Arthropoda Notes PDF

**Arthropoda** **Phylum Arthropoda** - Gr. ***Arthron***, joint, + ***pous***, ***podos***, foot - Most numerous animals on earth (900,000 species) - Spiders, scorpions, ticks, mites, crustaceans, millipedes, centipedes, insects and some smaller groups. **[Structure and organization\...

**Arthropoda** **Phylum Arthropoda** - Gr. ***Arthron***, joint, + ***pous***, ***podos***, foot - Most numerous animals on earth (900,000 species) - Spiders, scorpions, ticks, mites, crustaceans, millipedes, centipedes, insects and some smaller groups. **[Structure and organization\ ]** - Segmented body, metameric body - Segments are specialized for a variety of purposes, forming functional groups (Tagmata) 1. Head and thorax are two tagmata 2. Head, thorax and abdomen 3. Cephalothorax and abdomen - Triploblastic coelomates with well developed organ systems - No backbone - Cuticular exoskeleton (chitin and tanned protein) - ecdysis (or molting) **Nutrition** - with **complete** digestive system - Mouthparts are modified from appendages and adapted for different methods of feeding - exhibit all modes of feeding: carnivorous, herbivorous, scavengers, filter-feeding **Locomotion** - each somite bears a single pair of jointed appendages **Reproduction** - dioecious and internal fertilization - may be oviparous or ovoviviparous - ***life cycle is metamorphosis*** which include molting process or ecdysis (shedding of exoskeleton) - Few species exhibit ***parthenogenesis*** - form of reproduction in which an unfertilized egg develops into a new individual, occurring commonly among insects and certain other arthropods; **virgin origin** **Respiration and Circulation** - Respiration by body surface, gills, tracheae or book lungs - Open circulatory system - Poikilothermic **Excretion** - excretory organs - malpighian tubules - excretory glands such as antennal, coxal, and maxillary glands **Nervous System** - similar to annelid plan, with dorsal brain connected by a ring around the pharynx to a double nerve chain of ventral ganglia; fusion of ganglia in some species; well- developed sensory organs. **I. Subphylum Trilobitomorpha (Latin: three-lobed form)** C:\\Documents and Settings\\Rubie\\Desktop\\Syste Zoo Lab\_MSI\\09 Arthropoda\\ppt pics\\trilobite1.jpg - extinct trilobites - consist of three tagmata: head, thorax, and pygidium - each somite (except for the last) has two lobes or biramous type of appendages - inner lobe/**endopod**: walking - outer lobe/**exopod**: burrowing, swimming, filter-feeding, respiration II**. Subphylum Chelicerata (Greek: claw)**  **body with two tagmata:** - cephalothorax (**prosoma**) and - Abdomen (**opisthosoma**) **with six pairs of appendages all attached to prosoma** 1. first pair: **chelicerae** which are feeding organs, 2. second pair: **pedipalps** which could be feeding or sensory structures 3. last four pairs as **walking legs** **members do not have antennae** - includes spiders, ticks, scorpions, sea spiders, mites, harvestmen (daddy longlegs) and horseshoe crabs **II. Subphylum Chelicerata** **[Class Merostomata]** Figure 30 - Prosoma and opisthosoma - Appendages on the opisthosoma are flattened and modified for gas exchange as 'book gills' - Elongated terminal portion called telson - Includes horseshoe crabs **(*Limulus polyphemus*)** and extinct giant water scorpions **II. Subphylum Chelicerata** **[Class Arachnida]** (Gr. *arachne*, spider)  - Segmented or unsegmented abdomen (opisthosoma) with or without appendages and generally distinct from cephalothorax - Chiefly oviparous - No true metamorphosis - Includes scorpions, spiders, ticks, and mites **[Class Arachnida]** a. Scorpion b. Pseudoscorpion c. Red spider mite d. Black-legged tick e. Tick f. Solpugid g. Jumping spider h. Common spider i. Opilionid (harvestmen or daddy long-legs) **II. Subphylum Chelicerata** **Class Pycnogonida** (Greek: thick knee) C:\\Documents and Settings\\Rubie\\Desktop\\Syste Zoo Lab\_MSI\\09 Arthropoda\\ppt pics\\seaspider2.jpg - Body not divided into tagmata - Unique proboscis at anterior end, with an opening at its tip to suck fluid from cnidarians - Variable number of walking legs among species - Includes sea spiders **III. Subphylum Crustacea (Latin: a crust)** - mostly marine and few are terrestrial and freshwater - carapace as their exoskeleton which is composed of chitin and calcium carbonate - body is divided into cephalothorax and abdomen - appendages are biramous (two-lobed) - use gills for respiration - Includes brachiopods, ostracods, isopods, amphipods, copepods, barnacles, shrimps, hermit crabs, crabs, lobsters **III. Subphylum Crustacea\ ** **Class Malacostraca** - isopods (pill bugs, sow bugs, woodlice), amphipods (sand fleas), decapods (crabs, lobsters, shrimps, hermit crabs), krills  **Class Branchiopoda** \- brine (fairy) shrimp, clam shrimp, water fleas **Class Cirripedia** -- the barnacles  **Class Ostracoda** -- the ostracods **Class Copepoda** -- the copepods **IV. Subphylum Uniramia (Latin: a branch)\ ** - all are terrestrial - includes millipedes, centipedes and insects - body is divided into three tagmata (body segments): head, thorax and abdomen - their exoskeleton contains tanned protein - head with only one pair of antennae - appendages are uniramous and are present on head and thorax but may be reduced or absent in the abdomen - use tracheae for respiration - possess malpighian tubules for excretion of body wastes **[IV. Subphylum Uniramia]** **[Class Chilopoda]**  - '100 legs' - live in moist places and are carnivorous - with flattened bodies with each segment bearing a pair of jointed walking legs - the appendages of first somite form poison claws - possess a pair of antennae, a pair of mandibles and one to two pairs of maxillae - oviparous - Centipedes **[Class Diplopoda]** Figure 30 - '1000 legs' - body consists of 25 to 100 segments, each bearing two pairs of legs - head with a pair of antennae and two pairs of mouthparts - are herbivorous and live in a leaf mold - oviparous - Millipedes **[Class Insecta]** **insects** **IV. Subphylum Uniramia** **[Class Insecta]** - insects are the most diverse species of arthropods - mostly found in the tropics - consist of three tagmata: head, thorax and abdomen - the head bears a pair of compound eyes, with a pair of antennae and three ocelli - Mouthparts modified for different food habits - Thorax with 2 pairs of wings (sometimes 1 pair or none) and 3 pairs of jointed legs - Usually oviparous - Gradual or abrupt metamorphosis - Mouthparts modified for different food habits - Mouthparts modified for different food habits [IV. Subphylum Uniramia] Class Insecta Subclass Apterygota -- wingless; silverfishes and springtails Subclass Pterygota -- 'true' or winged insects Order Odonata - dragonflies and damselflies Order Orthoptera - grasshoppers, crickets, locusts Order Isoptera - termites Order Lepidoptera- butterflies and moths Order Diptera - true flies such as mosquitoes Order Coleoptera - beetles Order Anoplura - sucking lice Order Hymenoptera - ants, bees, wasps Order Siphonaptera - fleas Order Hemiptera - true bugs like water striders, aphids, cicadas Order Blattaria -- cockroaches Order Mantodea -- preying mantids   **Taxonomic Summary**