Question

Write the general charaters of echinodermata mention the characters of class echinoidea and holothuroidea with examples

Answer 1

Characters of echinodermata are -
(i) They are marie water organisms
(II) they have tissue level organization
(III) they have radial symmetry
(iv) they are heterotropic
(v) they have tube feet for locomotion
(vi) reproduction is sexual

Answer 2

Heya!!!

General characters of Echinodermata:

➡They are non chordate deuterostomes and enterocoelomates...

➡All are marine...

➡The adult Echinoderms are Radially symmetrical (Pentamerous radial symmetry) , larvae are bilaterally symmetrical...

➡ Body wall is thick and body surface is spiny...

➡Echinoderms possess a mesodermal endoskeleton of Calcareous ossicles, which support the spines , hence the name Echinodermata was assigned...

➡The most distinctive feature of Echinoderms is Presence of Water vascular system or ambulacral system derived from the coelom which helps in locomotion , capture and transport of food and respiration...

➡ Circulatory system is open type without heart and blood vessels.....

➡ Respiratory organs are Papulae pr dermal branchiae , Cloacal respiratory trees etc...

➡Special excretory organs are absent.... Excretion is by simple diffusion...

➡ Nervous system is poorly developed....Brain is absent....sense organs are poorly developed...

➡Sexes are separate but no sexual dimorphism...

➡ Fertilization is usually external...

➡ Development is indirect with a free-swimming bilaterally symmetrical larva...

➡Power of regeneration is remarkable...

Examples :Asterias ,Echinus etc...




Characters of class Echinoids :

➡It includes sea urchins, heart urchins ,sand dollars etc...

➡The body is ovoid , discoid and covered by movable spines ...

➡Arms are absent...

➡ Calcareous ossicles of the body unite to form a rigid test or corona or case ...

➡Pedicellariae are three jawed...

➡Ambulacral grooves are closed...

➡A complex five jawed masticatory apparatus called Aristotle's Latern is present Just inside the mouth .It is absent in heart urchins...

➡Life history includes larval form Called Echinopluteus...

➡Specialised gills called peristomial gills occur in sea urchins.

Examples : Echinus (Sea urchin), Echino cardium (Heart Urchin)..



Characters of Holothuroidea :

➡ This class includes sea cucumbers...

➡ Body is elongated in oro-aboral axis...

➡Arms,spines and pedicellariae are absent...

➡Skin is leathery and dermis contains loose spicules ...

➡ Mouth is surrounded by retractile feeding tentacles...

➡Madroporite is internal,amburacral grooves are closed ...

➡Tube feet bear s_u_c_k_e_r_s..

➡ Respiratory organs are a pair of Cloacal respiratory trees...

➡ Development is indirect and includes Auricularia larva...

Examples:Synapta , Thyone..


Hope this helps you :)


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