http://youtu.be/UX-jk1H2aDM
J. Scorpions
are ovoviviparous or viviparous and produce from six to 90 young.
K. Of the many species of scorpions in the
United States, only one is considered to be
life-threatening.
This is the bark scorpion, Centruroides sculpturatus (actually a
synonym of C.
exilicauda) found in the Sonoran desert of Arizona.
1. The
venom causes a stinging or burning sensation at the injection site, often
with very little swelling or
inflammation, but always with a positive "tap test" (i.e.,
extreme pain when the sting site is
tapped with a finger).
2. Systemic reactions include progressive
hyperactivity (restlessness)
progressing
to convulsions, "roving eyes," ataxia (staggering gait), thick tongue
sensation,
slurred speech, drooling, hyperesthesia (excessive sensitivity of skin),
muscle
fasciculations (twitches), abdominal pain and cramps, and respiratory
depression.
3. These symptoms usually subside within 48
hours.
4. Systemic reactions to scorpion stings (even
to the sting of the bark scorpion) are rare.
VIII. Phylum Arthropoda - Subphylum
Chelicerata Class Arachnida Order Opiliones
|
|
A.
Order Opiliones: Harvestmen 1. Harvestmen or daddy longlegs are
common, particularly in tropical regions. 2. Unlike spiders, their abdomen and
cephalothorax join broadly without a narrow pedicel. 3. They can lose most of their eight
long legs without ill effect. 4.
They often congregate in large groups. 5. Their chelicerae are pincerlike and
they feed more as scavengers than do spiders. a) Myth:
Their venom is extremely toxic to humans. b) Their venom isnt extremely toxic. c) Their fangs are too short to puncture human
skin. |
|
IX. Phylum Arthropoda - Subphylum
Chelicerata Class Arachnida Order Acari
A. Order Acari: Ticks and Mites
a. Acari
are medically and economically the most important arachnids.
b. About
30,000 species have been described, many more are estimated to exist.
c. They
are both aquatic and terrestrial, and inhabit deserts, polar areas and hot
springs.
d. Most
mites are less than 1 millimeter long;
ticks may range up to 2 cm.
e.
Acarines have complete fusion of cephalothorax and abdomen with no sign of
external
segmentation.
f. House dust mites are free-living and
often cause allergies.
g. Spider mites are one of many important
agricultural pest mites that suck out
plant
nutrients.
h. Chiggers are larval Trombicula mites;
they feed on dermal tissues and cause
skin
irritation.
i. The
hair follicle mite Demodex is harmless but other species cause mange in
domestic
animals.
j. Tick
species of Ixodes carry Lyme
disease.
k. Tick
species of Dermacentor transmit Rocky
Mountain spotted fever.
l. The cattle tick transmits Texas cattle fever.