ch 26 outline: arthropods. what animals are in the phylum arthropods? a.bumble bees b.spiders...
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Ch 26 Outline: Arthropods
What animals are in the phylum Arthropods?
a. Bumble beesb. Spidersc. Octopusd. Lobsterse. Millepedes
Answer all that apply by holding up more than one card.
Answer: A, B, D, E
There are 3 Subphyla of Arthropods List the three subphyla that are
still living. If you can’t remember the names of the subphyla, write down the representative species that are in each group.
Answer: chelicerates, crustaceans, uniraminans
Which subphyla representatives are are matched to the proper names?
A. uniramians – prawns B. chelicerates – spiders C. crustaceans – cockroaches D. triobites – millepedes
4 Subphyla: Trilobites (now extinct) Chelicerates – spiders, ticks, mites,
scorpions, horseshoe crabs Crustaceans – crabs, shrimp,
lobster Uniramians – centipedes, bees,
moths, grasshoppers, flies, bettles
Evolution: Which insects have common ancestors with modern annelids (segmented worms)
A. insects B. Centipedes C. millipedes D. crustaceans E. spiders (chelicerates) (hold up multiple letters if more
than one answer apply)Answer: A, B, C
Evolution
Insects, centipedes and millipedes seem to have common ancestors with modern annelids
Crustaceans and spiders evolved from different ancestors
What is special about the Velvet worm?
A. it is a living fossil B. it is extinct, but has the characteristics of
arthropods C. It seems to be a “transition” organism
between the annelids and the arthropods D. It has larvae that are the same as insect
larvae E. It makes a substance that resembles
velvet
Answer: C
The Velvet worm Placed in its own
phylum (along with others like it)
Has characteristics of both annelids and arthropods
The First Arthropods?
What Evolutionary trends are shown within the Arthropods?
A. early arthropods have a sac body plan; later arthropods have tube-within-a-tube
B. early arthropods have bilateral symmetry; later arthropods have radial symmetry
C. early arthropods have many smaller body segments; later arthropods have fewer but larger body segments
D. early arthropods do not fly; later arthropods do E. early arthropods have many unspecialized
appendages, later arthropods have fewer, more specialized appendages
Answer: C and E
Arthropod Evolutionary Trends
Far fewer body segments (segments in embryo fuse into larger ones)
Appendages become more and more specialized
What are the names of the three main body segments of an insect?
A. head, legs, wings B. appendages, thorax, exoskeleton C. head, thorax, abdomen D. anterior, posterior, ventral E. dorsal, ventral, posterior
Answer: c
Structure – head, thorax and abdomen
List at least two characteristics that unify the phylum Arthropoda.
(Answer on next slide)
Arthropods – Characteristics that Unify
Jointed appendages– antennae,claws, legs, wings,flippers, etc.
Exoskeleton Segmented body Open circulatorysystems
What is the main molecule in exoskeletons, and what type of molecule is it?
A. cellulose, a complex carbohydrate B. glucose, a simple carbohydrate C. chitin, a complex carbohydrate D. starch a complex carbohydrate E. glycogen, a complex carbohydrate
Answer: C
What is a major DISADVANTAGE to having an exoskeleton rather than an endoskeleton?
A. it is not as strong as an endoskeleton B. it cannot heal like an endoskeleton can
(if it breaks) C. it is more vulnerable to breaking since it
is on the outside of the body D. it does not grow larger like an
endoskeleton can E. it is not as flexible as an endoskeleton is.
Answer: D
Exoskeletons Made of chitin Some
leathery/flexible Some waterproof Must be molted
for the animal to grow
There are 3 different structures that insects use to breathe. List at least 2 of them
(Answer on next slide)
Respiration
Arthropods have 3 basic structures for respiration:
Gills, book lungs and Tracheal tubes
Respiration - Arthropods
Aquatic arthropods (crabs and shrimp):
GILLS
Book Lungs – Layered Tissues
Unique to Chelicerates
Book lungs
How does the air come into the insect if it is “Breathing” using tracheal tubes?
A. the air moves through the tubes when the muscles move the abdominal cavity
B. there is an area inside the expands and contracts like our diaphragm – this draws the air in
C. they have an incurrent siphon that pulls the air through
D. they use their wings to “fan” the air in
Answer: A
What are “spiracles”? A. the sensory receptors on the ends of
antennae B. The structures that are used for hearing for
insects C. the structures that are used to spin webs in
spiders D. the holes that allow air into the tracheal
tubes E. the barbs on the sides of some insects legs
for extra traction.
Answer: D
Tracheal Tubes
Branching tubes throughout the tissues
Shrink and contract when insect’s muscles move
Causes air to pump in and out of tissues
Attached to spiracles (holes on outside of body)
Tracheal Tubes
Feeding
What can insects eat? A. plants B. animals C. rotting organic matter D. fungi (mushrooms) E. bacteria
Answer: ALL of the above!
Modified appendages enable different arthropods to eat almost anything
The Difference (s) between an open and closed circulatory system is (are):
a. Closed systems have a heart (pump); open systems do not.
b. Closed systems have blood vessels; open systems do not.
c. Closed systems do not have sinuses (pools of blood for nutrient exchange); open systems do.
d. Closed systems are more efficient at nutrient and gas exchange; open systems are less efficient.
e. Humans have closed circulatory systems; arthropods have open systemsAnswer: C, D , E
Internal Transport
OPEN circulatory system with a well-developed heart (limits their size!!)
Heart pumps blood through blood vessels to sinuses where gas and nutrient exchange occurs with the tissue
Blood re-collects in large cavity surrounding heart and then enters heart to be pumped again
Open vs. Closed Circulatory Systems
Open vs Closed Circulatory Systems
How do Arthropods get rid of their SOLID wastes?
A. the solid waste exits back through their mouths
B. The solid wastes exit through their anus C. The solid wastes exit through their
spiracles D. The solid wastes exit through their
Malpigian tubules E. The solid wastes exit through their
sinuses
Answer: B
How do Arthropods get rid of their nitrogenous wastes?
A. the N2 wastes are concentrated by their Malpigian tubules
B. the N2 wastes are excreted through their anus
C. the N2 wastes are excreted through their spiracles
D. The N2 wastes are concentrated by their tracheal tubes
E. The N2 wastes are excreted through their gills
Answer: A, B, E
Excretion Solid waste exits through anus
Insects and spiders remove nitrogenous wastes with Malpighian tubules that are in the blood sinuses
Nitrogenous wastes are concentrated by tubules and added to solid waste for excretion.
Where (in their bodies) do Arthropods have structures to get rid of nitrogenous waste
structures?
A. their head B. their abdomen C. the base of their legs D. their tracheal tubes E. the ends of their antennae
Answer: A, B, C
Some terrestrial arthropods may also have excretory glands on base of legs.
Some arthropod have these glands instead of Malpighian tubules
Aquatic Arthropod Excretion
Excrete metabolic wastes through gills.
Lobsters also have a pair of green glands on their head that eliminate nitrogenous wastes!
(green gland)
How are Arthropods’ nervous systems different than humans?
A. We have a brain, they only have ganglia B. Our brain controls all our body except for
reflexes; their brain controls some but not all of their functions
C. We have a nerve cord; they do not have a nerve cord
D. our nerve cord is on our dorsal surface; theirs is on their ventral surface
E. Our NS is higher functioning on all levels than their nervous systems
Answer: B, & D
Response –well developed NS
Have brains in head that act as main coordinator, and ganglia in each segment that coordinate movement in that segment.
Brain and ganglia are connected by a ventral nerve cord
How do compound eyes differ from Human eyes?
a. Compound eyes do not have the ability to focus an image as well as our eyes can
b. Compound eyes do not see colorc. Compound eyes can focus much better
than our eyes because they have SO many lenses to work with. Our eyes only have one lens.
d. Compound eyes see motion much better than our eyes can.
e. Compound eyes produce larger images than our eyes
Answer: A, D
Sense organs
Have simple organs – statocysts and chemoreceptors
Most also have more complicated organs
Compound eyes are common
> 2000 separate lenses – excellent at detecting colour and movement (better that we can!)
Most can detect UV light
Where do Arthropods have taste buds?
a. Tongueb. Mouth partsc. Legsd. Abdomene. antennae
Answer: B, C, E
Crustaceans and insects have a good sense of taste
“Taste-buds” located on mouthparts, legs and antenna
Also have hairs that detect motion very well
How are insect ears different than human ears?
a. Human ears can hear much higher frequencies than insect ears
b. Human ears hear much lower frequencies than insect ears
c. Human ears have “ear drums” that are inside the head and much more protected than the “ear drums” of insects.
d. Human ears are much better at detecting sound than insect ears
e. Human ears are not as good as insect ears at detecting sound at normal ranges.
Answer: C
Where are the “ear drums” (tympanic membranes) on a grasshopper?
a. On their headsb. On their thorax under their wingsc. On their abdomen behind their legsd. On their abdomen at the very ende. On their antennae
Answer: c
Many insects have ears that hear frequencies higher than we can
Eardrums are in different places – eg. Grasshopper have eardrums behind their legs
How do insects protect themselves from predators?
a. They sting or bite or pinchb. They are poisonousc. They can drop an appendage (sacrifice a
limb) and run awayd. They can camouflage themselvese. They mimic other animals that are
poisonous
Answer: All of the above!
Protection Exoskeleton and good NS help Some sting, some bite, some pinch,
some are poisonous Some crabs drop a claw that continues
to move while they escape Some have camouflage Some mimic other animals that are
poisonous
Bee Stinging
Camouflage
mandibles
Mimicry
Biting
Mimicry
How do insects move their bodies?
a. They use jet propulsion like octopi or squid. On land they use their spiracles and tracheal tubes to move air instead of water.
b. They have cilia that move them through the grass or the water
c. They swim in the water d. They use muscles to move their
exoskeletons similar to how humans use muscle to move their endoskeletons
e. They have special tissue that moves their exoskeleton from the outside.
Answer: D
Movement Move with
muscles coordinated by NS
Muscles use exoskeleton as we use our endoskeleton to move
What is the most common form of reproduction for arthropods?
a. External fertilizationb. Internal fertilizationc. Spore formationd. Egg productione. Internal development
Answer: B, D
Reproduction Most is internal
fertilization via special male organ
Spiders and some crustaceans leave a package of sperm for the female to pick up
How does an arthropod remove its exoskeleton when it needs to molt?
a. The exoskeleton will crack when the arthropod’s body becomes too large
b. The arthropods have a special internal appendage that can break open the endoskeleton from the inside.
c. The epidermal layer digests the inner exoskeleton layer to re-cycle the chitin
d. The arthropod must find a sharp object to scratch against to weaken the endoskeleton until it break through
Answer: C
Growing Requires MOLTING
Coordinated by hormones
1. The epidermal layer digests the inner exoskeleton layer to re-cycle the chitin
2. Arthropod body excretes a new exoskeleton (inside the old one)
3. Animal cracks the old exoskeleton and crawls out
4. May eat the old exoskeleton
5. Animal stretches the new exoskeleton to larger size (is done by pumping extra water into the body in aquatic arthropods)
New, larger exoskeleton will then harden
Grasshopper eating exoskeleton
Metamorphosis – A Drastic Change!
Insects demonstrate 2 forms of metamorphosis – complete and incomplete
Incomplete metamorphosis:
a. Insects enter the pupae stage but emerge without making the complete change in
Incomplete Metamorphosis
grasshoppers, mites, and crustaceans
the egg hatches into an immature animal that looks like the adult but lacks sex organs and other structures such as wings
Complete Metamorphosis Bees, moths,
beetles 4 stages:
1. Eggs
1. Eggs
2. Larvae – hatch from eggs. Look different from adult Grow bigger and molt several times.
Hang upside downIn “j” the day beforeIt turns into a pupa
3. Pupa – the last molt of a larva
Often has a protective coating
Body completely changes and rearranges. Old parts are digested to recycling the materials
just about ready to emerge
4. Adult – emerges from the pupal coccoon.
Even the animals behaviour will be different than the larval stage
Hormones, Molting and Metamorphosis
Molting hormone interacts with other hormones such as “juvenile” hormone
When juvenile hormone is high, the animal continues to molt into the larval stage. Each molt causes the animal to produce less hormone
At a critical lower level of juvenile hormone, the animal will molt into the pupa
When juvenile hormone is completely gone from the system, the pupa molts into the adult
Some plants use chemicals that mimic insect juvenile or molting hormone as a defence mechanism
Insecticides will also do this