1. “Spiny Skinned Animals”
Echinoderms
“Spiny Skinned Animals”

2. Spiny skinned because of the calcium carbonate internal skeleton

3. Echinoderm Characteristics
Radial Symmetry (aboral and oral sides)
All marine
Most pentamerous
No heart, gills, lungs, brain, or eyes
Nutrients and gases transported in fluid that fills body cavity
Water vascular system
Calcium carbonate internal skeleton
Nervous system is simple nerve net

4. Sides of the Echinoderm
Oral Side:
mouth
ampullae- store water
ambulacral groove
tube-feet
Aboral Side:
pedicellariae-pinchers
anus
Madreporite-water opening

5. Oral Side
Ampullae
Tube Feet

6. Aboral Side
Pedicellariae
(all over surface)

7. Pedicellariae: tiny pinchers amongst the spines to help keep off parasites & catch bits of food

8. Water Vascular System (WVS)
Hydraulic system containing Tube Feet, attached to appullae which store water for the WVS.
Used for:
locomotion
attachment
sensation
feeding
gas exchange

9. Water Vascular System Ring Canal Madreporite Radial Canal
With Ampullae

10. Water Vascular System

11. Water Vascular System Tube Feet

12. Tube feet and ampulla

13. Feeding Some carnivorous (sea stars)
Some detritus foragers ( urchins & sea cucumbers)
Some planktonic feeders (feather stars and basket stars)
Many have mouth on oral surface and anus on aboral surface. Sea stars can extend stomach out of mouth and engulf and digest prey
Sea cucumbers can eviscerate gut

14. Sea Star feeding on clam

16. Reproduction The sexes are separate in most
Many release sperm and egg into water
Most form pelagic bilaterally symmetrical larvae
Asexual reproduction and Regeneration

17. Sexual Reproduction Fertilization produces pelagic planktonic larvae
Sea Star Larvae
Brittle Star Larvae
Sea Urchin Larvae

18. Asexual Reproduction by regeneration-all you need is one arm & part of the central disk!

19. Echinoderms : Five Classes
Feather Stars, sea Lillies (Crinoidea)
Sea Stars (Astroidea)
Brittle Stars, Basket Stars (Ophiuroidea)
Sea Urchins, heart urchins, sand dollars (Echinoidea)
Sea Cucumbers (Holothuroidea)

20. Feather Stars and Sea Lilies (Crinoidea)
600 species
Crinoids
Most ancient class
Mouth open up instead of down
5 arms radiate from pentagon shaped body- arms branch into 10 or more arms
Tube feet used for filter feeding
Sea lilies found in deeper water

21. Golden Chrinoid CR-269/355 found on coral reefs

22. Feather Star CR-269/355 here the arms are closed (rolled up)
notice the claw-like appendages attaching it to rock

23. Sea Stars (Asteroidea)
1500 living species
Usually 5 rays radiating from central disk
Many are active carnivores
Excessive numbers can harm marine ecosystems
Ability to regenerate entire body from one arm and portion of central disk

24. West Indian Sea Stars Juvenile and Adult CR-271 / 367 Shallow sea grass beds and sandy flats

25. West Indian Cushion Star in a Turtle Grass bed

26. West Indian Cushion Star Four Rays Only

27. Cushion star Oral view

28. West Indian Cushion Star Six Rays

29. Seven Ray Cushion Star

30. Common Comet Stars CR-275/361 found on reef notice the different numbers of rays- why the name Comet?

31. Two-Spined Sea Star Oral View CR-277/363 Notice the ambulacral groove on reach ray

32. Two-Spined Sea Star Aboral View most often found on sandy bottoms in shallow waters- often burrow into sand

33. Thorny Sea Stars CR-277/365 found on rock rubble and mangrove roots (same genus as Orange-ridged sea star)

34. Thorny Sea Star often found hiding under rocks

36. Brittle Stars, Basket Stars, Serpent Stars (Ophiuroidea)
Brittle stars are most numerous (2000 species)!!!
Most active echinoderm with swift snake-like movements
Under rocks during day & feed on detritus at night
Usually 5 thin, flexible arms radiate from central disk
Basket stars have complex branched arms used to catch plankton

37. Blunt Spined Brittle Star CR-283/373

38. Blunt-Spined Brittle Star
CR-283

39. Red Brittle Star

40. Banded-Arm Brittle Star CR-285/375

41. Sponge Brittle Star (CR 281/371)

42. Sponge Brittle Star on zoanthid CR-281/371

43. Ruby Brittle Star CR-283/373

44. Giant Basket Star (closed) CR-287/377

45. Giant Basket Star (open) open mostly at night filtering planktonic animals

46. Sea Urchins, Heart Urchins, and Sand Dollars (Echinoidea)
“without arms”
Test: Calcareous plates fused into shell
Often covered with spines- spines often used for locomotion instead of tube feet
Most hide during day and are more active at night
Sand dollars and heart urchins burrow under the sand during day
Most feed on detritus or algae

47. Diadema Long Spined Sea Urchin CR-287/379

48. Rock Boring sea Urchin CR-289/380 Aboral View - shorter spines- shallow rocky tidal area

49. Rock Boring Sea Urchin Oral View

50. Diadema Rock Boring

51. Slate Pencil Sea Urchin CR= 291/385 found on sea grass beds and reef ruble

52. West Indian Sea Egg CR-293/385 found in sea grass beds and shallow reefs

53. West Indian Sea Egg oral view

54. Variegated Urchin CR-291/383

55. Red Heart Urchin CR-293/387 hide under sand during day – when discovered, will “jump” out

56. Six-Keyhole Sand Dollar CR-295/389 covered with short spine “fuzz”

57. Sea Cucumbers (Holothuroidea)
Elongated soft body – no spines
Bilateral symmetry
Skeletal plates are very small and buried under leathery body wall
Some have tentacle-like tube feet around mouth
Mouth in front and anus at rear
Defense mechanisms

58. Three Rowed Sea Cucumber (CR-297/392)

59. Agassiz Sea Cucumber

60. Florida Sea Cucumber CR-397 found in shallow sand flats and sea grass beds

61. Donkey Dung Sea Cucumber CR-297/395 inhabit sandy areas around reefs and sea grass beds

62. Behavior Sea Cucumber Expelling CuvierianThreads Defense Mechanism
(actually Part of the animal’s gut
These threads are toxic
And can be quickly
Regenerated.
Behavior

63. Sea Cucumber Poop

64. Pearlfish and Sea Cucumbers have an INTERESTING RELATIONSHIP