04 Nov. 2014Arthropoda.ppt1 ARTHROPODS Phylum Arthropoda

04 Nov. 2014Arthropoda.ppt2 Phylum Arthropoda (jointed feet ) Huge group, > 1,000,000 species. estimate: 1,000,000 spp. arthropods 1,190,000 spp. animals ~ 84% of all animal species are arthropods!!

04 Nov. 2014Arthropoda.ppt3 Phylum Arthropoda How can we explain the success of the arthropods? Exoskeleton!

04 Nov. 2014Arthropoda.ppt4 Phylum Arthropoda Exoskeleton of chitin and protein (= cuticle) structure: –epicuticle (oily, waxy) –exocuticle (chitin & protein) –endocuticle (chitin only) –epidermis secretes cuticle

04 Nov. 2014Arthropoda.ppt5 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.

04 Nov. 2014Arthropoda.ppt6 Problems associated with exoskeleton. MOVEMENT Solution: Joints in exoskeleton. –Exocuticle absent from joints; may form hinges. –Endocuticle alone allows flexibility.

04 Nov. 2014Arthropoda.ppt7 Problems associated with exoskeleton. Problem 2. GROWTH Solution: Molting

04 Nov. 2014Arthropoda.ppt8 Molting (1) Secretion of "molting fluid" to dissolve old endocuticle.

04 Nov. 2014Arthropoda.ppt9 Molting (2) New cuticle formed under old exocuticle. Break out of old cuticle  Old cuticle breaks at line of weakness

04 Nov. 2014Arthropoda.ppt10 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.

04 Nov. 2014Arthropoda.ppt11 Growth stages Arthropod passes thru growth stages in life cycle. Some stop molting as adults (insects, most spiders) Some continue to molt (crayfish, tarantulas)

04 Nov. 2014Arthropoda.ppt12 Problems associated with exoskeleton. Problem 3. SENSORY INPUT touch –sensory setae connected to neurons smell & taste –hollow sensory setae w/ chemosensitive nerve endings

04 Nov. 2014Arthropoda.ppt13 Problems associated with exoskeleton. Problem 3. SENSORY INPUT vision  clear cuticle over compound or simple eyes

04 Nov. 2014Arthropoda.ppt14 Problem 3. SENSORY INPUT hearing  tympanum = endocuticle, vibrates like eardrum  trichobothria (right  ) Problems associated with exoskeleton.

04 Nov. 2014Arthropoda.ppt15 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.

04 Nov. 2014Arthropoda.ppt16 Benefits of Exoskeleton: to the phylum: Reduction of coelom & segmentation  Abandoned hydrostatic system of annelid-like ancestor)  Coelom reduced to pericardial cavity Segments fused = Tagmosis  Specialization of body regions (= “tagmata”)  Specialization of appendages

04 Nov. 2014Arthropoda.ppt17 Tagmosis Head (~ 4-6 segments)  feeding, sensation Head appendages  mandibles,  maxillae,  maxillipeds,  chelicerae  antennae

04 Nov. 2014Arthropoda.ppt18 Tagmosis Thorax (~ 3-6 segments)  locomotion, grasping. Thoracic appendages  walking legs,  wings  chelipeds

04 Nov. 2014Arthropoda.ppt19 Tagmosis Abdomen (~ segments)  respiration, reproduction, etc. Abdominal appendages  abdominal gills (aquatic insect larvae)  swimmerets (crayfish)  filtering legs (barnacles)  gonopods (crayfish, etc.)  spinnerets (spiders)

04 Nov. 2014Arthropoda.ppt20 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 (1 st pair modified as chelipeds)

04 Nov. 2014Arthropoda.ppt21 Other arthropod characters Open circulatory system  Dorsal heart pumps hemolymph over brain  Hemolymph moves through hemocoel back toward heart  Holes/valves in sides of heart let hemolymph in to go around again.

04 Nov. 2014Arthropoda.ppt22 Other arthropod characters Respiratory systems  Gills in aquatic/marine arthropods  Tracheal systems in most terrestrial arthropods  Book lungs (modified gills) in spiders & scorpions

04 Nov. 2014Arthropoda.ppt23 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

04 Nov. 2014Arthropoda.ppt24 Distinguishing Characters of Ph. Arthropoda Jointed exoskeleton Tagmosis Compound eyes

04 Nov. 2014Arthropoda.ppt25 Classification of Arthropoda Subphylum Trilobita Subphylum Chelicerata Subphylum Myriopoda Subphylum Crustacea Subphylum Hexapoda

04 Nov. 2014Arthropoda.ppt26 Classification of Arthropoda Subphylum Trilobita  Class Trilobites Three-lobed head & body (left, middle, right) Diverse in Paleozoic ~ MYA Extinct

04 Nov. 2014Arthropoda.ppt27 Classification of Arthropoda Subphylum Chelicerata  Cephalothorax Jaws are chelicerae Pedipalps 4 pr. Walking legs  Abdomen

04 Nov. 2014Arthropoda.ppt28 Classification of Arthropoda Subphylum Chelicerata –Class Horseshoe crabs Horseshoe crabs Scorpions ??

04 Nov. 2014Arthropoda.ppt29 Classification of Arthropoda Subphylum Chelicerata  Class Arachnids Lost compound eyes Spiders “Daddy-long-legs” Vinegaroons Mites & ticks Scorpions more

04 Nov. 2014Arthropoda.ppt30 Classification of Arthropoda Subphylum Myriopoda  Class Centipedes One pair legs per segment, 1 st legs are “fangs”

04 Nov. 2014Arthropoda.ppt31 Classification of Arthropoda Subphylum Myriopoda  Class Millipedes Double segments (2 pr. legs per segment)

04 Nov. 2014Arthropoda.ppt32 Classification of Arthropoda Subphylum Crustacea  2 pr. Antennae (antennules, antennae)  Cephalothorax 13 segments & appendage pairs  Abdomen variable among Classes

04 Nov. 2014Arthropoda.ppt33 Classification of Arthropoda Subphylum Crustacea  Class shrimps  Class barnacles

04 Nov. 2014Arthropoda.ppt34 Classification of Arthropoda Subphylum Hexapoda  Class Insects Head, thorax, abdomen 2 pr. Wings ~800,000 species, majority of all arthropods

04 Nov. 2014Arthropoda.ppt35 Why are Arthropods so successful? Exoskeleton  tagmosis  evolution of flight  speciation  10 6 species of insects.

04 Nov. 2014Arthropoda.ppt36 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!