PowerPoint PresentationSlide 2How do the Arthropods fit in?Phylum ArthropodaFossil RecordSlide 6Slide 7Arthropoda CharacteristicsWhat characteristics have enabled Arthropods to achieve such great diversity and abundance?Slide 10Ecdysis (molting)Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Subphylum Trilobita (Trilobitmorpha)Subphylum ChelicerataSubphylum Chelicerata Class Merostomata Horseshoe crabs have been essentially unchanged for ~250 million yearsClass MerostomataSlide 24Subphylum Chelicerata Class ArachnidaClass ArachnidaSlide 27Slide 28Subphylum Chelicerata Class PycnogonidaSubphylum CrustaceaSlide 31Subphylum Crustacea Class BranchiopodaSubphylum Crustacea Class OstracodaSubphylum Crustacea Class CopepodaSubphylum Crustacea Class CirripediaClass CirripediaSlide 37Subphylum Crustacea Class MalacostracaClass MalacostracaSlide 40Subphylum Crustacea ParasitismSubphylum Crustacea CommensalismsSubphylum Crustacea MutualismsSlide 44Slide 45HomologySerial HomologyAnalogy- 2 individuals- structures have same developmental origin and same or different functions- 2 structures on 1 individual- 2 individuals- structures have different developmental origins but same functionquill & hairbat wing & handcheliped & swimmeretbird wing & insect winghomologyanalogyserial homologyHow do the Arthropods fit in?unknown common ancestorPoriferaCnidariaPlatyhelminthes NemerteaNematodaRotiferaAnnelidaArthropodaPhylum Arthropoda“joint-footed” animalsFossil RecordDevonian periodThese fossilized tracks may push the date of land arthropods back into the Cambrian540 million years oldA very ancient group with a ~500 million year fossil recordFossil RecordThese fossilized tracks may push the date of land arthropods back into the Cambrianfirst dinosaurs, mammals, birdsMillions of years ago0First invertebrates213 360First reptilesFirst amphibians65 – end of dinosaursFirst fishesFirst land plants5055907004,600First ArthropodsCambriantodayArthropodaall other phylaPhylum Arthropoda• the largest phylum• comprises ~80% of all known animalsArthropoda CharacteristicsTriploblasticCephalizationBilateral SymmetryOrgan level of organizationEucoelomateProtostomeWhat characteristics have enabled Arthropods to achieve such great diversity and abundance?Arthropoda CharacteristicsExoskeleton• hardened external cuticle secreted by the epidermis• composed of chitin; has internal ridges/projections called apodemes to which muscles attach • benefits: protection without loss of mobility• limits growth must be “molted” • limits ultimate body size because of weightEcdysis (molting)• molting fluid dissolves old endocuticle• new exocuticle is secretedexocuticleendocuticle• new exocuticle is formed under the old one• old exocuticle ruptures• ecdysis! the animal backs out of old exoskeleton• new endocuticle forms under exocuticle• exocuticle hardensunder hormonal controlepicuticleArthropoda CharacteristicsTagmatization and jointed appendages• the fusion of segments into blocks called tagmata (sing:tagma) that are specialized for certain functions • usually each tagma has a pair of jointed appendages• appendages may be highly modified with tagmata being specialized for certain functions (e.g. feeding, moving, sensory)• appendages are essentially hollow levers that are moved by well-developed striated muscles (flexors and extensors) and are capable of fast, powerful movementArthropoda CharacteristicsRespiratory System• on land: most have a respiratory system that consists of tubes that deliver air directly to tissues and cells• in water: most have gills• these systems allow for a higher metabolic rate and level of activityArthropoda CharacteristicsSensory System• similar to Annelida (ventral nerve cord, cerebral ganglia/brain…)• possess a variety of sensory organs(e.g. simple and compound eyes, antennae, chemoreceptors, sensory hairs…)Arthropoda CharacteristicsComplex Behavior• have complex innate behaviors and some are capable of learning• some even show communication and cooperation!Spiny lobster cooperative behaviorDr. Herrnkind: http://bio.fsu.edu/~herrnlab/Spiny lobster migration behaviorArthropoda CharacteristicsMetamorphosis• most have a larval stage that differs morphologically and behaviorally from the adult• reduces competition between larvae and adults by allowing them to occupy different ecological nichesArthropoda Characteristics• complete with regional specializationDigestive SystemCirculatory System• open circulatory system consisting of a hemocoel (main body-cavity) filled with hemolymph (blood)• no external cilia/flagellaArthropoda CharacteristicsExcretion• usually glands, some classes have specialized excretory systemsReproduction• usually sexual and dioecious • usually internal fertilizationPhylum ArthropodaClass MerostomataClass PycnogonidaClass ArachnidaSubphylum Trilobita Subphylum Chelicerata Subphylum Crustacea Subphylum Uniramia Class Branchiopoda Class MalacostracaClass Copepoda *Class Ostracoda *Class Cirripedia *Class Chilopoda Class DiplopodaClass Insecta* In your textbook, these are listed as subclasses within the class Maxillopoda. But follow what is here and in lab.(Arthropoda II)Subphylum Trilobita (Trilobitmorpha)• all are extinct• the most diverse of the extinct arthropod groups (~5000 genera)Subphylum Chelicerata• no antennae• 6 pairs of appendages: 1st pair = pincer, fang-like chelicerae2nd pair = pedipalps 3rd – 6th pair = walking legs • body divided into 2 tagmataprosoma: consists of the head and all the legsopisthosoma:consists of the abdomenSubphylum ChelicerataClass MerostomataHorseshoe crabs have been essentially unchanged for ~250 million yearsClass Merostomataopisthosoma prosomatelsoncompound eyecarapacebook gillswalking legscheliceraeClass MerostomataSubphylum ChelicerataClass ArachnidaClass Arachnida spiders, scorpions, ticks, mites, chiggers, daddy longlegsThey usually have several adaptations for life on land:• book lungs or tracheal system or both• waxy cuticlepedipalpsClass Arachnida• arachnids as parasites• chiggers (mites) and ticksClass Arachnida• arachnids as disease vectors• Lyme disease is caused by infection with a bacteria that is transmitted by tick bitesBorelliaDeer tickSubphylum ChelicerataClass Pycnogonida• sea spiders• ~1000 marine species• males carry the eggsSubphylum Crustacea• most are marine, some terrestrial and freshwater•
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