1. Phylum Arthropoda

2. 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.)

3. 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

4. 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

5. 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

6. Metamorphosis

7. Arthropod Exoskeleton
Secreted by the epidermis
Functions:
Support 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)

8. Subphylum Trilobitomorpha
Trilobites inhabited Earth’s oceans from
600 mya – 345 mya – are now extinct
Body oval & flattened _ divided into three segments (longitudinal)
Rolled into a ball for protection

9. 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

10. Phylum Arthropoda 2 minor classes: 5 major 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

11. Classification of Arthropods
Centipedes – 1 pr legs/segment
Millipedes – 2 prs legs/segment
Insects – 3 pairs of legs
Arachnids – 4 pairs of legs
Crustaceans – 5 pairs of legs

12. 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

13. Subphylum Myriapoda- Class Chilopoda

14. Subphylum Myriapoda- Class Diplopoda
1000 leggers
Cylindrical worm like with 2/prs legs/seg
Decomposers or herbivores
>1000 species in US
Short antenna
Non-toxic

15. Subphylum Myriapoda- Class Diplopoda

16. 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

17. 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

18. Subphylum Crustacea Shrimp Lobster Krill Pill bug Crabs Crayfish
Barnacles (sessile)

19. Subphylum Crustacea- Class Remipedia
Cave-dwelling
30 segments with uniform, biramous appendages
Carribean, Indian Ocean, Canary Islands, Australia

20. Subphylum Crustacea

21. Subphylum Crustacea- Class Branchiopoda
Freshwater mostly
Leaflike appendages for respiration, filter feeding and locomotion
Fairy, brine and clam shrimp and water fleas

22. 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

23. Subphylum Crustacea- Class Malacostraca
Modified appendages for crawling, feeding or swimming
Lobsters, crayfish, crabs, shrimp, and isopods

24. Subphylum Hexapoda- Class Insecta
>750,000 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

25. Subphylum Hexapoda- Class Insecta
Three body divisions
Head
Thorax
Abdomen
Exoskeleton
12 Inches—Largest
1MM-Smallest
Rapid growth rate
Exponential
Most mature < 1 year
Display almost every color

26. 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)

27. Subphylum Hexapoda- Class Insecta
Pheromones- External hormones used for communication (especially in finding mates)

28. Subphylum Hexapoda- Class Insecta
>390 million years old
Coevolved with plants (Especially flowering plants)
1st insects were flightless

29. 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

30. Subphylum Hexapoda- Class Insecta
Harmful insects:
Disease vectors
Crop/food destruction
Textile destruction

31. Subphylum Hexapoda- Class Insecta Morphology
Mimicry- Resemble something you are not in order to survive
Protective resemblance

32. 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

33. Subphylum Hexapoda- Class Insecta Hierarchy

34. Subphylum Chelicerata- Class Arachnida
Spiders
Mites/ticks
Scorpions

35. 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
>30,000 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

36. Subphylum Chelicerata- Class ArachnidaOrder - Araneae

37. 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 aren’t
One of the oldest forms of life on Earth

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

39. 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

40. Class Merostomata

41. Class Pycnogonida