1 / 29

Phylum Arthropoda :

Phylum Arthropoda :. Blueprint for Success Chapter 14 and 15. Characteristics of Arthropods. Modified segmentation – body regions specialized for specific functions ( tagmatization ). Chitinous exoskeleton used for support and protection Paired, jointed appendages

onofre
Download Presentation

Phylum Arthropoda :

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Phylum Arthropoda: Blueprint for Success Chapter 14 and 15

  2. Characteristics of Arthropods • Modified segmentation – body regions specialized for specific functions (tagmatization). • Chitinous exoskeleton used for support and protection • Paired, jointed appendages • Growth accompanied by molting (ecdysis)

  3. Characteristics of Arthropods • Ventral nervous system • Reduced coelom • Open circulatory system where blood is released into tissue spaces (hemocoel) • Complete digestive tract • Metamorphosis often present

  4. Arthropods • Successful in almost all habitats on the earth. • Most abundant animals – Several million species identified • 30 to 50 million species may yet be undescribed • Triploblastic, protostome development • Exhibit bilateral symmetry • Four aspects contribute to arthropod success. • 1. Metamerism • 2. Exoskeleton • 3. The Hemocoel • 4. Metamorphosis

  5. Metamerism • Segmentation, most evident externally • Each external segment bears a pair of appendages • Body cavity not divided internally • Permits the specialization of regions of the body for specific functions • Regional specialization = Tagmatization • Body regions (tagmata) specialized for: feeding, sensory perception, locomotion, visceral functions.

  6. The Exoskeleton • External, jointed skeleton which encloses arthropods • Provides support, protection, and prevents water loss • System of levers for muscle attachment and movement • Secreted by epidermal cells • Epidermis covered by exoskeleton on outside • Consists of two layers: • 1. Epicuticle = outermost, waxy lipoprotein layer • 2. Procuticle/Endocuticle = bulky inner layer made of chitin

  7. The Exoskeleton • Hardening of the procuticle provides armor-like protection • Modifications of the exoskeleton • Formation of joints • Sensory receptors (bristles, lenses, etc) • Gas exchange • Must be periodically shed for growth (ecdysis)

  8. The Exoskeleton • Epicuticle and Procuticle: epicuticle exocuticle procuticle endocuticle epidermis

  9. The Hemocoel • Provides an internal cavity for the open circulatory system of arthropods • Allows for the exchange of nutrients, wastes, and (sometimes) gases

  10. Metamorphosis • Indirect development, a significant change in physiology as the immature form becomes an adult • Reduces competition between adults and immature stages

  11. Metamorphosis • Evolution of arthropods has resulted in an increasing divergence of body forms, behaviors, and habitats between immature and adult stages. • Ex: Larval crabs feed on plankton, adult crabs prowl sandy bottoms for live prey. • Ex: Caterpillar feeds on leafy vegetables, adult butterfly feeds on nectar from flowers.

  12. Subphylum Crustacea • Examples: • Crayfish, crabs, lobster, shrimp, barnacles and copepods. • Two unique characteristics: • 1. Two pairs of antennae • 2. Biramous appendages • Five classes of crustaceans and numerous orders • Class Malacostraca** • Class Maxillopoda** • Class Branchiopoda • Class Remipedia • Class Cephalocarida

  13. Class Malacostraca • “Soft Shell” • Largest class of crustaceans: • crabs, lobsters, crayfish, shrimp, krill, isopods • Body divided into two regions • 1. Cephalothorax (fusion of sensory/feeding and locomotion tagmata) • 2. Abdomen (a muscular tail)

  14. Class Malacostraca • Paired, biramous appendages in both body regions • Appendages on Cephalothorax: • Pairs 1 and 2 – Antennae (TWO pairs!) • Pairs 3 through 5 – Mouth appendages • Mandible Pair (Chewing) • Maxillae (Food handling) • Pairs 6 through 8 – Maxillipeds • Accessory sensory and food handling appendages • Pairs 9 through 13 – Pereopods (Walking legs) • Cheliped (Pincher-like) • Appendages on Abdomen • Pleopods (Swimmerets) • Telson used

  15. Class Malacostraca

  16. Class Malacostraca Reproduction • All crustaceans are dioecious • Mating occurs after molting of the female • In females, developing eggs attach to pleopods and are brooded until hatached • In males, pleopods are modified into claspers and used for sperm transfer • Crayfish have direct development

  17. Class Malacostraca Feeding Predators, herbivores, scavengers Foregut includes an enlarged stomach, specialized for grinding Midgut = “intestine” Short hindgut ends in anus and used for water and salt regulation

  18. Class Malacostraca Gas Exchange & Circulation Sensory & Regulation Ventral nervous system Compound eyes Crayfish: Excretion organs are called “green glands” Other crustaceans: maxillary glands • Gills in gill chamber • Between the carapace and body wall • Muscular Heart • Dorsal, anterior, and posterior arteries empty into sinuses of hemocoel

  19. Class Maxillopoda • Includes Barnacles and Copepods • Copepods are most abundant crustacean • Marine and Freshwater • Barnacles are sessile • Marine only • Most monoecious • Attach to various substrates • Some are parasitic

  20. Subphylum Hexapoda • Most successful land animals in terms of numbers of species and individuals • Bodies divided into three tagmata • Five pairs of head appendages • Three pairs of legs on thorax

  21. Class Insecta • 30 Orders within Class Insecta! • Adult Generalized Insect Characterized by: • Body divided into head, thorax, abdomen • Three pairs of legs • Two pairs of wings

  22. Class Insecta Body Plan • Head • Single pair of antennae • Mouthparts • Compound eyes • 0 to 3 ocelli (simple eyes) • Thorax • Three segments: prothorax, mesothorax, metathorax • One pair of legs attaches to each thoracic segment • Pair of wings attach at margin between mesothorax and metathorax • Abdomen • 10 to 11 abdominal segments

  23. Insect Flight • Insects utilize many forms of locomotion: walk, run, jump, swim, but flight is perhaps the most important • Insects were the first animals to fly • Important from an evolutionary perspective! • Wings most likely evolved from outgrowths of the thorax which protects the legs • Required thermoregulation • Some insects use a synchronous (direct) flight mechanism which others use an asynchronous (indirect) flight mechanism.

  24. Insect Flight • Synchronous (Direct) Flight • Used by butterflies, dragonflies, and grasshoppers. • Flight muscles act on wing bases • A single nerve impulse in flight muscles results in a single wing cycle • Asynchronous (Indirect) Flight: • Used by flies and wasps • Flight muscles act on body wall • Changes in shape of the thorax cause wing movements. • A single nerve impulse results in many cycles of the wings

  25. Insect Feeding • Variations in mouthparts include specializations for sucking or siphoning plant or animal fluids • Mouthparts: • Labrum- upper liplike structure, sensory and not derived from paired appendages • Mandibles- chewing mouthparts • Maxillae- have cutting surfaces and a sensory palp • Labium-sensory lower lip • All aid in food handling

  26. Insect Digestive System • Long and straight and consists of the foregut, midgut, and a hindgut. • Foregut • Behind pharynx is a crop that is used for storage • Proventriuculus or gizzard moves food to midgut helps grind • Midgut • Aids in digestion and absorption • Gastric cecae increase surface area • Hindgut • Primarily involved with reabsorption of water

  27. Insect Gas Exchange • Gas exchange with air requires a large surface area for the diffusion of gases • Accomplished through highly branched systems of chitin-lined tubes called tracheae • Tracheae open to outside of body through spiracles • Spiracles can close to prevent water loss • Most insects have ventilating mechanisms • Moves air into and out of tracheal system • Contracting flight muscles • Passive suction (vacuum) draws air in • Abdominal muscle contraction (pump)

  28. Insect Circulation • Open circulatory system similar to other arthropods but blood vessels less well developed • Blood carries nutrients, hormones, wastes • Blood is not important in gas exchange • Most insects are ectotherms, but some generate heat using flight muscles

  29. Insect Sensory Functions • Ganglion in head region • Sense organs specialized for functioning on land • Insects are capable of some learning have a memory • Bees recognize flowerlike objects • When bees are rewarded with nectar, they will choose flowers with that same odor in subsequent trials • Capable of detecting light • Used in orientation, navigation, feeding, etc • Compound eyes are well developed in adults

More Related