Transcript Phylum Arthropoda - Richmond School District

Phylum Arthropoda
“jointed” “foot”
80% of all animals are arthropods…..
76% of those are insects…..
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Major Classes of Arthropods
Above: Subphylum Myriapoda,
Class Diplopoda: includes the
millipedes
Above left: Subphylum Myriapoda,
Class Chilipoda: includes the
centipedes
Lower Right: Subphylum Hexapoda,
Class Insecta: includes all 6 legged
insects
Above: Subphylum Crustacea, Class
Maxillopoda: includes the barnacles
Above Left: Subphylum
Chelicerata Class Arachnida:
includes the spiders, mites
and scorpions
Lower right: Subphylum
Crustacea, Class
Malacostraca: includes the
lobsters, crab and shrimp
Shared characteristics of Arthropods
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Coelomate and bilaterally symmetrical
Jointed appendages
Exoskeleton of chitin secreted by the epidermis
3 body regions (head, thorax, and abdomen)
Respiration by body surface, gills, trachea, or book lungs
Open circulatory system
Sensory organs are well-developed: compound eyes,
tympanum (drum-like ear) antenna (touch, smell, chemical
reception)
Complete digestive systems with mouth, specialized
organs and anus
Dioecious: fertilization is usually internal
Developed nervous system with dorsal brain connected by
a ring and double ventral nerve cords
Found in marine, freshwater, terrestrial and aerial
environments
Let’s take a closer look at a few
different Classes of Arthropods
Class Insecta
• Exoskeleton made of chitin
• Have a head segmented into
6 with sensory antennae and
compound eyes
• Have a thorax with attached
segmented legs and possibly
wings
• Have an abdomen with 11
segments which houses
most of the digestive,
respiratory, excretory and
reproductive systems
• Insects respire through a
system of internal tubes
and sacs that lie directly
next to the circulatory
system,therefore the
circulatory system does
not need closed vessels
• Most insects hatch from
eggs which are fertilized
by sexual reproduction
(see ladybugs at top
right)
• Insects molt as they
grow in size (undergo
metamorphosis)
Class Maxillopoda : The Barnacles
The Barnacle Life Cycle
Includes 2 larval stages
1. NAUPILUS
• spend their time floating
around in the current, eating
and molting
• last approx. 2 weeks
2. CYPRID
• strong swimmer
• Settles in a safe, productive
environment
• Cements itself headfirst to
surface and undergoes
metamorphosis into a
barnacle
• As the cyprid
metamorphosizes it
develops 6 hard armor
plates around its body
• The adult barnacle has
feathery legs that protrude
to capture food and
gametes when spawning
• Barnacles are
hermaphroditic
Famous Barnacle Fact:
Barnacles have the
largest penis to body
size ratio of any
species in the animal
kingdom
Class Malacostraca : The Crustaceans
• Head and thorax are
often fused into
cephalothorax
• Head includes 6
segments with
antennules, antennae
and mouthparts with
appendages called
maxillipeds
• 8 thoracic segments
• Cephalothorax is
almost completely
covered by a carapace
• 6 abdominal segments
often used for
swimming
Hermit Crab
Spiny King Crab
• Eyes are compound
stalked or sessile
(stalked eyes allow
the crustacean to pull
them in for protection
or see in many
different directions)
• 5 pairs of walking
legs, some with
modified pincers
• 2-chambered
stomach
• Centralized nervous
system
Above: Lobster
Above: Pacific White Cleaner Shrimp
Left: Decorator Crab: will cover its
body in algae etc. in order to
camouflage itself with its surroundings
Pair of Lobster
Spiny Lobster
Prawn
Hermit Crab
Ecological Roles of Arthropods
Burrowing shrimp and Goby fish living in
Symbiosis
• shrimp cleans and digs a burrow where they
both live
•When danger approaches, the goby fish
touches the shrimp with its tail to warn it
(shrimp is blind) and both hide in the burrow
• 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
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.