1 / 70

Chapter 30

Chapter 30. Arthropods. I. Features of Arthropods. A typical arthropod is a segmented , coelomate invertebrate animal with bilateral symmetry, an exoskeleton , and jointed structures called appendages. A. Jointed appendages: “joint foot”=arthropoda

nasim-howard
Télécharger la présentation

Chapter 30

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. Chapter 30 Arthropods

  2. I. Features of Arthropods • A typical arthropod is a segmented, coelomate invertebrate animal with bilateral symmetry, an exoskeleton, and jointed structures called appendages. • A. Jointed appendages: • “joint foot”=arthropoda • An appendage is any structure, such as a leg , an antenna, or mouthpart that grows out of the body of an animal. Section 28.1 Summary – pages 741 - 746

  3. What is an arthropod? • Joints also allow powerful movements of appendages, and enable an appendage to be used in many different ways. • Mouthparts have sucking, ripping or chewing parts Section 28.1 Summary – pages 741 - 746

  4. Origins of Arthropods Section 28.2 Summary – pages 747 - 755

  5. Origins of Arthropods • Arthropods most likely evolved from an ancestor of the annelids. • Oldest, best –preserved • multicellular animal fossils • 600 million years old • Most numerous early arthropod: trilobites • -became extinct about 250 million years ago • Lived in the sea • Segmented bodies • Jointed appendages • First animals with eyes capable of forming images. • First terrestrial arthropods: scorpions Section 28.2 Summary – pages 747 - 755

  6. The total number of arthropods • Exceeds that of all other kinds of animals • combined . • 5,000,000 species • More species of beetles than vertebrates. • Size varies from 80 micrometers (parasitic mite)- to 3.6 m (giant crab found in the sea near Japan.) Section 28.2 Summary – pages 747 - 755

  7. Two main groups • Arthropods with jaws • 1.-Uniramia – (subphylum) insects • chilopoda and diplopoda • 2. Crustacea- (subphylum) shrimp, crab lobster • Arthropods with fangs and pincers • 1. Chelicerata (subphylum) – scorpions, mites, • spiders • ***Each subphyla represents a distinct evolutionary line.

  8. Arthropod Body Plan Segmentation in arthropods • In most groups of arthropods, segments have become fused into three body sections—head, thorax (mid body region), and abdomen. • Individual body segments often exist only in larval stages. (ex: catepillar) Section 28.1 Summary – pages 741 - 746

  9. Segmentation in arthropods • In other groups, even these segments may be fused. • Some arthropods have a head and a fused thorax and abdomen. Section 28.1 Summary – pages 741 - 746

  10. Segmentation in arthropods • In other groups, there is an abdomen and a fused head and thorax called a cephalothorax. • Fusion of the body segments is related to movement and protection. Section 28.1 Summary – pages 741 - 746

  11. Arthropods have acute senses • A compound eye is a visual structure with many lenses. • See motion much more quickly than humans. Section 28.1 Summary – pages 741 - 746

  12. Accurate vision is also important to the active lives of arthropods. • Most arthropods have one pair of large compound eyes and three to eight simple eyes. • A simple eye is a visual structure with only one lens that is used for detecting light. • In dragonflies and locusts, these simple eyes function as horizon detectors. –helps them stabilize their position in flight. Section 28.1 Summary – pages 741 - 746

  13. Arthropod exoskeletons provide protection • The exoskeleton is a hard, thick, outer covering made of protein and chitin (KI tun). • Brittle and can break easily Section 28.1 Summary – pages 741 - 746

  14. Arthropod exoskeletons provide protection • In some species, the exoskeleton is a continuous covering over most of the body. • In other species, the exoskeleton is made of separate plates held together by hinges. • Crustaceans : thick relatively inflexible exoskeleton. • Insects and arachnids: soft and flexible exoskeleton. Section 28.1 Summary – pages 741 - 746

  15. Arthropod exoskeletons provide protection • The exoskeleton protects and supports internal tissues and provides places for attachment of muscles. • In many aquatic species, the exoskeletons are reinforced with calcium carbonate. Section 28.1 Summary – pages 741 - 746

  16. Why arthropods must molt • Exoskeletons have their disadvantages. • First, they are relatively heavy structures. The larger an arthropod is, the thicker and heavier its exoskeleton must be to support its larger muscles. Section 28.1 Summary – pages 741 - 746

  17. Why arthropods must molt • A second and more important disadvantage is that exoskeletons cannot grow, so they must be shed periodically. Shedding the old exoskeleton is called molting. Section 28.1 Summary – pages 741 - 746

  18. Why arthropods must molt • When the new exoskeleton is ready, the animal contracts muscles and takes in air or water. • This causes the animal’s body to swell until the old exoskeleton splits open, usually along the back. Section 28.1 Summary – pages 741 - 746

  19. Why arthropods must molt • Before the new exoskeleton hardens, the animal puffs up as a result of increased blood circulation to all parts of its body. • Thus, the new exoskeleton hardens in a larger size, allowing some room for the animal to continue to grow. Section 28.1 Summary – pages 741 - 746

  20. Why arthropods must molt • Most arthropods molt four to seven times in their lives before they become adults. • When the new exoskeleton is soft, arthropods cannot protect themselves from danger because they move by bracing muscles against the rigid exoskeleton. Section 28.1 Summary – pages 741 - 746

  21. Respiration: Arthropods have efficient gas exchange • Arthropods have efficient respiratory structures that ensure rapid oxygen delivery to cells. • This large oxygen demand is needed to sustain the high levels of metabolism required for rapid movements. Section 28.1 Summary – pages 741 - 746

  22. Arthropods have efficient gas exchange • Three types of respiratory structures have evolved in arthropods: gills, tracheal tubes, and book lungs. Section 28.1 Summary – pages 741 - 746

  23. Arthropods have efficient gas exchange • Aquatic arthropods exchange gases through gills, which extract oxygen from water and release carbon dioxide into the water. Section 28.1 Summary – pages 741 - 746

  24. Arthropods have efficient gas exchange • Land arthropods have either a system of tracheal tubes or book lungs. Section 28.1 Summary – pages 741 - 746

  25. Arthropods have efficient gas exchange • Most insects have tracheal tubes, branching networks of hollow air passages that carry air throughout the body. Section 28.1 Summary – pages 741 - 746

  26. Arthropods have efficient gas exchange • Muscle activity helps pump the air through the tracheal tubes. • Air enters and leaves the tracheal tubes through openings on the thorax and abdomen called spiracles. Section 28.1 Summary – pages 741 - 746

  27. Arthropods have efficient gas exchange • Most spiders and their relatives have book lungs, air-filled chambers that contain leaflike plates. Section 28.1 Summary – pages 741 - 746

  28. Arthropods have efficient gas exchange • The stacked plates of a book lung are arranged like pages of a book. Section 28.1 Summary – pages 741 - 746

  29. Excretion: • Most terrestrial arthropods excrete wastes through Malpighian tubules. • Slender, fingerlike extensions from the arthropods gut that are bathed in blood. • In insects, the tubules are all located in the abdomen rather than in each segment. • Malpighian tubules are attached to and empty into the intestine. • Metabolic wastes remain in the gut and leave the body through the anus. Section 28.1 Summary – pages 741 - 746

  30. II. Spiders and other Arachnids Section 28.2 Summary – pages 747 - 755

  31. What is an arachnid? • Spiders, scorpions, mites, and ticks belong to the class Arachnida (uh RAK nud uh). • Spiders are the largest group of arachnids. • Spiders and other arachnids have only two body regions—the cephalothorax and the abdomen. • They have no antennae • Arachnids have six pairs of jointed appendages. Section 28.2 Summary – pages 747 - 755

  32. What is an arachnid? • The first pair of appendages, called chelicerae,islocated near the mouth. Section 28.2 Summary – pages 747 - 755 chelicerae

  33. What is an arachnid? • Chelicerae are often modified into pincers or fangs. • Pincers are used to hold food, and fangs inject prey with poison. Section 28.2 Summary – pages 747 - 755

  34. What is an arachnid? • Spiders have no mandibles for chewing. • Using a process of extracellular digestion, digestive enzymes from the spider’s mouth liquefy the internal organs of the captured prey. The spider then sucks up the liquefied food. Section 28.2 Summary – pages 747 - 755

  35. What is an arachnid? • The second pair of appendages, called the pedipalps, are adapted for handling food and for sensing. pedipalps • Sometimes the pedipelps are for reproduction. • Following the pedipalps, are 4 pairs of appendages called walking legs. Section 28.2 Summary – pages 747 - 755

  36. What is an arachnid? • Although all spiders spin silk, not all make webs. • Spider silk is secreted by silk glands in the abdomen. Section 28.2 Summary – pages 747 - 755

  37. What is an arachnid? • As silk is secreted, it is spun into thread by structures called spinnerets, located at the rear of the spider. Section 28.2 Summary – pages 747 - 755

  38. A Spider Legs Simple eyes Cocoon Silk glands Book Lungs Pedipalps Chelicerae • Spiders are predatory animals, feeding almost exclusively on other arthropods.(=carnivores) Section 28.2 Summary – pages 747 - 755

  39. Ticks, mites, and scorpions: Spider relatives • Ticks and mites differ from spiders in that they have only one body section. Section 28.2 Summary – pages 747 - 755 tick

  40. Ticks, mites, and scorpions: Spider relatives • The head, thorax, and abdomen are completely fused. • Plant mites- while feeding may pass viral and fungal infections to plants. • Dust mites- live in carpet, bedding, clothing. (cause allergies) • Chiggers-known for their irritating bite Section 28.2 Summary – pages 747 - 755 • Ticks feed on blood from reptiles, birds, and mammals.

  41. Ticks, mites, and scorpions: Spider relatives • Mites feed on fungi, plants, and animals. • They are so small that they often are not visible to the unaided human eye. • Like ticks, mites can transmit diseases. • Lyme disease is spread by deer ticks Section 28.2 Summary – pages 747 - 755

  42. Ticks, mites, and scorpions: Spider relatives • Scorpions are easily recognized by their many abdominal body segments and enlarged pincers.(=pedipalps) • They have a long tail with a venomous stinger at the tip. Which is used to stun their prey. Section 28.2 Summary – pages 747 - 755

  43. Insects • Flies, grasshoppers, lice, butterflies, bees, and beetles are just a few members of the class Insecta. • Insects have three body segments (head thorax and abdomen) and six legs. • Head- mandibles (chewing mouth part) pair of antennae, compound eyes • Thorax - (composed of 3 fused segments.) • 3 pair of jointed walking legs and some have wings that are attached to the thorax. • Abdomen- is composed of 9-11 segments Section 28.2 Summary – pages 747 - 755

  44. Arthropods have other complex body systems • The mandibles, together with other mouthparts are adapted for holding, chewing, sucking, or biting the various foods eaten by arthropods. Section 28.1 Summary – pages 741 - 746

  45. A Grasshopper Antennae Legs Eyes Wings Spiracles Section 28.2 Summary – pages 747 - 755 Malpighian tubules Tympanum Nervous System

  46. Insect reproduction/Life Cycle • Insects usually mate once during their lifetime. • The eggs usually are fertilized internally. • Some insects exhibit parthenogenesis, reproducing from unfertilized eggs. Section 28.2 Summary – pages 747 - 755

  47. Insect reproduction • Most insects lay a large number of eggs, which increase the chances that some offspring will survive long enough to reproduce. Section 28.2 Summary – pages 747 - 755

  48. Metamorphosis: Change in body shape and form • After eggs are laid, the insect embryo develops and the eggs hatch. • In some wingless insects development is direct; the eggs hatch into miniature forms that look just like tiny adults. Section 28.2 Summary – pages 747 - 755

More Related