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Comparing Invertebrates

Comparing Invertebrates. Chapter 29. Invertebrate Evolution. Chapter 29-1. Origins of Invertebrates. Early animals were flat, soft bodied organisms that lived on the bottom of shallow seas. Segmented with bilateral symmetry. NO cell specialization.

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Comparing Invertebrates

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  1. Comparing Invertebrates Chapter 29

  2. Invertebrate Evolution Chapter 29-1

  3. Origins of Invertebrates Early animals were flat, soft bodied organisms that lived on the bottom of shallow seas. Segmented with bilateral symmetry. NO cell specialization. Recently scientists discovered microscopic fossils that are 610-570 million years old. Seem to be developing embryos of early multi-cellular organisms. 29-1 Invertebrate Evolution

  4. 29-1 Invertebrate Evolution The First Multicellular Animals • Ediacaran Fossils found in China • 610 to 570 Million Years old • They are the ancestors of today’s multicellular animals

  5. 29-1 Invertebrate Evolution The First Multicellular Animals • The fossils: • were flat and plate shaped • were segmented • had bilateral symmetry • lived on the bottom of shallow seas • were made of soft tissues • absorbed nutrients from the surrounding water

  6. 29-1 Invertebrate Evolution Invertebrate Phylogeny • Many features of modern invertebrates evolved during the Cambrian period such as: • tissues and organs • patterns of early development • body symmetry • cephalization • segmentation • formation of three germ layers and a coelom

  7. 29-1 Invertebrate Evolution Invertebrate Phylogeny • Invertebrate Evolutionary Relationships

  8. 29-1 Invertebrate Evolution Invertebrate Phylogeny Roundworms Flatworms Cnidarians Sponges Unicellular ancestor

  9. 29-1 Invertebrate Evolution Invertebrate Phylogeny

  10. 29-1 Invertebrate Evolution Invertebrate Phylogeny

  11. 29-1 Invertebrate Evolution Invertebrate Phylogeny • Invertebrate Evolutionary Relationships

  12. Evolutionary Trends Specialized cells, Tissues, and Organs Sponges - 1st with specialized cells Jelly fish - 1st with muscle tissue Flatworms - 1st with organs Body Symmetry Asymmetrical (no symmetry) – Sponges only Radial – Jellyfish and Echinoderms Bilateral – Flatworms, Roundworms, Annelids, arthropods, and Mollusks 29-1 Invertebrate Evolution

  13. 29-1 Invertebrate Evolution Evolutionary Trends • Cnidarians and echinoderms exhibit radial symmetry where parts extend from the center of the body. Radial symmetry Planes of symmetry

  14. 29-1 Invertebrate Evolution Evolutionary Trends • Worms, mollusks, and arthropods exhibit bilateral symmetry, or have mirror-image left and right sides. Bilateral symmetry

  15. Cephalization Cephalization is the concentration of sense organs and nerve cells in the front of the body. Invertebrates with cephalization can respond to the environment in more sophisticated ways than can simpler invertebrates. None: Sponges Nerve Net: Cnidarians Ganglia: Worms, Clams, Echinoderms Brains: Cephalopod Mollusks, Arthropods 29-1 Invertebrate Evolution Evolutionary Trends

  16. 29-1 Invertebrate Evolution Evolutionary Trends • Segmentation • Over the course of evolution, different segments in invertebrates have often become specialized for specific functions. • Segmentation allows an animal to increase its size with minimal new genetic material.

  17. 29-1 Invertebrate Evolution Evolutionary Trends • Coelom Formation • Flatworms are acoelomates. This means they have no coelom, or body cavity, that forms between the germ layers. Endoderm Ectoderm Mesoderm Digestive cavity Acoelomate

  18. 29-1 Invertebrate Evolution Evolutionary Trends • Pseudocoelomates have a body cavity lined partially with mesoderm. Pseudocoelom Digestive tract Pseudocoelomate

  19. 29-1 Invertebrate Evolution Evolutionary Trends • Most complex animal phyla have a true coelom that is lined completely with tissue derived from mesoderm. Coelom Digestive tract Coelomate

  20. 29-1 Invertebrate Evolution Evolutionary Trends

  21. 29-1 Invertebrate Evolution Evolutionary Trends • Embryological Development  • In most invertebrates, the zygote divides to form a blastula—a hollow ball of cells.

  22. 29-1 Invertebrate Evolution Evolutionary Trends • In most worms and arthropods, nerve cells are arranged in structures called ganglia. • In more complex invertebrates, nerve cells form an organ called a brain.

  23. 29-1 Invertebrate Evolution Evolutionary Trends

  24. 29-1 Invertebrate Evolution Evolutionary Trends

  25. Invertebrate Form & Function Chapter 29-2

  26. The End

  27. Feeding and Digestion Intracellular: Food digested by cells and passed around by diffusion. (ex: sea anemone) 29-2 Form and Function in Invertebrates • Extracellular: food • broken down in • cavity and then • absorbed. (ex: earthworm)

  28. 29-2 Form and Function in Invertebrates Feeding and Digestion • Feeding and Digestion • The simplest animals break down food primarily through intracellular digestion. More complex animals use extracellular digestion.

  29. 29-2 Form and Function in Invertebrates Feeding and Digestion • When food is digested inside cells, this process is known as intracellular digestion. • Sponges use intracellular digestion.

  30. 29-2 Form and Function in Invertebrates Feeding and Digestion • In extracellular digestion, food is broken down outside the cells in a digestive cavity or tract and then absorbed into the body. • Mollusks, annelids, arthropods, and echinoderms rely almost entirely on extracellular digestion. • Flatworms and cnidarians use both intracellular and extracellular digestion.

  31. 29-2 Form and Function in Invertebrates Feeding and Digestion • Cnidarians and most flatworms ingest food and expel wastes through a single opening. • Food is digested in a cavity through both extracellular and intracellular means.

  32. 29-2 Form and Function in Invertebrates Feeding and Digestion Mouth/anus Gastrovascular cavity Digestive cavity Cnidarian Pharynx Mouth/anus Flatworm

  33. 29-2 Form and Function in Invertebrates Feeding and Digestion • In more-complex animals, food enters the mouth and wastes leave through the anus. • A one-way digestive tract often has specialized regions.

  34. 29-2 Form and Function in Invertebrates Feeding and Digestion Intestine Gizzard Crop Pharynx Mouth Annelid Anus Crop Pharynx Anus Arthropod Mouth Stomach and digestive glands Rectum Intestine

  35. 29-2 Form and Function in Invertebrates Respiration • All respiratory systems have two basic requirements: • a large surface area that is in contact with the air or water • the respiratory surfaces must be moist for diffusion to occur

  36. Aquatic invertebrates: Require moist respiratory surfaces Some through the pores of the skin Some through gills (large feathery structure rich in blood vessels) 29-2 Form and Function in Invertebrates Respiration

  37. 29-2 Form and Function in Invertebrates Respiration • Aquatic Invertebrates • Gills are feathery structures that expose a large surface area to the water.

  38. 29-2 Form and Function in Invertebrates Respiration Book Lungs Spiracles • Terrestrial Invertebrates: • Covered by water or mucus inside the body. • Book lungs – spiders • Spiracles - other insects

  39. 29-2 Form and Function in Invertebrates Respiration • Terrestrial Invertebrates • Grasshoppers and other insects have spiracles and tracheal tubes.

  40. 29-2 Form and Function in Invertebrates Circulation • Most complex animals have one or more hearts to move blood through their bodies and either an open or closed circulatory system

  41. Open – blood partially contained in vessels Closed – blood forced through vessels 29-2 Form and Function in Invertebrates Circulation

  42. 29-2 Form and Function in Invertebrates Circulation • Open Circulatory Systems • In an open circulatory system, blood is only partially contained within a system of blood vessels. • One or more hearts or heartlike organs pump blood through blood vessels into a system of sinuses, or spongy cavities. • The blood makes its way back to the heart.

  43. 29-2 Form and Function in Invertebrates Circulation • Open circulatory systems are characteristic of arthropods and most mollusks.

  44. 29-2 Form and Function in Invertebrates Circulation • Closed Circulatory Systems • In a closed circulatory system, a heart or heartlike organ forces blood through vessels that extend throughout the body. • Materials reach body tissues by diffusing across the walls of the blood vessels. • Closed circulatory systems are characteristic of larger, more active animals.

  45. 29-2 Form and Function in Invertebrates Circulation • Among the invertebrates, closed circulatory systems are found in annelids and some mollusks. Heartlike structure Small vessels in tissue Blood vessels Annelid: Closed Circulatory System Heartlike structures

  46. 29-2 Form and Function in Invertebrates Excretion • Most animals have an excretory system that rids the body of metabolic wastes while controlling the amount of water in the tissues. • In aquatic invertebrates, ammonia diffuses from their body tissues into the surrounding water.

  47. Aquatic invertebrates: Diffusion: aquatic mollusks, sponges, and jelly fish Mollusk examples Flame cells: flatworms 29-2 Form and Function in Invertebrates Excretion

  48. 29-2 Form and Function in Invertebrates Excretion • Terrestrial Invertebrates • Convert ammonia to urea to conserve water • Nephridia: Terrestrial mollusks and earthworms • Malpighian tubules: insects and spiders

  49. 29-2 Form and Function in Invertebrates Excretion Flame Cells • Flatworms use a network of flame cells to eliminate excess water. Excretory tubules Flame Cell Excretory tubule Flatworm

  50. 29-2 Form and Function in Invertebrates Excretion • In annelids and mollusks, urine forms in tubelike structures called nephridia. Nephrostome Excretory pore Annelid Nephridia

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