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this ppt about class astroidea in phylum echinodermata and on soft skeleton and what preserve in it and its paleogeography in egypt and its benefits in geology

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  2. 2. AGENDA • CLASSIFICATION • General characteristics • SKELETON • Morphology of soft parts • Symmetry • Mode of life & Environment • Reproduction • Respiration • Feeding • Paleobiogeography 10/19/2016 2
  3. 3. Classification 10/19/2016 3 Kingdom : Animalia Subkingdom : Metazoa Phylum : Echinodermata Class ASROIDEA
  4. 4. General characteristics of Astoidea • Usually sedentary along shorelines • Starfish or sea stars • Come in a variety of colors • Prey on bivalve mollusks such as clams & oysters • Have 5 arms that can be regenerated • Arms project from the central disk • Mouth on oral surface (underside) 10/19/2016 4
  5. 5. EXAMPLE (STAR FISH ) • Starfish or sea stars are star- shaped echinoderms belonging to the class Asteroidea. Common usage frequently finds these names being also applied to ophiuroids, which are correctly referred to as brittle stars or "basket stars". About 1,500 species of starfish occur on the seabed in all the world's oceans, from the tropics to frigid polar waters. They are found from the intertidal zone down to abyssal depths, 6,000 m (20,000 ft) below the surface. • 10/19/2016 5
  6. 6. TYPES OF STAR FISH 10/19/2016 6 • Most starfish have five arms that radiate from a central disc, but the number varies with the group. • Luidia ciliaris has seven arms, members of the Solasteridae have ten to fifteen while the Antarctic Labidiasternnulatus can have up to fifty. It is not unusual in species that typically have five arms for some individuals to possess six or more through abnormal development. •
  7. 7. SKELETON 10/19/2016 7
  8. 8. Water vascular system • Water vascular system: hydraulic system for locomotion, food & waste transportation, & respiration. • • Water vascular system: consists of set of waterfilled canals branching from ring canal ( encircles gut). The canals lead to tube feet, (sucker-like appendages). Madreporite is entrance of this system 10/19/2016 8
  9. 9. Skeleton (body wall) & grade of organization • Skeleton- below dermis • made of ossicles (CaCO3) • lattice like connections • Calcium carbonate • with spines and tubercles • Muscle layer- below dermis • Peritoneum that lines coelom 10/19/2016 9 • Epidermis- outer surface; includes • mucous cells • epithelium • Pedicellariae- jawlike appendages of the epidermis • can open and close • used to clean body of debris or put debris on body • Dermis- includes • nerve cells • connective tissue
  10. 10. Symmetry • Pecta radial symmetry 10/19/2016 10
  11. 11. Mode of life & Environment • Mode Of life • Environment Marine water 10/19/2016 11
  12. 12. Reproduction • Most species of starfish are gonochorous, there being separate male and female individuals • Some species are simultaneous hermaphrodites, producing eggs and sperm at the same time and in a few of these • Each starfish arm contains two gonads that release gametes through openings called gonoducts, located on the central disc between the arms. • Fertilization is generally external but in a few species, internal fertilization takes place 10/19/2016 12
  13. 13. Reproduction summary • dioecious; external fertilization • usually 10 gonads; 2 in each arm • have fissiparity- division of central disc into two animals • free living larvae • bipinnaria- first larval form develops into • brachiolaria - shows development of arms 10/19/2016 13
  14. 14. Respiration • Starfish rely on osmosis, in order to gather oxygen from the surrounding water The hole on the top of their bodies is called madreporite. • Water is gathered through the madreporite and fills a cavity in the center of the starfish's body called the coelom. • The coelom is intersected by a number of body canals that run from the center of the starfish to the tips of each arm. • These canals fill with the water from the coelom. • The tube feet that are connected to these canals also fill with water. • Carbon dioxide then flows through the thin skin of the starfish's tube feet and body into the surrounding water while oxygen travels through the skin membrane and into the starfish's body. 10/19/2016 14
  15. 15. Feeding and its mechanism • Tube feet attach to bivalve mollusk shells & create suction to pull valves apart slightly • Starfish everts (turns inside out) its stomach through its mouth & inserts it into prey • Stomach secretes enzymes to partially digest bivalve then stomach withdrawn & digestion completed inside starfish • Starfish are powerful hunters and primarily feed on mollusks. Their main sources of food are clams, oysters sand dollars and mussels 10/19/2016 15
  16. 16. Evolutionary history • Echinoderms first appeared in the fossil record in the Cambrian • The first known asterozoans were the Somasteroidea, which exhibit characteristics of both groups • Starfish are infrequently found as fossils, possibly because their hard skeletal components separate as the animal decays • However, although starfish fossils are uncommon, there are a few places where accumulations of complete skeletal structures occur, fossilized in place in Lagerstätten — so-called "starfish beds 10/19/2016 16
  17. 17. Paleobiogeography 10/19/2016 17
  18. 18. References • Lawrence, J. M., ed. (2013). Starfish: Biology and Ecology of the Asteroidea. Johns Hopkins University Press. . • Ruppert, Edward E.; Fox, Richard, S.; Barnes, Robert D. (2004). Invertebrate Zoology, 7th edition. Cengage Learning. • Byrne, M.; O'Hara, T. D.; Lawrence, J. M. "Asterias amurensis". Starfish: Biology and Ecology of the Asteroidea. pp. 177–179. in Lawrence (2013) 10/19/2016 18

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  • SohelSr1

    Apr. 5, 2018

this ppt about class astroidea in phylum echinodermata and on soft skeleton and what preserve in it and its paleogeography in egypt and its benefits in geology


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