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Phylum Arthropoda
- most species rich phlyum
- most ecologically important group of animals
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Arthropoda Characteristics
- Cephalization
- Jointed appendages
- segmented body
- sclerotized cuticle made of chitin
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Cephalization
head region is composed of several segments with specialized functions
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Importance of sclerotized cuticle
- acts as exoskeleton
- provides support
- surface for muscle attachment
- molt
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Cephalothorax
head and thorax are fused together
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Body segments roles
- head: eating and sensory
- thorax: locomotion
- abdomen: digestion and reproduction
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Subphylum Crustacea (crabs, lobsters, shrimp etc)
mostly marine some freshwater and terrestrial
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Crustacean Morphology
- 2 pairs of antennae
- compound eyes
- often cephalothorax (covered by carapace)
- main mouthparts are mandibles
- appendages help guide food
- exoskeleton hardened by calcium carbonate
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Crustacean use of different limbs
- Thoracic: locomotion
- Abdominal: swimming, filter feeding and holding eggs
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How do crustaceans breath?
- aquatic: gills
- terrestrial: trachea
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Crustacean life cycle
- separate sexes
- sperm transferred through copulation
- brood eggs
- direct and indirect development
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Crustacean Ecology
- detrivores (consume waste), scavengers and predators
- filter-feed (shrimp and barnacles)
- commensals or parasites
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Hexapods (insects and springtails)
- 6 legged arthropods
- class instecta and collembola
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Shared features of Hexapods and Myriapods
- one pair of antennae
- mandibles
- trachea
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Hexapod morphology
- Head: one pair of antennae
- Thorax: 3 pairs of jointed legs
- Abdomen: no paired jointed appendages
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Class Collrmbola (Hexapod) "springtails"
- appendages at end of body for jumping
- osmoregulation (controls concentration of fluids)
- collophore- produces sticky glue
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Class Insecta (Hexapod)
- pair of segmented terminal appendages (cerci)
- compound eyes and ocelli (simple eye)
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Insecta wings
- primitive groups lack wings
- most adults have wings
- wings are synapomorphy of clade
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Types of Hexapoda life cycles
incomplete metamorphosis: juveniles share same appearance and habitat as adult
complete metamorphosis: wings develop in pupa stage, different morphology and habitat
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Hexapod Reproduction
no hermaphrodites
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Types of Hexapoda fertilization
Spermatophore: Collembolans and apertygote, indirect sperm transfer
Copulation: pterygote, direct sperm transfer
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Myriapoda (millipedes and centipedes)
- at least three pairs of legs
- less tagmatized
- direct development
- only terrestrial
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Class diplopoda (millipedes)
- 2 pairs of legs/segment
- detritivorous or herbivorous
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Class Chilopoda (centipedes)
- mainly carnivorous
- one pair legs/segment
- one pair of legs modified as mouthparts
- can be poisonous
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Chelicerata (scorpians, horseshoe crabs, spiders, mites)
- lack antennae
- chelicerae as moutparts (2 or 3 segmented pincers)
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Chelicerata body plan
- 2 main tagmata
- Cephalothorax: 6 pairs of limbs, eyes
- abdomen: may have appendages, contains cut and reproductive organs
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Class Arachnida (chelicerata)-spiders, mites and scorpions
- separate sexes
- only feed on fluids
- simple eyes (ocelli)
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Class Arachnida- Order Araneae (spiders)
- 2 segmented chelicerae (mouth parts)- excretes poision
- 0-4 pairs of ocelli
- trachea and/or book lungs
- spinnerets on abdomen
- maternal care and complex courtship
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Class Arachnida- Order Scorpiones (scorpions)
- crush or sting prey
- externally digest
- courtship and brood
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Class Arachnida- Order Acari (mites)
- no separation between cephalothorax and abdomen
- external segmentation
- 2-3 segmented chelicerae
- 0-2 pairs ocelli
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Chelicerata- Class Xiphosura (horseshoe crabs)
- not related to crabs
- compound eyes
- book gills (resemble pages of book)
- long terminal spine=tail
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Xiphosura ecology
- scavenge on dead plants and animals
- prey on small soft bodied animals
- spawn just above tide
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Deuterostomia
- phyla: Echinodermata & Chordata
- triploblastic
- radial intermediate cleavage
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