Transcript Arthropod Powerpoint

Animal Kingdom
Phylum Arthropoda
Chp 26
Why are there so many
arthropods?




Appeared more than 600mya
Started in water then moved to land
First body form is similar to the trilobitethick outer covering, many segments, pair
of appendages
Most today have fewer body segments and
the appendages are specialized for feeding
or movement
Key Features






Tough Exoskeleton
Series of jointed appendages
Segmented body
Brain at dorsal part of the head
Ventral nerve cord
Open circulatory system with single heart
Body Plan -Exoskeleton




Exoskeleton made of a carb called chitin.
Some are very hard or flexible
Keeps water inside
Protects against damage
Appendages



Jointed appendages (arthro-joint, pod-foot)
Antennae, claws, walking legs, wings,
flippers are all appendages
All have segmented bodies as well
Feeding





Varies
Herbivores (locusts)
Carnivores (spiders)
Parasites (ticks)
Filter feeders (marine)
Respiration




Gills (crabs and shrimp) –small feather-like
structures under the exoskeleton
Book gills (horseshoe crabs)-layers of tissues for
gas exchange –beneath the body
Book lungs (spiders and kin)-contained in a sac
in the body and connect to a spiracle –opening
Tracheal tubes-tubes that extend into the body
(as they move they shrink and expand air)-very
small animals.
Internal Transport



Heart pumps blood into an opencirculatory system (blood does not always
travel in blood vessels)
Blood moves from arteries to smaller
vessels to tissues and then collects in
sinuses (spaces within tissue)
Collects in a cavity around the heart and reenters the heart
Excretion



Solid waste containing Nitrogen
Through Malphigian tubules they remove
waste from blood and transport through the
anus.
Aquatic organisms release wastes through
gills
Response







Most have a well developed nervous system
Brain with ganglia in the head
Pair of ganglia at each segment
Compound eyes- more complex than human
Taste with mouthparts, antennae, legs
Hear above human sounds- but ears are in odd
places
Escape from predators by using venom, drop a
claw or leg, or use camouflage
Movement & Reproduction


Coordinated muscle system with
exoskeleton
Usually male & female produce sperm &
egg cells and fertilization is within the
female
Growth and Development




To grow arthropods must molt and shed
the exoskeleton
Hide from predators during this process
Some perform a metamorphosis- and
dramatically change form
Incomplete metamorphosis- gradual
change and the young(nymph) look very
similar to the adult (grasshopper)
Complete Metamorphosis



Eggs hatch into larvae
Grow and molt and form a pupa
(protective covering and grow adult
structures)
Decreasing levels of juvenile hormone
advance it to the next stage
Insects





Head, thorax, and abdomen
3 pairs of legs attached to the thorax
Pair of antennae, eyes, 2 pair of wings, and
tracheal tubes
Feeding-3 pair of appendages that are
mouth parts, and use mandibles (vary
among each insect)
Some secrete enzymes to digest food
Movement





3 pairs of legs with spines and hooks to
hold on
Jumping
Capturing and holding prey
Flying varies
Many mitochondria for energy
Insect Societies






Social insects live in societies
There is a division of labor
There are several castes- types
Reproductive females(queens)
Reproductive males (stay with queen)
Workers perform all other tasks
Insect Communication
Sound, visual, chemical signals
 Pheremones are chemical messangers
 Can be used when food was found, death of a
member, alarm for danger
 Round dance-source of food within 50m
more changes in direction-better quality
Waggle Dance-food is more than 50m away(longer
the dance, farther away)
direction of dance indicates direction of food

Why are Arthropods important?






Food source for many carnivores
Plants need them for pollination
Agriculture would not be possible
Honey and silk
Food source for people
Useful chemicals-purity of meds, surgical
thread and stitches