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biodiversity of animals invertebrates


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biodiversity of animals invertebrates

  1. 1. UNIT 4: BIODIVERSITY OF ANIMALS: INVERTEBRATES ( Campbell and Reece, 2010: Chapter 32 and 33)
  2. 2. Welcome to Your Kingdom • The animal kingdom extends far beyond humans and other animals we may encounter • 1.3 million living species of animals have been identified • Invertebrates (animals that lack a backbone) account for 95% of known animal species.
  3. 3. EARLY EMBRYONIC DEVELOPMENT IN ANIMALS  Most animals reproduce sexually, with the diploid stage usually dominating the life cycle  After a sperm fertilizes an egg, the zygote undergoes rapid cell division called cleavage  Cleavage leads to formation of a blastula  The blastula undergoes gastrulation, forming a gastrula with different layers of embryonic tissues.
  4. 4. Fig. 32-2-1 EARLY EMBRYONIC DEVELOPMENT IN ANIMALS Cleavage Zygote Eight-cell stage
  5. 5. Fig. 32-2-1 32-2-2 EARLY EMBRYONIC DEVELOPMENT IN ANIMALS Blastula Cleavage Cleavage Cleavage Eight-cell stage ygote Zygote Eight-cell stage Blastocoel Cross section of blastula
  6. 6. Fig. 32-2-1 32-2-2 Fig. 32-2-3 EARLY EMBRYONIC DEVELOPMENT IN ANIMALS Blastula Blastocoel Cleavage Cleavage Cleavage Cleavage Cleavage Endoderm Ectoderm Blastula Eight-cell stage Archenteron Zygote ygote Eight-cell stage Zygote Eight-cell stage Gastrula Blastocoel Blastocoel Blastopore Cross section of Cross section blastula of blastula Gastrulation
  7. 7. • Many animals have at least one larval stage. • A larva is sexually immature and morphologically distinct from the adult; it eventually undergoes metamorphosis.
  8. 8. 2. RELATIONSHIP BETWEEN BODY PLAN AND GROUPING OF ANIMALS IN PHYLA • Zoologists sometimes categorize animals according to a body plan. • A body plan is a set of morphological and developmental traits, integrated into a functional whole living animal.
  9. 9. CHARACTERISTICS WHICH EXPLAIN BODY PLAN • • • • • Symmetry Cephalization Tissues) Body cavities Protostome and Deuterostome development
  10. 10. A. SYMMETRY • Animals can be categorized according to the symmetry of their bodies, or lack of it • Some animals have radial symmetry • Two-sided symmetry is called bilateral symmetry
  12. 12. Bilaterally symmetrical animals have: – A dorsal (top) side and a ventral (bottom) side – A right and left side – Anterior (head) and posterior (tail) ends
  13. 13. B. CEPHALIZATION • Cephalization, the development of a head
  14. 14. C. TISSUES • Animal body plans also vary according to the organization of the animal’s tissues • Tissues are collections of specialized cells • During development, three germ layers give rise to the tissues and organs of the animal embryo
  15. 15. GERM LAYERS ARE: • Ectoderm is the germ layer covering the embryo’s surface • Endoderm is the innermost germ layer and lines the developing digestive tube, called the archenteron • Mesoderm: middle layer of some body plans
  16. 16. • Diploblastic animals have ectoderm and endoderm • Triploblastic animals have an ectoderm, endoderm and intervening mesoderm layer.
  17. 17. D. BODY CAVITIES • Most triploblastic animals possess a body cavity • A true body cavity is called a coelom and is derived from mesoderm • Coelomates are animals that possess a true coelom • A pseudocoelom is a body cavity derived from the mesoderm and endoderm • Triploblastic animals that possess a pseudocoelom are called pseudocoelomates • Triploblastic animals that lack a body cavity are called acoelomates
  18. 18. E. PROTOSTOME AND DEUTEROSTOME DEVELOPMENT • Based on early development, many animals can be categorized as having protostome development or deuterostome development • These two types of developments differ in regard to: • Different cleavage • Different coelom formation • Fate of the blastopore
  19. 19. CLEAVAGE • In protostome development, cleavage is spiral and determinate • In deuterostome development, cleavage is radial and indeterminate • With indeterminate cleavage, each cell in the early stages of cleavage retains the capacity to develop into a complete embryo
  20. 20. COELOM FORMATION • In protostome development, the splitting of solid masses of mesoderm forms the coelom. • In deuterostome development, the mesoderm buds from the wall of the archenteron to form the coelom.
  21. 21. FATE OF THE BLASTOPORE • The blastopore forms during gastrulation and connects the archenteron to the exterior of the gastrula • In protostome development, the blastopore becomes the mouth • In deuterostome development, the blastopore becomes the anus
  22. 22. 3. SYNOPTIC CLASSIFICATION OF THE ANIMAL KINGDOM Kingdom: Animalia Branch 1: Mesozoa (fish parasites) Branch 2: Parazoa (cellular) Phylum: Porifera (sponges) Branch 3: Eumetazoa (multicellular)
  23. 23. Branch 3: Eumetazoa (multicellular) • Grade 1: Radiata (Radial symmetry, tissue level) Phylum: Cnidaria hydras corals sea-anemones • Grade 2: Bilateria (Bilateral symmetry, organ level, cephalisation)
  24. 24. Grade 2: Bilateria (Bilateral symmetry, organ level, cephalisation) • Division 1: Protostomia • Division 2: Deuterostomia
  25. 25. Division 1: Protostomia • Group 1: Acoelomata (no body cavity) Phylum: Platyhelminthes (flat worms) • Group 2: Pseudocoelomata (pseudo body cavity) Phylum: Nematoda (round worms) • Group 3: Eucoelomata Phylum: Annelida (earthworms, leeches: Metamerism) Phylum: Arthropoda (crabs, insects: Tagmatisation) Phylum: Mollusca (slugs, snails)
  26. 26. Division 2: Deuterostomia Phylum: Echinodermata sea stars seaurchins Phylum: Chordata (vertebrates)
  27. 27. SUMMARY OF PHYLA • • • • • • • • Phylum: Phylum: Phylum: Phylum: Phylum: Phylum: Phylum: Phylum: urchins) • Phylum: Porifera (sponges) Cnidaria (Hydra, sea anemones) Platyhelminthes (flat worms) Nematoda (round worms) Annelida (earthworms, leeches) Arthropoda (crabs, insects) Mollusca (slugs, snails) Echinodermata (sea stars, sea Chordata (vertebrates)
  28. 28. Phylum: Porifera (sponges) • Sedentary animals (fixed in one position) • They live in both fresh and marine waters • Cellular level of development • Lack true tissues and organs • Asymmetrical
  29. 29. Phylum:Cnidaria (Hydra, sea anemones) • True tissue – Eumetazoa • Both sessile and motile forms including jellies, corals, and hydras • Diploblastic body plan • Radial symmetry • The basic body plan of a cnidarian is a sac with a central digestive compartment, the gastrovascular cavity • A single opening functions as mouth and anus
  30. 30. • Carnivores that use tentacles to capture prey • The tentacles are armed with cnidocytes, unique cells that function in defense and capture of prey • Nematocysts are specialized organelles within cnidocytes that eject a stinging thread.
  31. 31. Phylum: Platyhelminthes (flat worms) • Live in marine, freshwater, and damp terrestrial habitats. • Triploblastic development • Acoelomates • Flattened dorsoventrally and have a gastrovascular cavity • Gas exchange takes place across the surface • Protonephridia regulate the osmotic balance
  32. 32. Phylum: Nematoda (round worms) • Found in most aquatic habitats, in the soil, in moist tissues of plants, and in body fluids and tissues of animals • They have an alimentary canal, but lack a circulatory system • Sexual Reproduction • Internal fertilization • Some species are parasites of plants and animals.
  33. 33. Phylum: Annelida (earthworms, leeches) • Bodies composed of a series of fused rings or compartments - Metamerism
  34. 34. Phylum: Arthropoda (crabs, insects) • Found in nearly all habitats of the biosphere  The arthropod body plan consists of a  segmented body,  hard exoskeleton (made of layers of protein and the polysaccharide chitin  jointed appendages • The body is completely covered by the cuticle • When it grows, it molts its exoskeleton. • Includes: insects, crabs, spiders, millipedes, centipedes, mites…
  36. 36. Phylum: Mollusca (slugs, snails) • Includes snails and slugs, oysters and clams, and octopuses and squids • Most are marine, some inhabit fresh water and some are terrestrial • Soft bodied animals, but most are protected by a hard shell.
  37. 37. Phylum: Echinodermata (sea stars, sea urchins) • Shared characteristics define deuterostomes (Chordates and Echinoderms) – Radial cleavage – Formation of the mouth at the end of the embryo opposite the blastopore • Echinoderms have a unique water vascular system, a network of hydraulic canals branching into tube feet that function in locomotion, feeding, and gas exchange
  38. 38. Phylum: Echinodermata
  39. 39. Phylum: Chordata (vertebrates) • Phylum Chordata consists of two subphyla of invertebrates as well as hagfishes and vertebrates • Vertebrates are a subphylum within the phylum Chordata • Chordates are bilaterian animals that belong to the Deuterostomia. • All chordates share a set of derived characters • Some species have some of these traits only during embryonic development
  40. 40. Four key characteristics of chordates – Notochord – Dorsal, hollow nerve cord – Pharyngeal slits or clefts – Muscular, post-anal tail