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What’s an Animal

Explore the characteristics and classification of two major animal groups - Porifera (sponges) and Cnidaria (stinging celled animals) - including their evolution, anatomy, reproduction, and examples.

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What’s an Animal

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  1. What’s an Animal • Multicellular • Eukaryotic • Heterotroph • Cells Lack cell walls

  2. Major Kinds • 2 Major Divisions • Invertebrates • Vertebrates

  3. Trends In Animal Evolution Bilateral Symmetry Radial Symmetry Posterior end Dorsal side Anterior end Ventral side Plane ofsymmetry Planes ofsymmetry

  4. Porifera Hole Bearing Animals The Sponges

  5. Porifera • First Sponges 580 Million years ago • Among the most ancient animals • Most Marine • Once thought to be plants • Adult sponges are sessile (do not move - attached) • No Symmetry

  6. Microciona sp.

  7. Ciona sp.

  8. Tube Sponges - Bonaire

  9. Vase Sponge - Bonaire

  10. Porifera • Sponges are multicellular, heterotrophic, have no cell wall, and contain specialized cell types that live together • No mouth, gut, tissues, organs • That is why sponges are thought to have evolved separately from other animals

  11. Porifera • Form and Function in Sponges • body forms a wall around a central cavity • lots of holes • Current of water goes through cells from collar cells • Many have spicules that form the skeleton of the sponge • Amebocyte – forms spicules – CaCO3 or SiO2 • Softer, stronger are sponge skeletons made of spongin • Some both

  12. Porifera • Water flowing through sponge acts as respiratory, excretory, and internal transport system • A sponge 10 cm high, 1 cm in diameter pumps about 22 liters of water a day through its body

  13. Reproduction • Water carries sperm away – collar cells of another sponge pick them up and amebocytes carry the sperm to the egg for fertilization • Asexually too • Gemmules – spheres of amebocytes surrounded by spicules may form – can survive long periods of cold or drying

  14. Classes • 3 Classes: • Calcispongiae – calcium carbonate spicules • Hyalospongiae – siliceous (glass spicules) • 6 rayed spicules, collar cells limited to certain chambers • Demospongiae – siliceous spicules, spongin, or both

  15. Osculum Pore Cell Porocyte Spicules Collar Cell Choanocyte Amebocyte Epidermal Cell

  16. Cnidaria The Stinging Celled Animals

  17. Characteristics • Soft bodied • Stinging cells • All aquatic • Radial symmetry • Exoskeleton of lime or chitin in some (corals) • No excretory or respiratory systems • Polyp (sessile) and or Medusa (bell shaped) “Jellyfish” stages

  18. Characteristics • Considered carnivores • Lack centralized nervous system

  19. Characteristics • Internal space – gastrovascular cavity • - digestion takes place in this cavity • Body wall – 3 layers • internal – gastroderm • middle – mesoglea • outer - epidermis

  20. Reproduction • Asexual or Sexual • Budding • Many Cnidarians have polyps that bud medusa that release gametes that form a ciliated larva that swims around for a while then settles down and grows into a polyp

  21. Jellyfish Life Cycle Section 26-3 Female medusa(2N) MEIOSIS Fertilization occurs in the open water, producing many diploid zygotes. Egg (N) FERTILIZATION Adult medusas reproduce sexually by releasing gametes intothe water. Sperm (N) Each zygote grows into a ciliated larva. The larva eventually attaches to a hard surface and develops into a polyp. Zygote (2N) Male medusa(2N) Youngmedusa Swimming larva Polyp The polypbuds to release young medusas. Buddingpolyp Haploid Diploid

  22. Figure 26–12 The Polyp and Medusa Stages Tentacles Mesoglea Gastrovascular cavity Mouth/anus Mouth/anus Gastrovascularcavity Tentacles Section 26-3 Epidermis Mesoglea Gastroderm Medusa Polyp

  23. Nematocysts • Cells with barbed dart coiled inside with a sac of poison • Tentacles have concentration of nematocysts • Tentacles push food into the mouth • Into the gastrovascular cavity

  24. Nematocysts

  25. Class Hydrozoa • Dominant, obvious stage is the polyp • usually have short medusa stage • Example: Hydra, Obelia, Hydractinia

  26. Class Hydrozoa

  27. Hydractinia echinata Snail Fur

  28. Tubellaria

  29. Millepora sp.

  30. Class Scyphozoa • True Jellyfish • Dominant, obvious stage is Medusa • usually have short polyp stage • Example: Lion’s Mane, Sea Nettle, Moon Jelly

  31. Cyeana capillata Lion’s Mane Jellyfish

  32. Class Cubozoa • “Cube” Shaped • Alternation of Generations • Unusually strong swimmers • a meter in five to ten seconds • Well Developed eyes

  33. Chironex fleckeri • about the size of a human head • has tentacles up to three meters long • A big sting from this guy can easily kill a human, with death occurring in as little as three minutes • among the deadliest creatures in the world

  34. Carybdea alata • About 1.5 to 3 inches in diameter and about 10 inches in length • Single tentacle on each corner of the bell • Most of day in deep water, night come toward surface to feed • Extremely painful to fatal

  35. Carybdea alata

  36. Carybdea alata

  37. Carybdea alata

  38. Chironex fleckeri

  39. Class Anthozoa • No Medusa Stage • Always polyp • Example: Coral, Anemone

  40. Telia Anemone

  41. Metridium senile Frilled Anemone

  42. Astrangia danae Star Coral

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