Phylum Echinodermata: Notes, Examples & NEET MCQs (Class 11 Biology)

 

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Table of content 

1. ​Introduction to Phylum Echinodermata
2. ​General Characteristics of Echinodermata 
3. Water Vascular System in Echinodermata
4. ​Classification & Important Classes
5. ​Detailed Study: Antedon (Sea Lily)
6. ​Examples of Echinodermata 
7. ​NEET Important Point Table
8. ​Practice MCQs for NEET 2025

Introduction to Phylum Echinodermata

• Phylum Echinodermata includes exclusively marine animals that are found at all depths of the ocean.
• The name "Echinodermata" comes from Greek: Echinos = spiny + derma= skin, referring to their spiny body surface.
• They are believed to have evolved about 500 million years ago and are closely related to chordates.
• Echinoderms  are  marine  animals with spiny bodies with calcareous ossicles.
• This is  Phylum which have close  relationship with chordates .
• No any member of Echinoderms is fresh water. They are the closest invertebrates to Chordates.

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General Characteristics of Echinodermata 

• They have endoskeleton of calcareous ossicle and look spiny therefore they called as Echinoderms.
• They are exclusively marine. 
• They are Coelomate, Triploblastic with organ system level of organisation .
• The  adults Echinoderms are radial symmetrical but larva possess bilateral symmetry.

Video Lecture Highlights 

00:00 - Introduction to Phylum Echinodermata
01:15 - Habitat and Marine Nature
02:13 - Symmetry Twist (Larva vs Adult) [NEET IMP]
03:45 - Level of Organization & Germ Layers
05:30 - Digestive System & Mouth Position
06:03 - Water Vascular System (Ambulacral System)
07:42 - Why Excretory System is Absent?
11:42 - Hand-drawn Diagram of Starfish
12:33 - Functions of Tube Feet (Podia)
13:34 - Conclusion & Notes Info

• Digestive system is complete. Mouth is located on ventral side and anus is present on dorsal side.
• Water vascular system or Ambulacral system is most distinctive feature of Echinoderms.
• Water vascular system is involved in Respiration, transportation of food and capturing of prey.
• Excretory system is absent in Echinoderms.
• Sexes are separated. They reproduce only sexually. Fertilisation is usually external.
• Development is indirect with free swimming larva.

Water Vascular System in Echinodermata

• The water vascular system is a unique hydraulic system of coelomic origin found only in echinoderms.
• It helps in locomotion, food capture, respiration, and excretion through tube feet.
• Water enters through a porous plate called the madreporite located on the aboral surface.

💡​​Path of water in water vascular system 

 ​Madreporite ➡️ Stone canal ➡️ Ring canal ➡️ 5 Radial canals ➡️ Lateral canals ➡️ Tube feet.

• The evolutionary significance of water vascular system is that it shows their relationship with chordates.

💡 Related study to understand the Phylum Porifera : Phylum Porifera (Sponges) NCERT Notes & MCQs for NEET Biology

Examples of Echinodermata

Ophiura

• It is also known as Brittle star.
• Body is divided into oral and aboral surface.
• Central disk and arms are quite distinct.
• It has considerable change in spine armature and color pattern.
• Aboral surface has radial shield in Central disk.
• Mouth in oral surface has complicated system of  plates spine tube feet.
• At the base of each arm, bursal slits are present.
• Central disk has endoskeleton of calcium carbonate and present also in internal organs.

Ophiura

 Cucumaria

• It is also known as sea cucumber.
• Oral end contains whorl of 10 dendrite and pinnately branches tentacles around the mouth. Tentacles are modified tube feet.
• Anterior end contains collar which contain mouth.
• Rest  of body  is divided into five Ambulacral groove and five inter Ambulacral groove.
• Aboral surface has radial shield in Central disk.
• Mouth in oral surface has complicated system of  plates spine tube feet.
• Tube feet when present contain suckers.
• Body wall contain very  small seprate ossicle.
• Larval is Auricularia or Doliolaria.

Cucumaria

Echinus

• It is also known as sea urchin.
• Body is differentiated into flat oral and dome shaped aboral surface.
• Anterior end contains collar which contain mouth.
• Body is enclosed by globular test which contain calcareous plates.

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• Entire surface of body is covered by the movable articulated spines except peristome and periproct.
• Mouth in oral surface has complicated system of  plates spine tube feet.
• Pedicellariae and sphaeridia are defensive and offensive organ.
• Oral surface contain mouth from where jaw apparatus or Aristotle lantern are spread internally for mastication.

Echinus

Antedon

• It is also known as sea lily or feather star.
• On aboral surface,   calyx bear knob like structure called centro dorsal plates.
• Calyx is differentiated into oral surface that bear mouth and anus and aboral surface in which arms and cirri are inserted.

🔥 NEET Key Highlights (Must Remember!)

• Symmetry: Adults are Radial, but Larvae are Bilateral.
• Excretory System: Completely ABSENT. (Excretion by diffusion).
• Water Vascular System: Used for Locomotion, Food Capture, and Respiration.
• Endoskeleton: Made of Calcareous Ossicles.
• Fertilization: Usually External with indirect development.

• Aboral surface is covered by leathery skin in  which  calcareous plates are inserted.
• On aboral surface , calyx bear a knob like structure called as stung of stalk.
• Mouth is central and directly upward to lead into five Ambulacral groove.
• Water vascular system is well developed but madreporite are absent.
• There are ten arms which contain numerous pinnules containing gonads. 

Antedon

Asterias 

• It is also known as  star fish.
• Body is radial symmetrical, star shaped and pentagonal.
• Body or central disk can be identified that  Mouth is located on ventral side and anus is present on dorsal side.
• Central disk in continued up to five arms.
• Aboral surface contain conical spines over the surface and over the sub pentagonal madreporite plate.

• Pedicellariae are present on aboral surface.
• Water vascular system is well developed but madreporite are present.
• Terminal tube feet is photosensitive.

Comparison table of various class of Echinoderm 

Class Name	Common Name	Example (Scientific Name)	Special Feature
Asteroidea	Star Fish	Asterias	Arms present, Tube feet with suckers
Echinoidea	Sea Urchin	Echinus	Aristotle’s Lantern (Chewing organ)
Holothuroidea	Sea Cucumber	Cucumaria	Body elongated, Arms absent
Crinoidea	Sea Lily	Antedon	Plant-like appearance, No spines
Ophiuroidea	Brittle Star	Ophiura	Long slender arms, Anus absent

To understand   the  detail  information about the  Phylum : Hemichordata Notes, Examples & NEET MCQs (Class 11 Biology) read my next detailed guide: .

🎯 NEET MULTIPLE CHOICE QUESTIONS

🔥 100% CHALLENGE

"Questions yahi se aayega... taiyari jeet ki!"

1. Term Echinodermata has been given due to presence of 
A. Exoskeleton of chitin
B. Endoskeleton of calcareous shell
C. Exoskeleton of calcareous ossicles
D. Endoskeleton of calcareous ossicles

Answer : D  

2. Which of the following statement is correct for the Echinoderms.

A. Some of the animals are fresh water.

B. Both adult and their larva are radial symmetrical.
C. Most of the animals have spiny body.
D. They have organ level of organisation.

Answer: C  

3. In Echinoderms:

A. Digestive system is incomplete and mouth only is present on ventral surface of body.

B.Digestive system is incomplete and anus only is present on dorsal surface of body.

C. Digestive system is complete and mouth  is present on ventral surface and anus is present on dorsal surface.

D. Digestive system is complete and and mouth  is present on dorsal surface and anus is present on ventral surface.

Answer : C 

4. Most remarkable feature of Echinoderms is 

A. Water vascular system 

B. Canal system

C. Tracheal system

D.All of the above.

Answer: A  

5. Consider the following functions of water vascular system and select the correct code:

1. Excretion

2. Respiration 

3.Caturing of food 

4. Transportation of food

A. 1, 2 and 3

B. 2, 3 and 4

C. 1 ,3 and 4

D. 1 ,2 and 4

Answer : B 

6. In Echinoderms:

A. Both larva and adult are radial symmetrical.

B. Both larva and adult are Bilateral symmetrical.

C. Larva is bilateral symmetrical and adult ar is radial symmetrical

D. Adult is bilateral symmetrical and larva is radial symmetrical

Answer : C 

 

7. Which one the following is Excretory organ in Echinodermata.

A. Protonephridia 

B. Pro nephros kidney

C. Proboscis glands 

D. Excretory system is absent

Answer : D 

8. Which of the following pair  is incorrect for the Echinoderms.

A. Reproduction: sexual

B. Development : direct

C. Saxes : seprate

D. Fertilization: External

Answer : B 

9. In the Echinoderms, Development is 

A. Direct with free swimming larval stage 

B. Direct with sessile larval stage

C. Direct and  larval resemble with the adult.

D. Indirect with no larval stage

Answer: A   

10. Sea lily is 

A. Antedon       B. Asterias

C. Echinus         D. Ophiura

Answer : A 

11. Match the list

A. Asterias      1.Star. Fish 

B. Cucumaria 2.Brittle star

C. Ophiura      3. Sea urchin

D. Echinus      4. Sea                                                                 Cucumber 

     A      B       C      D

A.  1       2       3      4

B.  1       4       2      3

C.  4      3        2      1

D.  4      2        3      1

Answer : B 

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