Phylum Arthropoda

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This presentations shows the various members of the invertebrate phylum of arthropods.

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ARTHROPODS:

05 Nov. 2009 Arthropoda.ppt 1 ARTHROPODS Phylum Arthropoda

Phylum Arthropoda (jointed feet ):

05 Nov. 2009 Arthropoda.ppt 2 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!!

Phylum Arthropoda:

05 Nov. 2009 Arthropoda.ppt 3 Phylum Arthropoda How can we explain the success of the arthropods? Exoskeleton!

Phylum Arthropoda:

05 Nov. 2009 Arthropoda.ppt 4 Phylum Arthropoda Exoskeleton of chitin and protein (= cuticle) structure: epicuticle (oily, waxy) exocuticle (chitin & protein) endocuticle (chitin only) epidermis secretes cuticle

Problems associated with exoskeleton.:

05 Nov. 2009 Arthropoda.ppt 5 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.

Problems associated with exoskeleton.:

05 Nov. 2009 Arthropoda.ppt 6 Problems associated with exoskeleton. MOVEMENT Solution: Joints in exoskeleton. Exocuticle absent from joints; may form hinges. Endocuticle alone allows flexibility.

Problems associated with exoskeleton.:

05 Nov. 2009 Arthropoda.ppt 7 Problems associated with exoskeleton. Problem 2. GROWTH Solution: Molting

Molting (1):

05 Nov. 2009 Arthropoda.ppt 8 Molting (1) Secretion of "molting fluid" to dissolve old endocuticle.

Molting (2):

05 Nov. 2009 Arthropoda.ppt 9 Molting (2) New cuticle formed under old exocuticle. Break out of old cuticle Old cuticle breaks at line of weakness

Molting (3):

05 Nov. 2009 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.

Growth stages:

05 Nov. 2009 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)

Problems associated with exoskeleton.:

05 Nov. 2009 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

Problems associated with exoskeleton.:

05 Nov. 2009 Arthropoda.ppt 13 Problems associated with exoskeleton. Problem 3. SENSORY INPUT vision clear cuticle over compound or simple eyes

Problems associated with exoskeleton.:

05 Nov. 2009 Arthropoda.ppt 14 Problems associated with exoskeleton. Problem 3. SENSORY INPUT hearing tympanum = endocuticle, vibrates like eardrum trichobothria (right )

Benefits of Exoskeleton: to individuals::

05 Nov. 2009 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.

Benefits of Exoskeleton: to the phylum::

05 Nov. 2009 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

Tagmosis:

05 Nov. 2009 Arthropoda.ppt 17 Tagmosis Head (~ 4-6 segments) feeding, sensation Head appendages mandibles, maxillae, maxillipeds, chelicerae antennae

Tagmosis:

05 Nov. 2009 Arthropoda.ppt 18 Tagmosis Thorax (~ 3-6 segments) locomotion, grasping. Thoracic appendages walking legs, wings chelipeds

Tagmosis:

05 Nov. 2009 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)

Tagmosis:

05 Nov. 2009 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 (1 st pair modified as chelipeds)

Other arthropod characters:

05 Nov. 2009 Arthropoda.ppt 21 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.

Other arthropod characters:

05 Nov. 2009 Arthropoda.ppt 22 Other arthropod characters Respiratory systems Gills in aquatic/marine arthropods Tracheal systems in most terrestrial arthropods Book lungs (modified gills) in spiders & scorpions

Other arthropod characters:

05 Nov. 2009 Arthropoda.ppt 23 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

Distinguishing Characters of Ph. Arthropoda:

05 Nov. 2009 Arthropoda.ppt 24 Distinguishing Characters of Ph. Arthropoda Jointed exoskeleton Tagmosis Compound eyes

Classification of Arthropoda:

05 Nov. 2009 Arthropoda.ppt 25 Classification of Arthropoda Subphylum Trilobita Subphylum Crustacea Subphylum Chelicerata Subphylum Uniramia

Classification of Arthropoda:

05 Nov. 2009 Arthropoda.ppt 26 Classification of Arthropoda Subphylum Trilobita Class trilobites Three-lobed head & body (left, middle, right) Diverse in Paleozoic ~540-240 MYA Extinct

Classification of Arthropoda:

05 Nov. 2009 Arthropoda.ppt 27 Classification of Arthropoda Subphylum Crustacea 2 pr. Antennae (antennules, antennae) Cephalothorax 13 segments & appendage pairs Abdomen variable among Classes

Classification of Arthropoda:

05 Nov. 2009 Arthropoda.ppt 28 Classification of Arthropoda Subphylum Crustacea Class shrimps Class barnacles

Classification of Arthropoda:

05 Nov. 2009 Arthropoda.ppt 29 Classification of Arthropoda Subphylum Chelicerata Cephalothorax Jaws are chelicerae Pedipalps 4 pr. Walking legs Abdomen

Classification of Arthropoda:

05 Nov. 2009 Arthropoda.ppt 30 Classification of Arthropoda Subphylum Chelicerata Class Horseshoe crabs Horseshoe crabs Scorpions ??

Classification of Arthropoda:

05 Nov. 2009 Arthropoda.ppt 31 Classification of Arthropoda Subphylum Chelicerata Class Arachnids Lost compound eyes Spiders “Daddy-long-legs” Amblypygi Mites & ticks more Scorpions ??

Classification of Arthropoda:

05 Nov. 2009 Arthropoda.ppt 32 Classification of Arthropoda Subphylum Uniramia Legs unbranched Class Centipedes 1 st legs are “fangs”

Classification of Arthropoda:

05 Nov. 2009 Arthropoda.ppt 33 Classification of Arthropoda Subphylum Uniramia Class Millipedes Double segments (2 pr. legs per segment)

Classification of Arthropoda:

05 Nov. 2009 Arthropoda.ppt 34 Classification of Arthropoda Subphylum Uniramia Class Insects Head, thorax, abdomen 2 pr. Wings ~800,000 species, majority of all arthropods

Why are Arthropods so successful?:

05 Nov. 2009 Arthropoda.ppt 35 Why are Arthropods so successful? Exoskeleton  tagmosis  evolution of flight  speciation  10 6 species of insects.

Why are Arthropods so successful?:

05 Nov. 2009 Arthropoda.ppt 36 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!