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Download Phylum Arthropoda - Biology Junction
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Phylum Arthropoda (The Arthropods) •By far and away, the most successful animal group ever to live •Consists of over 1 million named species, 2 of every 3 animals are arthropods. ~ 1018 individuals. –Inhabit all ecosystems •General characteristics •All have a hard exoskeleton •Composed of protein and chitin –Allows for great variation in function - biological "swiss army knives" –Must molt as they grow –Limits their size •Have well developed body segments and appendages •Have well developed sensory organs including true eyes and antennae •Have open circulatory systems & special gas exchange organs Could this be possible? Subphylum Chilicerata (arachnids, horseshoe crabs & sea spiders) • Divided into 3 classes; Arachnida, Merostomata & Pycnogonida • Body divided into 2 regions – Abdomen – Cephalothorax (fused head & thorax) • Lack jaws • Have 6 appendages & no antennae – First appendages form chilicerae (frequently fangs) Class Arachnida (Spiders, Scorpions, Ticks & Mites) • Very diverse class • Most species parasitic or predatory • Many possess book lungs for gas exchange • Spiders are able to produce a strong polymer - silk • Chilicera in form of fangs Spiders More Spiders… Tarantula Black Widow For the true arachnophobe… The brown recluse and its bite wounds The Camel Spider Ticks & Mites Ticks & Lyme Disease… Common Mites Dust Mite Common Mite Scorpions Class Picogonida (Sea Spiders) Class Merostomata • Ancient group of species • Changed little over 350 million years • Aquatic, mostly found on Atlantic & gulf coasts of United States Subphylum Uniramai (3 Classes) • Class Insecta (insects) • Class Chilopoda (Centipedes) • Class Diplopoda (Millipedes) Class Insecta (the insects) • Far & away the most diverse of animal groups – More types of insects alone than all other animal groups combined – Inhabit all terrestrial & freshwater ecosystems. – Success largely attributed to coevolution with flowering plants. Insect Body Plan • • Insects have 6 legs 3 body parts – Head – Thorax – Abdomen • • • Most insects have wings, however in many species these are vestigal Have advanced excretory system composed of malphygian tubules Exchange gasses through a complex tracheal system Vision • Have complex compound eye which is usually extremely sensitive to motion and allows 3600 vision • Most insects see well into the UV spectrum Feeding / Mouthparts • Insects usually have specialized jaws/mouthparts suited to their ecological niche Metamorphosis • Most insects undergo a process of metamorphosis - 2 types • Incomplete metamorphosis – Larva similar to adult, with differing body proportions – Undergoes a series of molts resulting in adult phenotype Complete Metamorphosis • Larva is very unlike adult phenotype • Envelopes self in a coccoon or chrysalis where body breaks-down and reforms into adult form. Classes Chiopoda & Diplopoda • Millipedes (diplopoda) are segmented worm-like animals – Have 2 pairs of legs per segment – Primarily herbivores & decomposers • Centipedes (Chilopoda) – Usually terrestrial carnivores – Have 1 pair of antennae – Are often poisonous, using modified front claws to immobilize prey Centipedes vs. Millipedes Centipede Millipede Subphylum Crustacea • Includes crabs, lobsters, crayfish, shrimp, krill & barnacles • Over 40,000 species • Appendages are often highly specialized • Gas exchange is usually through gills • Many species taste delicious in butter Some Crustaceans Crayfish Marine Maine Lobster Crabs Barnacles
