1. Phylum
    2. 1. Classification of Animals
    2. Protozoa
    3. Porifera
    4. Coelenterata
    5. Platyhelminthes
    6. Nemathelminthes
    7. Annelida
    8. Earthworm
    9. Arthropoda
    10. Cockroach
    11. Mosquito
    12. Honey bee and Silk moth
    13. Mollusca
    14. Echinodermata
    15. Hemichordata
    16. Chordata
    17. Pisces
    18. Amphibia
    19. Frog
    20. Reptile
    21. Aves
    22. Mammalia
    23. Rabbit bone
  2. Animal Behaviour and Adaptation
    3. 24. Animal behaviour
    25. Animal adaptation
    26. Migration
  3. Developmental Biology
    4. 27. Development of Animals
    28. Development of Frog
  4. Human Biology
    5. 29. Tissues
    30. Sense organs
    31. Digestive system
    32. Circulatory system
    33. Respiratory system
    34. Nervous system
    35. Endocrine system
    36. Reproductive system
    37. Excretory system
    38. Skeletal system
    39. Basic concept of Immunology
    40. Human diseases
  5. Evolutionary Biology
    6. 41. Origin of Life
    42. Organic Evolution
    43. Theories of Evolution
    44. Evolution of Human beings
    45. Horse Evolution
Phylum
14. Echinodermata
▢ General Features:
❖ BodyStructure:
  1. Triploblastic
  2. Radially symmetrical (adult), often Pentamerous
  3. Larva is bilaterally symmetrical; sessile or creeping at bottom
  4. Radially arranged parts are called Antimeres
  5. Tube within tube body plan (Deuterostomes)
  6. Digestive tract complete (except in Brittle star)
  7. Enterocoelic coelomate
  8. Organ grade of organization
  9. Unsegmented body
▢ Habit: Gregarious
▢ Habitat:
❖ Type: Exclusively marine
❖ Lifestyle:
  1. All are benthic (bottom dwellers), except few pelagic sea cucumbers
  2. Mostly free-living, except sea lilies
▢ Special Features:
❖ BodySurface:
  1. Spiny skinned
  2. Uncephalized (head absent)
  3. Body parts organized around oral-aboral axis
❖ Endoskeleton:
◉ Structure: Unique calcareous ossicles bearing protective spines
◉ Origin: Mesodermal
◉ Significance: Only phylum other than Chordata with true endoskeleton
❖ ExternalStructures:
  1. Spines – pointed for protection
  2. Pedicellariae – pincer-like, prevent setting of foreign particles
❖ SpecialOrgans: In Sea urchin, gut has a masticating organ called 'Aristotle’s Lantern'
❖ CoelomicSystems:
◉ Description: Complex coelom with derivatives: Water vascular system, Perivisceral coelom, Haemal system
◉ WaterVascularSystem:
◈ Pathway:
  1. Madreporite (Inlet canal)
  2. Stone canal (Madreporic canal)
  3. Ring canal (lined with Tiedmann's bodies for lymphocyte formation)
  4. Radial canal
  5. Lateral canal
  6. Tube feet (Ampulla, Podium, Sucker)
◈ Functions:
  1. Locomotion
  2. Respiration
  3. Food capturing
❖ DefenseAndRegeneration:
  1. Autotomy – breaking part to confuse enemy
  2. Evisceration – ejection of viscera
  3. Regeneration – by epimorphosis
❖ BodyWall: Contains muriform glands in epidermis for pigmentation
▢ Nervous System:
❖ Type: Diffuse and decentralized
❖ Components:
  1. Nerve net
  2. Nerve ring
  3. Radial nerves
❖ Note: No brain present
❖ SenseOrgans:
  1. Tactile tentacles
  2. Pigment eye-spots
  3. Statocysts (organs of balance/orientation with statoliths)
▢ Respiratory System:
❖ Organs:
    ◈ Animal: Starfish
    ◈ Organ: Dermal branchiae or Papulae
    ◈ Animal: Sea urchin
    ◈ Organ: Gills
    ◈ Animal: Sea cucumber
    ◈ Organ: Cloacal Respiratory Tree
    ◈ Animal: Brittle star
    ◈ Organ: Genital bursae
▢ Circulatory System:
❖ Type: Open
❖ Heart: Absent
❖ Blood: No respiratory pigment
▢ Excretory System: Absent
▢ Reproductive System:
❖ Type: Mostly dioecious
❖ Copulation: Absent
❖ Fertilization: External
❖ Eggs: Homolecithal (uniform yolk distribution)
❖ Development:
◉ Type: Indirect via free-swimming larvae
◉ Cleavage: Radial and indeterminate
◉ LarvalForms:
◈ Asteroidea (Starfish - Asteriasis):
  1. Bipinnaria
  2. Brachiolaria
  3. Dipleura
◈ Ophiuroidea (Brittle star - Ophiothrix):
  1. Ophiopluteus
◈ Echinoidea (Sea urchin - Echinus):
  1. Echinopluteus
◈ Holothuroidea (Sea cucumber - Cucumeria):
  1. Auricularia
◈ Crinoidea (Feather star - Antedon):
  1. Doliolaria
◉ Note: Dipleura is the common ancestral larval form of most deuterostomes
▢ Classification:
❖ Based on the shape/position of madreporite and characteristics of the digestive system:
S.N.
Asteroidea
Ophiuroidea
Echinoidea
Holothuroidea
Crinoidea
Body Form
  1. Star-like with 5 arms not demarcated from central axis
  2. • Starfish is benthonic (bottom dwelling), carnivorous animal.
  3. • Starfish is nocturnal and eats its prey.
  4. • Starfish is an enemy of Pearl oyster.
  5. • The stomach comes out of the body, feeds and digests food outside the body (i.e., extra oral digestion occurs in starfish).
  6. • Facts: The Sea Star (Starfish)
  1. Snake tail-like
  2. • Star-like with 5 arms demarcated from central axis.
  3. • Ambulacral grooves are absent in its living forms.
  4. • Facts: The Basket Star
  1. Spiny
  2. • Globular with no arms.
  3. • Skeleton bearing movable spines and three-jawed pedicellariae are present.
  4. • Facts: The Sea Urchin
  5. • It contains Sphaeridia.
  6. b. Echinocardium (Heart urchin)
  7. c. Clypeaster (Dollar star/Sand dollar)
  8. • Box-like calcareous test is found in Sand dollar.
  9. • Facts: The Sand Dollar
  1. Cucumber-like
  2. • No arms, no spines, no pedicellariae.
  3. • Madreporite is absent.
  4. • Feeds upon detritus and planktons.
  5. • Facts: The Sea Cucumber
  1. Lily flower-like
  2. • Arms bear pinnules.
  3. • Tube feet without suckers, no madreporite, spines and pedicellariae.
  4. • No madreporite
Madreporite location
Aboral
Oral
Aboral
Oral
No madreporite
Pedicellariae
Pedicellariae are present
Anus and pedicellariae are absent
Movable spines and three-jawed pedicellariae are present
No pedicellariae
No pedicellariae
Examples
  1. a. Asterias (Starfish)
  2. b. Astropecten (Starfish)
  3. c. Pentaceros (Sea pentagon)
  1. a. Ophiothrix (Brittle star)
  2. b. Gorgonocephalus (Basket star)
  1. a. Echinus (Sea urchin)
  2. b. Echinocardium (Heart urchin)
  3. c. Clypeaster (Dollar star/sand dollar)
  1. a. Cucumaria (Sea cucumber)
  1. a. Antedon (Feather-star / Sea lily)
  2. b. Holopus (Sea-lilies)
  3. c. Neometra (Feather star)
1. Which of the following animal belongs to Echinodermata?

[IOM 2003]

  • Sea urchin (Echinus)
  • Sea horse
  • Sea hare
  • Sea mouse
2. Locomotory organ in starfish is:

[IOM 2002]

  • Tentacles
  • Feet
  • Water vascular system
  • Cilia
3. Well developed water vascular system is found in:

[IOM 1997]

  • Mollusca
  • Echinodermata
  • Porifera
  • Pisces
4. Which phylum is exclusively marine

[MOE 2003]

  • Porifera
  • Coelenterata
  • Mollusca
  • Echinodermata
5. Organisms attached to substratum generally possess

[IE 2008]

  • Asymmetrical body
  • Radial symmetry
  • Cilia on surface to create water current
  • One single opening of digestive canal
6. In which of following classes of echinodermata bipinnaria larvae is found

[IE 2004]

  • Asteroidea
  • Crinoidea
  • Pentameria
  • Ophiuroidea
7. Which of the following is an echinodermata?

[IOM 2014]

  • Sepia
  • Devil fish
  • Sea urchin
  • Hydra
8. Echinodermata lives in
  • Fresh water
  • Ground water
  • Marine water
  • Rain water