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09 June 2011. Arthropoda.ppt. 2. Phylum Arthropoda. Phylum Arthropoda Greek: arthro = jointed, pod = foot Huge group, > 1,000,000 species.estimate: 1,000,000 spp. arthropods 1,190,000 spp. animals ~ 84% of all animal species are arthropods!! . 09 June 2011. Arthropoda.ppt. 3. Phylum Arthropoda .
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1. 09 June 2011 Arthropoda.ppt 1 ARTHROPODS Phylum Arthropoda
2. 09 June 2011 Arthropoda.ppt 2
3. 09 June 2011 Arthropoda.ppt 3 Phylum Arthropoda Body pla n
Tube-in-tube, bilateral symmetry, protostomous, “split” coelom
Marine, aquatic, terrestrial
even Antarctica !
Cell and tissue organization
Triploblastic, complex organs
~ 30,000 genes in genome, (same as for mammals)
4. 09 June 2011 Arthropoda.ppt 4 Phylum Arthropoda Unique, distinguishing characters
Huge group, > 1,000,000 species.
How can we explain the success of the arthropods?
Exoskeleton!
5. 09 June 2011 Arthropoda.ppt 5 Phylum Arthropoda Exoskeleton of chitin and protein (= cuticle)
structure:
epicuticle (oily, waxy)
exocuticle (chitin & protein)
endocuticle (chitin only)
epidermis secretes cuticle
6. 09 June 2011 Arthropoda.ppt 6 Problems associated with exoskeleton. Problem 1. MOVEMENT
Solution: Joints in exoskeleton.
arthro-, = joint
-pod, = leg, foot
Exocuticle absent from joints; may form hinges.
Endocuticle alone allows flexibility.
7. 09 June 2011 Arthropoda.ppt 7 Problems associated with exoskeleton. Problem 2. GROWTH
Solution: Molting
8. 09 June 2011 Arthropoda.ppt 8 Molting (1) Secretion of "molting fluid" to dissolve old endocuticle.
9. 09 June 2011 Arthropoda.ppt 9 Molting (2) New cuticle formed under old exocuticle.
Break out of old cuticle
Old cuticle breaks at line of weakness
10. 09 June 2011 Arthropoda.ppt 10 Molting (3) Inflate with water/air to increase size while skeleton soft,
but soft skeleton & gravity limit size;
arthropods are mostly small.
Hardening of new exocuticle.
11. 09 June 2011 Arthropoda.ppt 11 Growth stages Arthropod passes thru 3-20+ growth stages in life cycle.
Some stop molting as adults (insects, most spiders)
Some continue to molt (crayfish, tarantulas)
12. 09 June 2011 Arthropoda.ppt 12 Problems associated with exoskeleton. Problem 3. SENSORY INPUT
touch
sensory setae connected to neurons
smell & taste
hollow sensory setae w/ chemosensitive nerve endings
13. 09 June 2011 Arthropoda.ppt 13 Problems associated with exoskeleton. Problem 3. SENSORY INPUT
vision
clear cuticle over compound or simple eyes
14. 09 June 2011 Arthropoda.ppt 14 Problems associated with exoskeleton. Problem 3. SENSORY INPUT
hearing
tympanum = endocuticle, vibrates like eardrum
trichobothria (right ?)
15. 09 June 2011 Arthropoda.ppt 15 Benefits of Exoskeleton: to individuals: Support
Locomotion
lever system
walk, swim, fly
Mechanical protection (armor)
Retards evaporation (in air) and/or osmosis (in water)
water balance.
16. 09 June 2011 Arthropoda.ppt 16 Benefits of Exoskeleton: to the phylum: Reduction of coelom & segmentation
Abandoned hydrostatic system of annelid-like ancestor)
Coelom reduced to pericardial cavity
Segments fused = tagma, tagmata
Tagmosis
Specialization of body regions (= tagmata)
Specialization of appendages
17. 09 June 2011 Arthropoda.ppt 17 Tagmosis Head (~ 4-6 segments)
feeding, sensation
Head appendages
mandibles,
maxillae,
maxillipeds,
chelicerae
antennae
18. 09 June 2011 Arthropoda.ppt 18 Tagmosis Thorax (~ 3-6 segments)
locomotion, grasping.
Thoracic appendages
walking legs,
wings
chelipeds
19. 09 June 2011 Arthropoda.ppt 19 Tagmosis Abdomen (~8- 30+ segments)
respiration, reproduction, etc.
Abdominal appendages
abdominal gills (aquatic insect larvae)
swimmerets (crayfish)
filtering legs (barnacles)
gonopods (crayfish, etc.)
spinnerets (spiders)
20. 09 June 2011 Arthropoda.ppt 20 Tagmosis Number of segments/legs in each tagma varies by subphylum, class.
Cephalothorax of 6 segments in Chelicerata
1 pr. chelicerae
1 pr. pedipalps
4 pr. walking legs
Cephalothorax of 13 segments in Crustacea (shrimps)
2 pr. antennae
1 pr. mandibles
2 pr. maxillae
3 pr. maxillipeds
5 pr. walking legs (1st pair modified as chelipeds)
21. 09 June 2011 Arthropoda.ppt 21 Phylum Arthropoda Ways the needs of cells are met
1. Food
Herbivores, predators, detritivores, parasites, filter feeders, . . .
2. O2 and CO2 exchange
Gills—usu. modified legs,
Book lungs,
Tracheal systems
3. Waste removal
Diffusion from gills, Malphigian tubules
22. 09 June 2011 Arthropoda.ppt 22 Other arthropod characters Open circulatory system
Dorsal heart pumps hemolymph over brain
Hemolymph moves through hemocoel back toward heart
Ostia (holes) in sides of heart let hemolymph in to go around again.
23. 09 June 2011 Arthropoda.ppt 23 Other arthropod characters Respiratory systems
Gills in aquatic/marine arthropods
Tracheal systems in most terrestrial arthropods
Book lungs (modified gills) in spiders & scorpions
24. 09 June 2011 Arthropoda.ppt 24 Phylum Arthropoda Special concerns of a multicellular animal
Circulation: Open circulatory system,
Coordination,
Structural support, Movement,
Maintenance of homeostasis—water balance.
25. Phylum Arthropoda Special concerns of a multicellular animal
Circulation: Open circulatory system, (analogous to that in Mollusca)
Dorsal aorta
Hemocoel
Pores (ostia) valved
Text fig. 42.3 09 June 2011 Arthropoda.ppt 25
26. 09 June 2011 Arthropoda.ppt 26 Other arthropod characters Nervous system resembles that of annelid
Dorsal brain with nerves around esophagus
Paired ventral nerve cords
Segmental ganglia
Often fused into 1-2 ganglia in each tagma
27. 09 June 2011 Arthropoda.ppt 27 Phylum Arthropoda Special concerns of a multicellular animal
Exoskeleton for Structural support, Movement,
Maintenance of homeostasis—water balance
Malphigian tubules, etc.
Reproduction
Usually sexual, some parthenogenic
28. 09 June 2011 Arthropoda.ppt 28 Distinguishing Characters of Arthropoda Jointed exoskeleton
Tagmosis
Compound eyes
29. 09 June 2011 Arthropoda.ppt 29 Classification of Arthropoda Subphylum Trilobita
Subphylum Crustacea
Subphylum Cheliceriformes
Subphylum Myriopoda
Subphylum Hexapoda
30. 09 June 2011 Arthropoda.ppt 30 Classification of Arthropoda Subphylum Trilobita
Class Trilobita
Three-lobed head & body (left, middle, right)
Diverse in Paleozoic ~540-240 MYA
Extinct
31. 09 June 2011 Arthropoda.ppt 31 Classification of Arthropoda Subphylum Crustacea
2 pr. Antennae (antennules, antennae)
Cephalothorax
13 segments & appendage pairs
Abdomen
variable among Classes
32. 09 June 2011 Arthropoda.ppt 32 Classification of Arthropoda Subphylum Crustacea
Class crabs
Class barnacles
33. 09 June 2011 Arthropoda.ppt 33 Classification of Arthropoda Subphylum Chelicerata
Cephalothorax
Jaws are chelicerae
Pedipalps
4 pr. Walking legs
Abdomen
34. 09 June 2011 Arthropoda.ppt 34 Classification of Arthropoda Subphylum Chelicerata
Class Horseshoe crabs
Horseshoe crabs
Scorpions ??
35. 09 June 2011 Arthropoda.ppt 35 Classification of Arthropoda Subphylum Chelicerata
Class Arachnids
Lost compound eyes
Spiders
“Daddy-long-legs”
vinegaroons
mites & ticks
more
Scorpions ??
36. 09 June 2011 Arthropoda.ppt 36 Classification of Arthropoda Subphylum Myriapoda
Legs unbranched
Head & body
Class Centipedes
1st legs are “fangs”
37. 09 June 2011 Arthropoda.ppt 37 Classification of Arthropoda Subphylum Myriapoda
Class Millipedes
Double segments (2 pr. legs per segment)
38. 09 June 2011 Arthropoda.ppt 38 Classification of Arthropoda Subphylum Hexapoda
Class Insects
Head, thorax, abdomen
2 pr. Wings
~800,000 species, majority of all arthropods
39. 09 June 2011 Arthropoda.ppt 39 Classification of Arthropoda Subphylum Hexapoda
Class Insects
Incomplete metamorphosis
Dragonflies
Orthoptera
Hemiptera, Homoptera
Complete metamorphosis
Coleoptera (beetles)
Hymenoptera (wasps, ants, bees)
Diptera (flies)
40. 09 June 2011 Arthropoda.ppt 40 Why are Arthropods so successful? Exoskeleton ? tagmosis ? evolution of flight ? speciation ? 106 species of insects.
41. 09 June 2011 Arthropoda.ppt 41 Why are Arthropods so successful? Exoskeleton ? protection from water loss ? early colonization of land ? head start.
Arthropods were diverse and widespread on land before vertebrates!