Chapter 14 Phylum Arthropoda

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Chapter 14- Phylum Arthropoda

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Phylum Arthropoda Facts

• Arthropods inhabit virtually every environment on
  earth
• Includes
• Crayfish
• Lobsters
• Spiders
• Scorpions
• Insects
• Considered to be the most successful animal group
• More than 1 million known species (6-9 million
  est.)

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Phylum Arthropoda Characteristics

• Microscopic to 12 ft length (King Crab)
• Jointed appendages- Structures extending from
  body wall
• Bilaterally symmetrical
• Evolutionary links to annelids
• Many are toxic
• Many vector (transmit) pathogens
• Many beneficial

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Phylum Arthropoda

• Rigid exoskeleton for support and protection
• Molting occurs during growth
• Paired, jointed appendages
• Ventral nervous system (ventral nerve cord)
• Reduced coelom
• Open circulatory system
• Complete digestive tract
• Malpighian tubules- Excretory units
• Respiration through tracheae (network of fine
  tubes) and spiracles (structures where air
  enters)
• Metamorphosis often occurs during development

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Arthropod Metamorphosis

• Metamorphosis radical change in body form
• Complete Metamorphosis- Includes pupa stage
• Incomplete metamorphosis- No pupa stage
• Results in reduced competition between immature
  forms and adults
• Eat different food
• Occupy different habitats
• Example caterpillar vs. butterfly

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Metamorphosis
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Arthropod Exoskeleton

• Secreted by the epidermis
• Functions
• Support http//www.youtube.com/watch?vzXhdr0T
  pOwYBack to results
• Protection
• Prevent water loss
• Muscle attachment/movement
• Two layers
• Epicuticle (outside) waxy, impermeable to
  water
• Procuticle chitin
• Must be shed to allow growth (molt)

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Subphylum Trilobitomorpha

• Trilobites inhabited Earths oceans from
• 600 mya 345 mya are now extinct
• Body oval flattened _ divided into three
  segments (longitudinal)
• Rolled into a ball for protection

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Phylum Arthropoda- Living Subphyla

• Hexapoda
• Class Insecta
• Myriapoda
• Class Diploda
• Class Chilopoda
• Crustacea
• Class Remipedia
• Class Cephalocarida
• Class Branchiopoda
• Class Malacostraca (Orders Decapoda and Isopoda)
• Class Maxillopoda
• Chelicerata
• Class Arachnida (Orders Scorpions, Acari, and
  Araneae)
• Class Merostomata
• Class Pycnogonida

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Phylum Arthropoda

• 2 minor classes
• Class Merostomata- Horseshoe crabs
• Class Pycnogonida- Sea spiders
• 5 major classes
• Chilopoda centipedes
• Diplopoda millipedes
• Malacotsraca crabs, lobster, crayfish,shrimp
• Insecta insects
• Arachnida spiders, scorpions, mites, chiggers

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Classification of Arthropods

• Centipedes 1 pr legs/segment
• Millipedes 2 prs legs/segment
• Crustaceans 5 pairs of legs
• Insects 3 pairs of legs
• Arachnids 4 pairs of legs

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Subphylum Myriapoda- Class Chilopoda

• Centipedes
• 100 leggers
• Flattened worm like w/1 pr legs/seg
• Carnivores
• Possess a pair of poison claws or legs just
  behind the head which are used to paralyze their
  prey
• Feed on insects or small animals
• Most centipedes are beneficial
• Large species found in the tropics (length of up
  to 18 inches)
• Can inflict painful bites

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Subphylum Myriapoda- Class Chilopoda
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Subphylum Myriapoda- Class Diplopoda

• 1000 leggers
• Cylindrical worm like with 2/prs legs/seg
• Decomposers or herbivores
• gt1000 species in US
• Short antenna
• Non-toxic

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Subphylum Myriapoda- Class Diplopoda
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Subphylum Myriapoda- Millipedes and Centipedes

• Life Cycle
• Millipede eggs are deposited in masses in the
  soil.
• Young millipedes have fewer segments than the
  adult, but they add segments at each molt of the
  outer shell, or exoskeleton.
• Molting occurs 7-10 times before maturity.
• Young millipedes mature the second year after
  hatching.
• Some species may live for several years.
• Similarly, centipedes molt several times, adding
  legs and body segments with each molt

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Subphylum Crustacea

• Body segmented with hardened Limbs
• Limbs generally with two branches
• Two pairs of antennae
• Two compound eyes (eyes with many lenses)
• Body with 7 or more pairs of sometimes very
  different appendages for feeding, locomotion and
  sex
• Respiration by gills
• Nauplius- Distinctive larval stage with three
  pairs of branched appendages
• Although originally aquatic, many crustaceans are
  adapted to life on land

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Subphylum Crustacea

• Shrimp
• Lobster
• Krill
• Pill bug
• Crabs
• Crayfish
• Barnacles (sessile)

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Subphylum Crustacea- Class Remipedia

• Cave-dwelling
• 30 segments with uniform, biramous appendages
• Carribean, Indian Ocean, Canary Islands, Australia

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Subphylum Crustacea
http//www.youtube.com/watch?veKPrGxB1Kzc
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Subphylum Crustacea- Class Cephalocarida

• Small and marine
• Uniform, leaflike triramous appendages

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Subphylum Crustacea- Class Branchiopoda

• Freshwater mostly
• Leaflike appendages for respiration, filter
  feeding and locomotion
• Fairy, brine and clam shrimp and water fleas

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Subphylum Crustacea- Class Maxillopoda

• Five head, six thoracic, and four abdominal
  somites with a telson
• Variously fused segments
• No appendages on reduced abdomen
• Barnacles and copepods

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Subphylum Crustacea- Class Malacostraca

• Modified appendages for crawling, feeding or
  swimming
• Lobsters, crayfish, crabs, shrimp, and isopods

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Subphylum Hexapoda- Class Insecta

• gt750,000 species
• Upwards of 3 million species
• Outnumber all other plant and animal groups
• Found in all environments
• 10,000 ft. high
• Some fly 100s of KM per week

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Subphylum Hexapoda- Class Insecta

• Three body divisions
• Head
• Thorax
• Abdomen
• Exoskeleton
• 12 InchesLargest
• 1MM-Smallest
• Rapid growth rate
• Exponential
• Most mature lt 1 year
• Display almost every color

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Subphylum Hexapoda- Class Insecta

• Open circulatory system
• Spiracles along abdomen used for breathing
• Highly modified mouth parts (mandibles)
• Some beetles can chew through lead or zinc
• Well developed tube within a tube digestive
  system
• Well developed nervous system
• Sight- two types of eyes
• Smell/taste-Use of antennae and feet
• Hearing- tympanum (eardrum)

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Subphylum Hexapoda- Class Insecta

• Pheromones- External hormones used for
  communication (especially in finding mates)

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Subphylum Hexapoda- Class Insecta

• gt390 million years old
• Coevolved with plants (Especially flowering
  plants)
• 1st insects were flightless

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Subphylum Hexapoda- Class Insecta

• Entomology- Study of insects and other arthropods
• Helpful or harmful
• Helpful insects
• Pollinators
• Research and discovery- fruit fly for genetic
  research
• Food producers- honey
• Textiles- Silk beeswax
• Biological control agents

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Subphylum Hexapoda- Class Insecta

• Harmful insects
• Disease vectors
• Crop/food destruction
• Textile destruction

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Subphylum Hexapoda- Class Insecta Morphology

• Mimicry- Resemble something you are not in order
  to survive
• Protective resemblance

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Subphylum Hexapoda- Class Insecta Hierarchy

• Ants, termites, hornets, wasps, and some bees
• Social hierarchy
• Caste system
• King and queen
• Large number of individuals function as one unit
• Division of labor
• Physical appearance of individuals depends on
  their caste placement

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Subphylum Hexapoda- Class Insecta Hierarchy
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Subphylum Chelicerata- Class Arachnida

• Spiders
• Mites/ticks
• Scorpions

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Subphylum Chelicerata- Order Araneae

• Most familiar spiders
• Cephalothorax (head fused to thorax)and abdomen
• All toxic
• No antennae
• Use pedipalps ( 2nd pair of appendages modified
  to catch and handle prey) and walking legs as
  sensory organs
• gt30,000 Species/3,000 in U.S.
• Tarantulas largest
• Body 2.5 in, legs 9-10 in.

• Many, but not all spiders web builders
• Spinneretes- Appendages that secrete silk)
• Liquid feeders
• Inject digestive enzymes into prey and drink
  juices
• Use powerful jaws to crush exoskeleton- then
  digest and eat

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Subphylum Chelicerata- Class ArachnidaOrder -
Araneae
http//www.asterpix.com/console/?avi10313601
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Subphylum Chelicerata- Class Arachnida

• Order Scorpions
• Tropical and subtropical
• 0.5 to 8 IN.
• Stinger on end of tail
• Pedipalps are pinchers
• Nocturnal
• Can be deadly but many arent
• One of the oldest forms of life on Earth

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Other Arachnids

• Order Acari
• Ticks, mites, and chiggers
• Found everywhere
• Omnivorous/scavengers/parasites
• Many blood feeders
• Disease vectors
• Rocky Mountain Spotted Fever
• Lyme Disease

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Other Chelicerates

• Class Merostomata-
• Subclass Xiphosura- Horseshoe crabs (Limulus)
• Marine with book gills
• Not actually crabs
• Shallow water on Atlantic coast
• Feed on worms, bivalves, and small animals
• Subclass Eurypterida- Extinct giant water
  scorpions
• Class Pycnogonida- Sea spiders
• Reduced abdomen
• No special respiratory/excretory organs
• Four to six pairs of legs

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Class Merostomata
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Class Pycnogonida