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PHYLUM ARTHROPODA. ZLY 103: Animal Diversity. Delivered by SHITTU Olalere Dept. of Zoology, University of Ilorin, Nigeria. Introduction. Gk. “ arthros ”– joint + “ podos ”– foot is the most extensive, successful, ubiquitous and diverse phylum in the animal kingdom.
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PHYLUM ARTHROPODA ZLY 103: Animal Diversity Delivered by SHITTU Olalere Dept. of Zoology, University of Ilorin, Nigeria
Introduction • Gk. “arthros”– joint + “podos”– foot is the most extensive, successful, ubiquitous and diverse phylum in the animal kingdom. • Common throughout marine, freshwater, terrestrial, and even aerial environments. • They dominate life in terms of their relative large size, numbers and species diversity • They are the first set of organisms to Colonize the land. • Feeding mode is highly varied, almost all organic substances are edible to arthropods
Introduction • They have innate ability to defend and protect self from danger in any given habitation. • They share numerous ecological niche, e.g. trophic niche with man. • They possess a very efficient food acquisition and utilization mechanism • Arthropods share common features to annelids and are believed to have evolved from annelid-like ancestors. • The Onychoporans share so many characters with annelids, like; segmentation, metamerism, discrete muscular arrangements, ganglia on ventral nerve cord, etc.
General Characteristics • They are triploblastic, bilateral symmetrical, metamerically segmented coelomates. • Entire body is covered with a chitinous exoskeleton called cuticle. • The cuticle is completely non-living, non cellular, multilayered, stout and rigid. It is secreted by the epidermis. • Body usually segmented and jointed externally (divided into 3 major parts (Tagmata): head, thorax, abdomen
General Characteristics • They possess jointed appendages that are equipped for feeding, sensory reception, defense and locomotion; with hardened exoskeleton containing chitin with Ecdysis (molt) at intervals. • Their muscles run in discrete bundles and operates on a lever system for movement. • They possess a central nervous system (CNS) made up of a dorsal brain connected to a double, ventral and solid ganglionated nerve cord. • The coelom is reduced to cavities of the gonads, pericardium and haemocoel.
General Characteristics • Presence of a open vascular system with no septa consisting of a dorsal contractile tubular heart with blood flowing in haemocoelic sinuses. • Complete digestive tract: Mandible-chewing or proboscis- sucking ending in an anus. • Improved respiration through gills, trachea, book lungs or body surface to support the active and energetic life style due to loss of gaseous exchange between body wall. • Sensory organs include antennae and hairs, simple and compound eye
General Characteristics • Arthropods have improved excretory system which is mediated by glands like antennary, coxal/maxillary glands that functions as coelomoducts. • Terrestrial forms use a more efficient and water conserving malphighiantubules. • Reproduces (mostly sexually), one to several larval stage or direct development in some species.
Phylum Arthropoda (Taxa) The Chelicerates The Mandibulates • Pincher-like mouthparts - chelicerae & pedipalps • No antennae • Two body regions; cephalothorax & abdomen • Four pairs of legs • Horseshoe crabs & arachnids are the only living groups • Mouthparts are mandibles normally chewing sideways • 1 or 2 pairs of antennae • Various body region arrangements: - cephalothorax & abdomen, head & trunk, head, thorax & abdomen • Variable leg numbers • Insects, crustaceans & myriapods
Diagnostic Features of the 4 Arthropods Subphyla 1. Trilobita Habitat: Aquatic, benthos Body division: Head, Thorax, Pygidium Appendages: Head - 1pair of antenna, 1pair of compound eye, 4pairs of mouthparts. Thorax -1pair / somite. Appendage Type: Biramous. Respiratory organ: Extinct. Excretory organ: Extinct. Reproductive organ & Development: Extinct Exoskeleton: Chitinous with CaCO3
CLASS TRILOBITA Trilobites
Diagnostic Features of the 4 Arthropods Subphyla 2. Crustacea Habitat: Aquatic, few terrestrial. Body division: Cephalothorax, Abdomen Appendages: Cephalothorax - 2pairs of antenna, 1pair of stalked compound eye, 1pair of mandibles, 2pairs of maxillae, 1pair each on the 8 thoracic segments Abdomen -1pair / segment on the 6 segments. Appendage Type: Biramous. Respiratory organ: Gills. Excretory organ: Antennary or maxillary gland.
Diagnostic Features of the 4 Arthropods Subphyla Crustacea Reproductive organ & Development: Separate sexes, external fertilization, indirect development – nauplius larva Exoskeleton: Massive, strong & impregnated with calcium salts Examples: Branchiopodae.g. Fairy shrimps, Water fleas Maxillopoda e.g. Copepods, Barnacles Malacostraca e.g. Crabs, lobsters, Shrimps.
Diagnostic Features of the 4 Arthropods Subphyla • Isopoda – sow bugs or pill bugs • Amphipoda - sand fleas, amphipods • Cirripedia - barnacles • Decapoda - crabs, lobster, shrimp • several other minor orders Crustacea
Diagnostic Features of the 4 Arthropods Subphyla Crayfish cephalothorax (Decapoda) Crab Crustacea Sowbug (Isopoda), a terrestrial crustacean Barnacle Lobster
Diagnostic Features of the 4 Arthropods Subphyla 3. Chelicerata Habitat: Terrestrial with some aquatic forms. Body division: Prosoma, Opisthosoma Appendages: Prosoma- 1pair of chelicera, 1pair of pedipalp, numerous simple eyes, 4pairs of walking legs, Opisthosoma – No appendages except on last segment. Appendage Type: Uniramous. Respiratory organ: Lung books or tracheal system. Excretory organ: Coxal gland or malpighian tubule.
Diagnostic Features of the 4 Arthropods Subphyla Chelicerata Dog Tick Wolf spider Lycosa tarentula Horse shoe crabs Goliath bird – eating tarentula
Diagnostic Features of the 4 Arthropods Subphyla Chelicerata Reproductive organ & Development: Separate sexes, internal fertilization, direct development Exoskeleton: Epicuticle impregnated with wax. Examples: Merostomatae.g. Horse shoe crab, Limulus Arachnidae.g.Spiders, Scorpions, Mites & Ticks Pycnogonidae.g. Sea spiders
pedipalp chelicera (fang) cephalothorax narrow waist abdomen Diagnostic Features of the 4 Arthropods Subphyla Chelicerata Spider Anatomy
pedipalps & chelicerae cephalothorax abdomen Mite and Tick Body Regions
Diagnostic Features of the 4 Arthropods Subphyla 4. Uniramia Habitat: Terrestrial with some aquatic forms. Body division: Head and Trunk or as in Trilobita Appendages: Head - 1pair of antenna, 1pair of simple or compound eye, 1pair of mandibles, 2pairs of maxillae, Trunk/Thorax – 1 or 2pairs of walking legs on each side of the segment except the abdomen Appendage Type: Uniramous. Respiratory organ: Tracheal system. Excretory organ: Malpighian tubule
Diagnostic Features of the 4 Arthropods Subphyla Uniramia Reproductive organ & Development: Separate sexes, internal fertilization, Metamorphosis Exoskeleton: Cuticle hardened with proteins, epicuticle waxed in insects. Examples: Dipolopodae.g. Millipedes Chilopodae.g.Centipede Insectae.g. Mosquitoes, Housefly, Grasshopper, Termites, Ants, Bugs etc.
Uniramia Order Coleoptera Weevil Order Orthoptera migrating locust Beetle Order Chilopoda Centipede Order Hymenoptera Fire ant Solenopsis invicta Order Diplopoda Millipede
Class Insecta • Members constitute about 75% of known animal species. • They are responsible for the success of Arthropods. • They represent the largest and the most diverse class of animals. • The study of insects is known as Entomology • Spectacularly, insects have only three pairs of limbs. • They have only two pairs of wings on their thorax. • Mainly two subclasses, viz: • Apterygota (wingless, small, primitive, no metamorphosis) • Pterygota (winged, size varies, complete & Incomplete metamorphosis). • There are 27 orders distinguishable according to wing structure, mouthparts and metamorphosis.
Diversity • Insects that have piercing and sucking mouthparts are called BUGS while BEETLES are insects distinguished as those having forewings modified into hard wing cases that cover and protect the hind wings and abdomen!
LIFE CYCLE OF A DRAGONFLY (CLASS INSECTA ORDER ODONATA)
LIFE CYCLE OF A FRUIT FLY (CLASS INSECTA ORDER DIPTERA)
(Larva) Caterpillar (Pupa) Chrysalis LIFE CYCLE OF A BUTTERFLY (CLASS INSECTA ORDER LEPIDOPTERA)
LIFE CYCLE OF A GRASSHOPPER (CLASS INSECTA ORDER ORTHOPTERA)
Economic importance • Serve as food source for both animals and humans • Aid in the propagation of plant species by means of cross-pollination • Control the population of some harmful organisms • Some act as scavengers or saprotrophs
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