1. Phylum Echinodermata

2. MCDOUGALL VIDEO CH. 13 – ECOLOGY AND ORGANIZATION OF BOGS

3. MCDOUGALL VIDEO CH 14 PREDATOR PREY 1 - ENEMONE

4. Porifera
Platyhelmithes
Mollusca
Arthropoda
Echinodermata
Hemichordata
Cnidaria
Nemertea
Annelida
Lophophores
Chordata
Protozoans

5. Common Body Plan Adults are pentaradially symmetrical
5 sets of body parts around an oral-aboral axis 5

6. Common Body Plan However, larvae are bilaterally symmetrical
Settle near adults of their species and attach to substrate
Metamorphosis: left side becomes oral surface of the adult and right side becomes aboral (not oral)
Larval mouth/anus disappear, gut migrates to adult position, and new mouth/anus open 6

7. Endoskeleton
Unique system of calcareous plates (ossicles) – calcium carbonate
Reduced in sea cucumbers
Fused in sea urchins/sand dollars 7

8. Endoskeleton
Skeletal elements bear pincer-like structures called pedicellariae
Use to rid body of debris, defense, grasp objects to hide, or capture/hold prey 8

9. Water-vascular system
Hydraulic system of canals and reservoirs controls the movement of tube feet (podia)
Critical to locomotion, gas exchange (respiration), feeding, and sensory reception 9

10. Water-vascular system
Water enters sieve plate (madreporite)
Flows from stone canal to radial canals in each arm
Lateral canals perpendicular to the radial canal terminate in muscular bulb (ampulla) connected to a tube foot 10

11. Water-vascular system
Water enters bulb, it contracts and water forced into foot
Extends foot, pressing terminal sucker onto substrate
Foot contracts, forcing water back into bulb and raises center of sucker
Creates a vacuum seal; only broken when bulb contracts water into foot again 11

12. Members of the Phylum Echinodermata
Date back 570 million years ago
13,000 fossil species
Only 7,000 species today
Most are marine and benthic (90%)
Range in size (<1cm to 2 m)
5 Classes 12

13. Phylum Echinodermata Radial symmetry No head or brain Spiny skin
Water vascular system
No excretory organs
Deuterostome
Bilateral lavrae

14. Class Asteroidea 1500 species of sea stars
5 or more broad arms surround a central disk
Crawl on rocks or live on sea bottom
Most are scavengers or predators
Each arm bears podia with suckers
Evert stomach into prey and digest it 14

15. Class Asteroidea Star Fish
5 or more tapering arms
Mouth on underside
Endoskeleton
Ossicles
Tube feet
Feed on molluscs and sea urchins

16. Fig. 22.2a

17. Fig. 22.2b

18. Pedicellaria
Spine
Pedicellaria
Dermal
branchia

19. Class Asteroidea Tube feet and ambulacral groove Aboral surface

20. Aboral Surface
Madreporite

21. Water vascular system Madreporite Stone canal Ring canal Tiedemann’s
bodies
Radial canal
Lateral canal
Tube feet
Polian
vesicles

22. Tube feet

23. Tube foot Ampulla Lateral canal Body wall Tube foot Retractor muscles
Podial muscle
Sucker

24. Movement of tube feet

25. Body Wall and Internal Anatomy of a Sea Star
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Body Wall and Internal Anatomy of a Sea Star 25

26. Fig. 22.3a

27. Feeding

28. Class Ophiuroidea Brittle Stars and Basket Stars
Central disc with distinct arms
No pedicellariae
Tube feet lack suckers and ampulla

29. Class Ophiuroidea 2000 species of brittle stars
Usually concealed in sand or under objects
Some live in sponges or other colonial organisms
Only 5 arms that are usually highly branched 29

30. Class Ophiuroidea Arms are distinct from central disk Can crawl/cling
Predators, scavengers, or suspension feeders
Flexible arms bear suckerless podia that secrete mucus to entrap food and transport it to mouth 30

31. Brittle star
Mouth
Bursal slit

32. Basket Star

33. Class Echinoidea Sea Urchins
Shell (test) encloses body
Ossicles form plates
No arms
Long spines
Movement
Venom

34. Class Echinoidea 1000 species of sea urchins/sand dollars
Movable spines and podia surround body; used for locomotion
Herbivorous, detrivorous, suspension feed, a few predators 34

35. Class Echinoidea Unique feeding apparatus called Aristotle’s lantern
Hard plates and muscles just inside mouth
Possesses 5 calcareous teeth
Teeth protract to scrape algae off rocks or tear chunks of kelp 35

36. Internal Anatomy of a Sea Urchin
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Internal Anatomy of a Sea Urchin

37. Class Echinoidea Sand Dollar
Burrow in sand

38. Sand dollar
Gonopore
Madreporite
Ambulacral region
Lunule

39. Class Holothuroidea Sea Cucumbers
Soft body with reduced ossicles
Tentacles near mouth
Respiratory tree
Breaths through anus

40. Class Holothuroidea 1150 species of sea cucumbers
Mucus-covered oral tentacles trap on plankton or ingest sand organic matter
Gut modified to produce respiratory trees used for gas exchange
Expel portions of these trees as defense mechanism; regenerate 40

41. Fig. 22.Fig. 22a

42. Class Cridoidea Feather Stars and Sea Lilies
Most primitive
Feather like arms used for suspension feeding
Plankton
Tube feet trap planktonic organism
Cilia in ambulacral grooves carry food to mouth

43. Attach to substrate with stalk Sessile sea lily
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Class Crinoidea: Sea Lily
Attach to substrate with stalk
Sessile sea lily
Cup-like body attached to stalk
Attached to substrate
Can bend stalk and flex/extend arms

44. Class Crinoidea: Feather Star
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Class Crinoidea: Feather Star
Swim and crawl

45. Class Crinoidea Free-moving feather star
Stalk lost during larval development
Can crawl/swim
Jointed appendages (cirri) help it regain balance 45

46. Central disk
Mouth
Anus
Pinnule

47. Ancestral Echinoderms

48. Ancestral Echinoderms