Phylum Arthropoda joint foot 80% of all animals are
arthropods.. 76% of those are insects..
Slide 2
Major Classes of Arthropods Above left: Class Chilipoda :
includes the centipedes Lower Right: Class Insecta : includes all 6
legged insects Above:, Class Diplopoda : includes the
millipedes
Slide 3
Above Class Arachnida : includes the spiders, mites and
scorpions Above Class Malacostraca : includes the lobsters, crab
and shrimp
Slide 4
Features Jointed appendages segmented Coelomate and bilaterally
symmetrical Exoskeleton of made of chitin secreted by the epidermis
Open circulatory system Respiration by body surface, gills,
trachea, or book lungs Sensory organs are well-developed: compound
eyes, tympanum (drum-like ear) antenna (touch, smell, chemical
reception) Developed nervous system with dorsal brain connected by
a ring and double ventral nerve cords Dioecious: fertilization is
usually internal
Slide 5
Growth and Development molt- shedding previous exoskeleton for
a new one in order to grow metamorphosis- changes that the
arthropods undergo as they develop from a larva to an adult
grasshoppers undergo incomplete metamorphosis, when they hatch they
resemble the adult form Butterflies undergo complete metamorphosis
in which the hatched egg looks completely different then the adult
butterfly
Slide 6
Obtaining Nutrients carnivores- feed on dead animals and prey
on exoskeleton animals ( ex: spiders ) herbivores- some fed on
particular plants only others feed on various types of greenery
parasites- blood or body fluids of host(ticks) filter feeders-
marine arthropods detritus feeders- decayed plants and animals
Slide 7
Feeding Digestive tract with two openings (one- way digestion)
Mouthparts of individual species are highly specialized for a
particular food type e.g. Australian Bulldog Ant (or bullant) it s
diet includes small insects, seeds, fruit, and fungi
Slide 8
Respiration Specialized organs for gas exchange Aquatic species
have gills Terrestrial species have tracheal systems
Slide 9
Respiration in Aquatic Species Aquatic species have gills
formed from the appendages that form mouth and legs, water
continuously travels through Some aquatic species (horseshoe crab)
have book gills Leaf-like layered tissue that increases the surface
area of gas exchange and have blood vessels
Slide 10
Respiration in Terrestrial Species Terrestrial species have
tracheal system openings called spiracles lead to a network of
tubes called tracheal tubes which run throughout the body the
movement of the animal causes the rhythmic pumping that allows air
to enter through the spiracles and into the tracheal tubes
Slide 11
Movement Well developed groups of muscles are controlled by the
nervous system. Muscle cells are attached to the exoskeleton in
order to generate force.
Slide 12
Reproduction Sexual reproduction and all members are separate
sexed Terrestrial species have internal fertilization. In some
species, males have organs which place the sperm inside the females
while others deposit a sperm packet that is picked up by the
female. Aquatic species can have either internal or external
fertilization where eggs and sperm are broadcast into the
surrounding waters.
Slide 13
Class Chilopoda The Centipedes About 30-35pairs of legs Very
annelid-like with repeating segments Setae are modified to crude
appendages - only specialized in the mouthparts Centipedes are
carnivores with venomous mouthparts and feed on earthworms, toads,
snakes, and mice
Slide 14
Class Diplopoda The Millipedes Very annelid like but have an
exoskeleton No antennae Millipedes are herbivores and may defend
themselves by secreting unpleasant or toxic chemicals
Slide 15
Subphylum Crustacea E.g. crabs, shrimps, lobsters, &
crayfishes, 2 pairs of antennae (typically) & chewing
mouthparts called mandibles 2 or 3 body sections: head, thorax, and
abdomen (often the head and thorax are fused into one section
called a cephalothorax ) this section is protected by a part of the
exoskeleton called the carapace Respiration occurs through
structures called gills
Slide 16
Class Arachnidia Includes spiders, scorpions, ticks 2 body
sections cephalothorax & abdomen 4 pairs of walking legs (most)
Mouthparts called chelicerae contain fangs stab & paralyze prey
Mouthparts called pedipalps are used to grab prey Lack antennae
Spiders all produce silk in organs called spinnerets All are
predators or parasties
Slide 17
Class Insecta Compose about 80% of the animal kingdom Have
three separate body regions and three pairs of legs Only
invertebrate capable of flight Respiration with tracheids,
excretion by Malpighian Tubules
Slide 18
Circulation A well developed heart pumps blood through an open
circulatory system. The body cavity that contains the blood is
called the hemocoel In an open circulatory system, blood is NOT
always contained in vessels but will pool in spaces called sinuses
to bathe organs in blood.
Slide 19
Excretion Most have specialized structures called Malpighian
tubules. These remove metabolic wastes from the blood, concentrate
the waste into uric acid, and add them to the feces in the
intestine before elimination.
Slide 20
Response All have a brain consisting of 2 ganglia which
connects to a nerve cord which runs the length of the body. Well
developed sensory organs many have compound eyes and well developed
chemoreceptors (smell/taste) E.g. dragonfly
Slide 21
Why are the insects so successful?? 1. Size: tiny to minute -
dont eat much, can hide 2. Exoskeleton: hard, yet great strength 3.
Short life span - dont eat much 4. Reproduction: all sexual -
variation 5. Flight: many advantages 6. Specialized appendages: eat
many things 7. Adaption of exoskeleton: camouflage etc 8. Well
developed sensory ability 9. Evolved social behavior 10. Very
specific niches: minimizes competition
Slide 22
Slide 23
Ecological Roles of Arthropods Pollination Production of honey,
wax, and silk Recycle biological materials to aid in producing
topsoil Form symbiotic relationships with other organisms (see
left) Part of food chain Burrowing shrimp and Goby fish living in
Symbiosis shrimp cleans and digs a burrow where they both live
(shrimp is blind) When danger approaches, the goby fish touches the
shrimp with its tail to warn it and both hide in the burrow
Slide 24
Continued insects help pollinate crops ( example: bees
pollinate flowers ) some insects destroy other harmful insects (
Ex: ladybird beetles eat insects which destroy orange and lime
crops ) source of food chemicals that are obtained are used by
humans ( ex: chitin from crustacean shells is used to dress wounds
and to make thread for surgical stitches )
Slide 25
The Largest living Arthropod! is the Japanese Spider Crab with
a leg span of 4 meters and a weight of 20kg. This crab has a life
expectancy of 100 years.