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Phylum Echinodermata “Spine skin” Marine (or estuarine) Water vascular system Pentaradial symmetry.

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Presentation on theme: "Phylum Echinodermata “Spine skin” Marine (or estuarine) Water vascular system Pentaradial symmetry."— Presentation transcript:

1 Phylum Echinodermata “Spine skin” Marine (or estuarine) Water vascular system Pentaradial symmetry

2 Echinodermata 6500 species living 13,000 from fossils Classes: Crinoidea, Stelleroidea, Echinoidea, Holothuroidea

3 Water vascular system Fluid-filled canals that lead to tube feet Sea star: madreporite, stone canal, ring canal, radial canal, ampulla, tube feet

4 Water vascular system Tiedemann’s body: Contains phagocytes; remove foreign matter such as bacteria from incoming seawater

5 Water vascular system Ambulacral ossicles support ampullae and tube feet Contraction of ampulla moves fluid to tube feet Muscles in tube feet for retracting HPhAGyDceLo

6 Water vascular system Cilia on inner surface of tube feet circulate water Gas exchange Fluid similar to seawater; contains coelomocytes, proteins, K ions

7 Class Crinoidea Lily-like Feather stars and sea lilies Oldest of living echinoderms

8 Class Crinoidea Feeding, repro structures at top of stalk Complete digestive system in calyx: mouth – intestine, anus ch?v=s1xfRc4SDsw

9 Class Crinoidea Arms have ambulacral groove with mucus- secreting glands adjacent. Food particles stick in mucus, flicked to the ambulacral groove, then mouth

10 Class Stelleroidea Armed echinoderms Brittle stars, sea stars

11 Brittle stars and basket stars ~ 2100 described Joints allow flexibility Tube feet present Sensitive to light – oral surface mj8ZYysrmxU

12 Brittle stars and basket stars Tube feet through small holes Digestive system mostly in disc – no anus Bursal slits for water exchange

13 Deposit feeders, suspension feeders, carnivores, scavengers Many are nocturnal Many live in associations Brittle stars and basket stars

14 Sea stars ~ 1600 species Arms not as distinct from disc as in brittle stars Move slowly with tube feet Tube feet move individually

15 Figure 20_06

16 Sea stars Digestion: lower cardiac stomach digests food Upper pyloric stomach for secreting enzymes and absorption

17 Pedicellariae: stalked or sessile

18 Figure 20_09

19 Concentricycloids – sea daisies Recently (1986) discovered echinoderms > 1000 m New Zealand, Bahamas –Tube feet arrangement different

20 Class Echinoidea: spine-like Sea urchins, sand dollars < 1000 species

21 Class Echinoidea: spine-like Ossicles form test Complex system of ossicles and muscles for grazing = Aristotle’s lantern

22 Spines attach to skeleton – ball and socket joint Toxins Ossicles flat and joined = inflexible

23 Class Echinoidea: spine-like Tube feet in 5 double rows of plate Pedicellariae – globular forms have toxin

24 Feeding and digestion: Aristotle’s lantern Teeth protruded to scrape algae or consume food Species w/o lantern usually detritivores

25 Mouth – esophagus – intestine – anus WVS m/watch?v=D3W4OCn HyCs

26 Class Holothuroidea: sea cucumbers ~ 1200 species

27 Ossicles microscopic Multiple shapes

28 Tube feet modified into tentacles around mouth Mostly deposit-feeders, few filter-feeders

29 Digestion system: elongated Mouth – esophagus – stomach – intestine – cloaca – anus WVS – madreporite in coelomic cavity = no outside connection

30 Respiratory tree: connects to cloaca – water supply Expulsion of internal organs

31 Echinoderm repro + development: Some are asexual Most are dioecious Multiple gonads, gametes into seawater = external fert

32 Distinctive ciliated larval form in each class Free-swimming, planktonic Metamorphosis into adult

33 Echinoderm NS No brain 3 nerve networks Ectoneural = ring around esophagus: receives sensory input

34 Echinoderm NS Hyponeural = circumoral nerve: motor function Entoneural = associated with aboral end, neurons from stalk down arms


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