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Porifera_classification.ppt
- 1. Phylum – Porifera The Sponges
- 4. Taxonomy • Kingdom – Animalia • Subkingdom – Parazoa (lacks tissues) • Phylum – Porifera (pores)
- 5. INTRODUCTION TO PORIFERA • unusual animals • originally thought they were plants • primarily marine, mostly in shallower waters • sessile and attached to substrate or objects- occasionally on other animals such as crabs; occuring singly or colonies • the most primitive metazoans and have neither true tissues or organs
- 6. Characteristics o Simplest of all animals o Contain specialized cells but no other organization level o Most are marine o Saltwater sponges are brightly colored o Freshwater sponges are small and dull green color o Size – 2 meters to 2 cm
- 7. Characteristics o Porifera means pore- bearing o Water enters through pores bringing in food and oxygen o Filter feeders on plankton o Osculum – large opening at the top where excess water leaves
- 8. Water Flow Through the Sponge WATER IN WATER OUT Osculum
- 9. Water Flow Through Sponge
- 10. Characteristics o Asymmetrical o Sessile as adults (attach to rocks) o Free-swimming larval stage called Dipleurula o Also reproduce by fragmentation (pieces break off & form a new sponge)
- 11. Sponge Body Structure o Inside body cavity of sponge is hollow o Called the Spongocoel o Have 2 cell layers: Outer epidermis Inner endoderm o Jelly-like material between cell layers called mesenchyme
- 12. Sponge Body Structure • Multicellular but with few cell types; tissue organisation very much restricted & lacking organs & coordibnation between cells • Body perforated by number of pores • Having canal system through which water current flows with food & oxygen • Characteristic flagellated cells called choanocytes, lines inner side of the body wall & related to watre circulation
- 14. Sponge Body Structure • Absence of body cavity or gut • Presence of elaborate skeletal system of either calcareous or siliceous spicules or protein (collagen, sometimes called spongin) fibers or combination of these • Exclusively filter feeder • Gas exchange by diffusion • Absence of nervous system
- 15. Sponge Cell Types • Pinacocytes- outer cells covering sponge; equivalent of epiderm • Choanocytes- – similar to choanoflagellates – collared cells with flagella - create water current and collect food matter • Amoebocytes- – amoeba-like cells – store, digest and transport food, excrete wastes, secrete skeleton – give rise to buds in asexual reproduction
- 17. Mesophyl (=Mesenchyma) • Beneath the pinacocytes - a gelatinous protein layer • it contains the skeletal material (ie. spongin and spicules) and amoebocytes
- 18. •Choanocytes line the gastrovascular cavity & capture food •Amebocytes digest & distribute food
- 19. Specialized Cells • Choanocytes (collar cells) line inside of body cavity (spongocoel) • Have flagella that spins to pull in water & food • Collar traps plankton (food) from water Collar
- 21. o Amebocytes: • Pick up food from choanocytes • Finish digestion • Move through the mesenchyme & take food to other cells Other Specialized Cells
- 23. Skeletal Structure of the Sponge • Skeleton made of network of protein fibers called Spongin • Spicules are hard spear or star- shaped structures • Spicules made of CaCO3 (limestone) or silica (glass)
- 24. Sponge Skeletons SPONGIN Silica Spicules Limestone Spicules
- 27. Types of Spicules 4 general types • Monaxon- needle-like or rod-like; straight or curved • Tetraxon- has 4 prongs • Triaxon or Hexaxon- 3 or 6 rayed • Polyaxon- multiple short rods radiating from a common center; burr shaped, star shaped or like a child's jack. – Some species have a mixture of types
- 28. Spongin Give phylum its common name • Some species have no spicules, but do have spongin • spongin is a type of hardened secreted protein • Some species have both spicules and spongin
- 29. Sponge Reproduction o Sponges can regenerate (regrow) lost body parts through mitotic cell division (asexual) o Sponges also reproduce asexually by budding
- 30. Sponge Reproduction o Sponges are hermaphrodites (produce both eggs & sperm) o Sponges reproduce Sexually by releasing eggs & sperm into the water from the Osculum o Cross-fertilize each other’s eggs Sponge releasing eggs & sperm
- 31. Sexual Reproduction in Sponges • gametes formed by amoebocytes • there are both hermaphroditic and dioecious species – most hermaphroditic species produce eggs and sperm at different times so they do not self fertilize • sperm is released into environment via osculum and is brought in by another sponge via ostia • fertilization takes place in parent sponge • zygote is expelled - it drops to bottom and begins to develop
- 35. Asexual Reproduction in Sponges • two types: • Budding- fragmentation of body wall, buds appear as outgrowth on sides of sponge • when they reach a certain size they drop off and settle to bottom to form a new sponge
- 36. Asexual Reproduction in Sponges • Gemmules- occurs only in freshwater sponges • gemmules are groups of food laden amoebocytes that deposit a hard covering of spicules around them • formation is triggered by environmental conditions such as decreased temperatures • they allow the sponge to pass the winter or periods of drought • after which the outer covering breaks open and a new sponge develops
- 37. Gemmules
- 39. Reproduction
- 40. Surviving Harsh Conditions o Gemmules are specialized buds made to survive harsh weather (hot or cold) o Contain food, amebocytes, and a protective covering of spicules o Released when a sponge dies o Resist dessication (drying out) o Become adult sponge conditions become favorable
- 43. Vase Sponges
- 44. Barrel Sponges
- 45. Ball Sponges
- 46. Rope Sponges
- 50. HIGHER CLASSIFICATION OF PORIFERA 4 classes of sponges 1.Class Calcarea 2.Class Hexactinellida 3.Class Demospongiae 4.Class Sclerospongiae (Ruppert & Barnes, 1994)
- 51. Class Calcarea • Entirely marine, shallow & coastal water species, restricted to the depth less than 100 meters & require substratum for attachment • Small sized sponges, about 10 cm in height • Cylindrical or vase-like shape
- 52. Class Calcarea • Osculum narrow and placed terminally, provided with oscular fringe
- 53. Class Calcarea • Sketeton represented by calcareous spicules composed of calcium carbonate • spicules are monaxons or tri or quadraxons • all three types of sponges exhibited – ex. Sycon, Leucandra and Grantia
- 54. Class Hexactinellida (glass sponges) • Large sized sponge, 10 – 30 cm in height • Basically marine living in deep sea (200m – 1000m) and may grow in firm & soft sediments • Usually cup, vas or urn (vas with foot) - like shape with well developed/ enclosed spongoceol(=atrium) opening to wide osculum Eupectella
- 55. Class Hexactinellida (glass sponges) • Skeleton of six-rayed (triaxon); spicules of Silica (SiO2) and sometime fused to form a lattice like skeleton • Choanocytes restricted to finger-like simple folded chambers
- 57. Class Hexactinellida (glass sponges) • Canal system may be either syconoid or leuconoid type
- 58. Class Hexactinellida (glass sponges) Eupectella Hyalonema Pheronema
- 59. Class Demospongiae • Largest class - 95% of sponges in this class • Mostly marine, some are fresh-water or brackish water forms; in sea existing from shallow water to great depths
- 60. • Brilliant colouration in most species, presence of pigment granules in amoebocytes • Skeleton either absent or silicious(spicules), fibrous(spicules replaced by organic collagenous fibres, or both sopngin fibres as well as silicious spicules) • Canal system leuconoid type only • Flagellated chamber small & rounded • Parenchymula larva in the life cycle of most Demospongiae Class Demospongiae
- 63. Class Sclerospongiae • Marine, exhibits cryptic habits & prefer caves