insects Study guide

insects Study guide - Study guide: Insects classifications...

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Study guide: Insects classifications Phylum Arthropoda characterisitics : Metamerism- body is segmented Exoskeleton- body covered with a hard external skeleton -good for small things , protects body from damage -bones are better for larger things Bilateral symmetry-body can be divided into two indentical halves Jointed appendages- each segment may have one pair of appendages -ex: legs, wings, mouthparts, antennae Open circulatory system- blood washes over organs and is not entirely closed by blood vessels -our system is a closed one Ventral nerve cord- one nerve cord, similar to our spinal column -Arthropods have ganglia that are segmentally arranged, instead of one large nerve mass, such as a brain -arthropods do have brains, but not all of their nervous tissue is in one area Tracheal respiratory system -composed of tubes that carry oxygen as a gas in air to tissues where it is needed -with holes(spiricals) through the body that admit air into the network of tubes *tubes open to outside of body to breathe, air goes to muscles that need O2 -they do not have lungs and their blood doesn’t carry oxygen Evolution: probably evolved from a peripatus-like ancestor(phylum onychophora) which in turn evolved from a segmented worm -Subphylum Chelicerata: -includes spiders,scorpions, mites, whipscorpions -they have fang-like pincers (chelicerae) to pick apart their food -Subphylum Crustacea: -lobsters, crayfish, shrimp -Subphylum Atelocerata: -millipedes, centipedes, and insects(many have mandibles or jaws, or some resultant modification) -Subphylum Trilobita(extinct) -lived during the Cambrian period about 600 mill ago -marine, lots on the bottom of the oceans -common as fossils -many segments w/o specialization -small to large (>1 foot) in size Arthropods 2: subphyla, classes, and orders Subphylum Crustacea (crustaceans) -primarily live in aquatic enviroments so they breathe with gills -Characteristics: *feeding structures that move side to side(mandibles) *2 pairs of antennae *2 major body regions: cephalothorax(head+chest), abdomen(stomach)
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*5-7 pairs of legs -most common examples: *class: Malacostraca *order: decapoda- lobsters, crayfish, crabs, shrimp * order isopoda(equal foot)- -sowbugs, pillbugs -roly-polys -some species are among the few terrestrial -detritus feeders -some of the terrestrial ones can roll into a ball -harmless Subphylum Chelicerata -ticks, mites, spiders, scorpions, etc. -most are terrestrial -65,000 known species(8,000 in N.A.) -they all have: *feeding structures that move up and down like snake fangs, but not hollow( like chelicerae=crustaceans) *no antennae *two major body regions: cephalothorax(head+chest) and abdomen(stomach)= same as crustaceans *four pairs of legs Class Arachnida: Order Araneae- Spiders -generally carnivorous *hold prey with chelicerae, and pour enzyme-rich salivary juices over them *digestion is mostly externa *fang-like mouthparts, all have poisons, but few spiders are a threat to humans -most spin silk
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insects Study guide - Study guide: Insects classifications...

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